Table 1. Critical group doses from liquid discharges in the vicinity of Magnox sites (µSv)
Site	2006	Main Pathway (2006) ^a	2007	Main Pathway (2007) ^a
Berkeley.	1.2	Consumption of seafood	34	External exposure
Bradwell.	3.7	Consumption of seafood	57	External exposure
Chapelcross.	17	External exposure plus consumption of seafood	11	External exposure plus consumption of seafood
Dungeness A.^b	11	External exposure plus consumption of seafood	8.9	External exposure plus consumption of seafood
Hinkley Point A.^b	27	External exposure plus consumption of seafood	33	External exposure
Hunterston A ^b	35	External exposure plus consumption of seafood	14	External exposure plus consumption of seafood
Oldbury.	1.2	Consumption of seafood	35	External exposure plus consumption of seafood
Sizewell A.^b	8.7	External exposure plus consumption of seafood	6.9	External exposure plus consumption of seafood
Trawsfynydd	14	Consumption of fish	16	External exposure plus consumption of fish
Wylfa	1.8	Consumption of seafood	11	External exposure plus consumption of seafood

Table 2. Critical group doses from aerial discharges in the vicinity of Magnox sites (µSv)
Site	2006	Main Pathway (2006)^a	2007	Main Pathway (2007)^a
Berkeley	21	Consumption of milk & vegetables (infants)	17	Consumption of milk & vegetables (infants)
Bradwell	7.2	Consumption of milk & vegetables (infants)	6.5	Consumption of milk & vegetables (infants)
Chapelcross	11	Consumption of milk & vegetables (infants)	11	Consumption of milk (infants)
Dungeness A^c	31	Consumption of milk (infants)	28	Consumption of milk (infants)
Hinkley Point A ^c	6.1	Consumption of milk & vegetables (infants)	3.7	Consumption of milk (infants)
Hunterston A ^c	30	Consumption of milk (infants)	31	Consumption of milk (infants)
Oldbury ^b	21	Consumption of milk & vegetables (infants)	17	Consumption of milk & vegetables (infants)
Sizewell A ^c	18	Consumption of milk & vegetables (infants)	22	Consumption of milk & vegetables (infants)
Trawsfynydd	3.8	Consumption of vegetables (adults)	4	Consumption of vegetables (adults)
Wylfa ^b	13	Consumption of milk (infants)	25	Consumption of milk (infants)

Table 3. Summary of direct radiation doses to the most exposed members of the public at Magnox sites (µSv)
Site	2006	2007
Berkeley	41	< 60 ^b
Bradwell	< 73 ^b	< 63 ^b
Chapelcross	< 1 ^b	< 1 ^b
Dungeness A ^a	620 ^c	280 ^c
Hinkley Point A	< 1.9 ^b	3.4
Hunterston A	< 57 ^b	< 81 ^b
Oldbury ^a	< 6 ^b	< 6.9 ^b
Sizewell A ^a	< 28 ^b	< 33 ^b
Trawsfynydd	< 25 ^b	16
Wylfa ^a	< 9.5 ^b	< 10 ^b

Table 4. Summary of critical group doses^a in the vicinity of Magnox sites (µSv)
Site	2006	Main Pathway (2006)	2007	Main Pathway (2007)
Berkeley	62	Direct radiation plus consumption of milk (infants)	77	Direct radiation plus consumption of milk (infants)
Bradwell	80	Direct radiation	69	Direct radiation
Chapelcross	17	External exposure plus consumption of fish	12	Consumption of milk (infants)
Dungeness A	650^c	Direct radiation	308	Direct radiation
Hinkley Point A ^b	27	External exposure plus consumption of fish	33	External exposure
Hunterston A ^b	87	Direct radiation plus consumption of milk (infants)	112	Direct radiation plus consumption of milk (infants)
Oldbury	27	Consumption of milk & vegetables (infants) plus direct radiation	35	External exposure plus consumption of seafood
Sizewell A ^b	46	Direct radiation plus consumption of milk (infants)	55	Direct radiation plus consumption of milk (infants)
Trawsfynydd	28	Direct radiation plus consumption of vegetables (adults)	20	Direct radiation plus consumption of vegetables (adults)
Wylfa	23	Consumption of milk (infants) plus direct radiation	35	Consumption of milk (infants) plus direct radiation

1.0 Introduction

During 2007, Magnox Electric Ltd, on behalf of the Nuclear Decommissioning Authority (NDA) operated the two generating Magnox nuclear power stations; Oldbury and Wylfa, two sites (Sizewell A and Dungeness A) that are in the post operational defuelling phase, one site, Chapelcross, that is defuelling and five sites (Berkeley, Bradwell, Hinkley Point A, Hunterston A and Trawsfynydd) that have defuelled. At the end of 2006 Berkeley Nuclear Licensed site, previously Berkeley Centre and Berkeley Power Station that were covered by a combined licence, was re-licensed to incorporate the defuelled station, the shielded facilities and other labs adjacent to the shielded facilities. The remainder of the site was de-licensed. Also at the end of 2006 Sizewell A and Dungeness A ceased generation which will have has a significant impact on future radioactive discharges. Magnox Electric Ltd also operated the hydro-electric power station at Maentwrog in Gwynedd (Wales). The identity and status of each site is given in Table 5 and their locations can be found on the NDA web site.

Table 5. Locations and status of Magnox Electric Ltd Sites in 2007(NDA)
Site	Status	Reactors		Date opened	Generation in 2007			Date Ceased Generation	Date defuelled
		Number	Pressure vessel		Capacity (MW)	Output (GWh)
		Number	Pressure vessel		Capacity (MW)	Gross	Supplied
England
Berkeley	Decommissioning	2	Steel	1962	-	-	-	1989	1992
Bradwell	Decommissioning	2	Steel	1962	-	-	-	2002	2005
Dungeness A	Defuelling	2	Steel	1965	-	-	-	2006	-
Hinkley Point A	Decommissioning	2	Steel	1965	-	-	-	1999	2004
Oldbury	Generating	2	Concrete	1967	434	648	618	-	-
Sizewell A	Defuelling	2	Steel	1966	-	-	-	2006	-
Wales
Maentwrog	Generating	Hydro-electric		1928	28	58	58	-	-
Trawsfynydd	Decommissioning	2	Steel	1965	-	-	-	1993	1995
Wylfa	Generating	2	Concrete	1971	980	5684	4769	-	-
Scotland
Chapelcross	Defuelling	4	Steel	1959	-	-	-	2004	-
Hunterston A	Decommissioning	2	Steel	1964	-	-	-	1990	1995

1.1 Environmental reporting by Magnox Electric Ltd

This report summarises the comprehensive data that are available for inspection by members of the public on the Public Registers maintained by the Environment Agency (EA) in England and Wales and Scottish Environment Protection Agency (SEPA).

The data reported here are derived from site measurements or from measurements made by laboratories contracted by Magnox Electric Ltd. These can be compared with the data reported in "Radioactivity in Food and the Environment, 2007" (RIFE 13) that are derived from monitoring programmes that are independent of the company.

This report continues to present annual discharge data over five years for all radionuclides specified in Radioactive Substances Act (RSA) authorisations. Disposal data and the results of environmental monitoring are presented for the report year, together with some information on trends, and radiological impact in terms of critical group and collective doses. Summaries of critical group doses are presented with results from the previous year for comparison.

1.2 Regulation of radioactive discharges and disposals

The control of radioactive wastes is subject to the provisions of the RSA 1993. Under this Act, operators are permitted to discharge and dispose of Radioactive Waste only in accordance with Certificates of Authorisation issued by the EA in England and Wales, and SEPA in Scotland. Many of the conditions laid down in these Certificates of Authorisation in force in England and Wales require that the operator shall carry out actions “as the EA may require”. The details of any such requirements are then specified in a separate document, the Compilation of EA’s Requirements (CEAR) that accompanies the Certificate of Authorisation.

It is the policy of these agencies to review authorisations regularly. In establishing discharge limits for authorisations, they take into account the radiation protection principles presented in the latest relevant Government White Paper (Table 6) (Reference 1). These principles are based on Government policy and the advice of the Health Protection Agency (HPA), Radiation Protection Division, as discussed below in the context of critical group dose limits and constraints (Section 1.4.2) and collective doses (Section 1.4.3). They were incorporated into UK law in the Radioactive Substances Basic Safety Standards Direction (BSS) 2000 issued by the appropriate ministers to the EA and SEPA so as to implement those parts of the Euratom Basic Safety Standards Directive (BSS) 1996 relating to dose limits (Section 1.4.2). Other provisions of the BSS Directive were implemented through the Ionising Radiations Regulations 1999 (IRR 1999).

Table 6 Summary of radiation protection principles in the Government’s review of radioactive waste management policy (1995) (Reference 1)
Annual Dose	Applicability	Comments
1000 μSv	Limits the overall exposure to the general public from man-made controlled sources of radiation (excluding medical uses), including the effects of past and current discharges and summing across all relevant exposure pathways.	The previous flexibility to average over more than one year is no longer considered necessary, and this limit is now a cap on annual exposure.
500 μSv	A ‘site constraint’ to limit the aggregate exposure from a number of sources with contiguous boundaries at a single location.	Applies irrespective of whether different sources on the site are owned or operated by the same or different organisations.
300 μSv	A ‘dose constraint’ used as the principal criterion in determining applications for discharge authorisations from new facilities. It applies to the sum of all relevant exposures resulting from the operation of a single new source only.	Existing facilities may seek a higher dose constraint in certain circumstances. In most cases, this should not be necessary and, in any case, the dose limit and As Low As Reasonably Achievable (ALARA) principle continue to apply.
20 μSv	Threshold for optimisation below which the regulators will not seek further reduction in public exposures, provided they are satisfied that ‘Best Practicable Means’ (BPM) are being applied to safeguard the public.	The introduction of this concept is consistent with the current practice of the Health and Safety Executive (HSE).

All discharges of radioactivity are subject to the requirement to use BPM to limit the amount of radioactivity discharged. The EA monitors the application of best practicable means by applying Quarterly Notification Levels (QNLs) to discharges of certain radionuclides. Exceeding a QNL requires the operator to submit a written justification of the BPM used to limit discharges. The EA and SEPA also require that discharge and disposal routes for new waste streams use the Best Practicable Environmental Option (BPEO) for disposal of that waste. Operators are also required to confirm that existing disposal practices use the BPEO.

From 2002, the EA has applied Weekly Advisory Levels ( WALs) to aerial discharges of certain radionuclides from generating stations. These replace weekly limits, which were intended:

to ensure that routine discharges from nuclear sites did not cause radioactivity in locally grown foods to exceed the European Community Food Intervention Levels (CFILs), intended to protect the public after a nuclear accident and
to ensure that annual doses did not exceed 300 µSv.

The EA has recognised that the very pessimistic assumptions used to derive the limits were unduly restrictive on station operations. Instead, the EA and Food Standards Agency (FSA) are notified as soon as an operator expects to exceed a WAL, allowing additional environmental monitoring to be considered. The WALs have been set at lower levels than the limits they replace, so there is a greater potential for them to be exceeded routinely, usually during statutory maintenance. WALs have not been applied to aerial discharges from defueling or decommissioning stations, as there is no potential for either CFILs to be exceeded or annual doses to exceed 300 µSv due to routine discharges from these sites.

Two statutory consultees have been appointed to the EA and SEPA in matters relating to radioactive discharge authorisations. The FSA has taken on the role of consultee formerly exercised by the Ministry of Agriculture Fisheries and Foods (MAFF). The functions of MAFF have been taken over by Department for Environment Food and Rural Affairs (DEFRA). Its responsibilities include food safety implications of discharges of Radioactive Waste, in support of which it undertakes a substantial radiological surveillance programme. The Nuclear Installations Inspectorate (NII) acts as the other consultee because it regulates the accumulation of radioactive waste on nuclear licensed sites and the exposure of the general public to direct radiation from those sites.

Specialist staff from the EA and SEPA regularly visit nuclear sites to inspect operations against radiological protection criteria. Thus the authorisation process is one of continual review. This process not only reviews operations, effluent control and discharge assessment methods, but also the results of environmental monitoring and radiological methodologies, to ensure that radiological impacts are assessed with the most up-to-date information.

Thus the authorisation and inspection process embraces important aspects of radiation protection by:

controlling, monitoring and recording discharges to the environment;
monitoring of the environment to establish resultant radionuclide concentrations;
predictive assessment of radiation doses to the public arising from future discharges to the environment (usually carried out as part of an application for an authorisation); and
retrospective assessment of radiation doses to the public.

The company is involved in all these activities with respect to discharges from its sites. Under the terms of the discharge authorisations, there is a statutory obligation to carry out defined monitoring programmes, both for discharges and for environmental radioactivity, the latter being known as Statutory Environmental Monitoring Programmes (SEMPs). From 2003, SEMPs in England and Wales were expanded to incorporate any additional monitoring carried out routinely by the company and specified in the relevant CEAR. In addition, the NII requires the assessment of doses to members of the public from direct radiation.

The EA and SEPA have recently adopted a three tier approach to enforcement action under the RSA 1993. For the most serious offences, the offender faces prosecution. Where prosecution is inappropriate, the regulators may serve an enforcement notice on the operator, who must then improve his performance under the RSA 1993 according to the precise terms of the notice. Finally, the SEPA and the EA have adopted a minimum response of a formal warning letter issued to an operator, where neither prosecution nor an enforcement notice are appropriate (for example, because the operator is already carrying out those improvements that would otherwise be detailed in an enforcement notice). Where an operator receives three warning letters in succession, then the regulator may consider serving an enforcement notice or commencing proceedings against the operator.

At the Ministerial meeting of the OSPAR Commission at Sintra in Portugal in 1998, the UK Government agreed to a commitment to reduce concentrations of radioactive and hazardous substances in the marine environment so that, by 2020, discharges will be reduced to levels where the resulting concentrations additional to historic levels are close to zero. Following consultation in 2002 on a proposed national discharge policy to meet these requirements, DEFRA published its ‘UK Strategy for Radioactive Discharges 2001-2020’. The Company is working with Government and regulators to achieve the objectives agreed at Sintra.

1.3 Regulation of non-radioactive discharges and disposals

The regulation of non-radioactive discharges and disposals is the responsibility of the EA, SEPA and local authorities who regulate discharges in accordance with the provisions of the:

Environmental Protection Act (EPA ) 1990,
Controlled Activities Regulations (CAR) 1 April 2006. This replaced The Control of Pollution Act 1974 (CoPA 1974)
The Water Resources Act 1991 (WRA 1991) as amended by the Environment Act 1995.

The exception is regulation of discharges to sewer, which are regulated by the relevant sewage undertaker (see below).

Prescribed Process permits are issued under the Pollution Prevention and Control Regulations 2000 (PPC), which implement the requirements of the EC Integrated Pollution Prevention and Control Directive (IPPC). They require detailed assessments of all environmental discharges from primary and directly associated activities on industrial sites. They also regulate matters such as energy usage, noise, odour and vibrations.

The control of discharges from ‘Prescribed Processes’ (EPA 1990) are made either:

under Pollution Prevention Control (PPC) permits, issued by the EA or SEPA; or
by Air Pollution Control Authorisations issued by Local Authorities or SEPA.

These ensure compliance with quality objectives and standards by specifying discharge limits and other conditions. There is also a requirement in these permits that Best Available Techniques (BAT) will be used to prevent, or where that is not practical to reduce, emissions from the installation. Where releases of a substance may affect more than one environmental medium, the authorisation must have regard to the BPEO.

Discharges to controlled waters of sewage or trade effluent, from processes not subject to EPA 1990 authorisation, are regulated through a system of consents under the WRA 1991 in England and Wales and the Control of Pollution Act 1974 (CoPA 1974) in Scotland. Where discharges of trade effluent are made to public sewers, they must be subject to a consent issued by the relevant sewage undertaker as required by the Water Industry Act 1991 in England and Wales and the Sewerage Scotland Act 1968. In granting consents, the regulatory agencies or sewage undertakers take account of Statutory Water Quality Objectives. Consents place limits on either total quantities discharged (loads) or on instantaneous concentrations.

Disposals of solid non-Radioactive Wastes are regulated through EPA 1990 and the Environment Act 1995., which amended the Waste Management Licensing Regulations 1994. These in turn replaced sections of the CoPA 1974. Where wastes are transferred to another organisation for disposal, there is a legal Duty of Care on producers, carriers and disposers to ensure that waste is disposed of only under the terms of a licence. Where waste is transferred, it is accompanied by a transfer note and a full written description of the waste. The Special Waste Regulations 1996 (as amended) place extra controls on wastes deemed hazardous under UK and EC regulations. Landfill disposals are now subject to the Landfill Regulations, which implement the requirements of the Landfill Directive and will place additional requirements on both landfill site operators and waste consignors.

1.4 Critical group and collective dose

1.4.1 Critical group doses

A key concept for assessment of dose to the public is the ‘critical group’. This represents those members of the public who are most exposed to radiation due to operations at a given site (References 2 and 3). The dose to a critical group is assessed as the mean of the ‘effective doses’ (see Glossary) to the individual members of the group. Effective dose to an individual is the sum of committed effective dose from intake of radionuclides during the year and from external irradiation over the same period. Committed effective doses are calculated from dose per unit intake data and from estimates of annual radionuclide intake by inhalation and ingestion. All relevant intake pathways are taken into account, including consumption of specific foods at high rates and inhalation doses from occupancy of certain areas (References 4 and 5). Consequently, the mean dose to the critical group provides a stringent assessment of radiation dose against limits or constraints.

In determining the critical group appropriate to a particular site, doses from different pathways should be summed as required to obtain the critical group dose. The relative magnitude of such pathway-specific doses will depend on the habits of particular groups of individuals. Thus a high rate consumer of seafood may receive only a minor exposure via pathways such as milk consumption. For another group, consumption of locally produced milk may combine with inhalation of radionuclides discharged to air to result in an elevated exposure. Accordingly, it is common practice to define exposure groups in terms of a dominant pathway or habit (e.g. seafood consumers, boat dwellers, anglers, inhalation pathways etc). For simplicity, these may at times be referred to in this report as ‘critical groups’, although strictly speaking the HPA (Reference 3) defines only the most exposed group at any given time as the critical group.

This report focuses mainly on doses to members of critical groups; the small groups of people that are most exposed to radiation from nuclear facilities. The doses received by the rest of the population from operations at Magnox sites will be very much less than those received by critical groups.

1.4.2 Critical group dose limits and constraints

Dose limits and constraints applicable to controlled releases of radioactivity are based on the ‘1990 Recommendations’ of the International Commission on Radiological Protection (ICRP) (Reference 2). Under these recommendations, the primary dose quantity was redefined as effective dose (see the Glossary), taking into account ‘weighting factors’ which reflect the sensitivity of different body organs to induction of cancer following exposure to radiation. For members of the public, the ICRP recommended an annual limit on effective dose of 1000 µSv.

The ‘1990 Recommendations’ also emphasised the optimisation of radiation protection (Section 1.4.3), by relating it to the concept of source-related restrictions on individual dose, termed ‘dose constraints’. A dose constraint is an upper bound on the annual dose to the overall critical group, summed over all exposure pathways, from the planned operation of a controlled source (Reference 3). Dose constraints may introduce restrictions additional to those required to meet the overall dose limit.

The HPA’s guidance, based on ICRP’s ‘1990 Recommendations’, recommended that the maximum dose constraint should be 300 µSv per year for proposed new controlled sources (Reference 3). Constraints lower than this could be set where such doses are readily achievable. Existing facilities are expected to operate within the appropriate constraints, if reasonably practicable. However, if this is not practicable, the HPA advise that the operating regime be reviewed with the regulatory body to ensure that doses are ALARA. Exposures arising from past controlled releases should be included in any comparison with the 1000 µSv dose limit but not in comparison with the dose constraint of 300 µSv. HPA advice included the caveat that doses should in any case be below the 1000 µSv limit on annual dose.

The 1000 µSv dose limit was incorporated into the Euratom Basic Safety Standards Directive 1996 and implemented in UK law through the Radioactive Substances Basic Safety Standards Direction 2000 (Section 1.2). Ministers have directed the EA and SEPA to ensure that the Directive limit on annual dose to the public is not exceeded, and that a maximum source constraint of 300 µSv y^-1 is applied for authorising radioactive discharges. Where more than one facility occupies a site, then an overall site constraint of 500 µSv y^-1 is applied to doses due to discharges from the site. The annual dose limit of 1000 µSv should be compared with the sum of doses from external exposure and internal exposure from intakes of radionuclides.

1.4.3 Collective doses

In addition to estimating doses to critical groups, doses to populations as a whole can be estimated (Reference 6). This involves the concept of ‘collective dose’: the summation of all individual radiation doses received by a population over some defined period of time. Since radionuclides persist in the environment, the public will continue to receive radiation doses for some time after a discharge is made, although generally at a decreasing rate due to processes of dilution, dispersion and radioactive decay. Calculating the collective dose therefore involves predicting the behaviour of radionuclides over extended periods following the discharge.

In practice, collective doses are often dominated by the summation of a large number of very small doses received by individuals who are remote, in both space and time, from the point of discharge. Consequently, the calculation of collective dose relies heavily on the use of theoretical models that predict the dispersion of radionuclides over large geographical areas and long time-scales. The unit for collective dose is the man sievert (man Sv) which emphasises that the value quoted is the sum of doses received by a number of individuals.

The time and geographical area over which a collective dose is integrated is necessarily stated with the estimated value. The HPA advice emphasises a 500 year integration period (Reference 7) and this is used throughout this report. Doses are generally calculated to the populations of UK, Europe (including the UK) and the world.

Collective doses play an important role in the optimisation of radiological protection using the ALARA principle. This is recognised by the HPA (Reference 3) as being a useful technique for aiding decisions between different options for radiological protection.

1.5 Monitoring of environmental radioactivity and dose assessment

The structure of the SEMPs (Section 1.2) reflects the emphasis placed on assessing radiation doses to the public in the areas local to Magnox Electric Ltd sites. The essential considerations are to:

Take account of the most important pathways by which radiation exposure of the public may occur;
Conduct appropriate sampling and analysis to determine radionuclide concentrations or radiation levels relevant to those pathways;
Combine the monitoring results with data on foodstuff consumption and other habits, and with data on the biokinetic behaviour of radionuclides, to yield estimates of radiation dose to the public.

It should be noted that these dose estimates, being based on environmental concentrations, will include contributions from radionuclides discharged in earlier years. Therefore, they will differ from dose estimates in technical submissions to authorisation reviews, which relate to projected doses at expected future levels of discharge and at proposed discharge limits.

Data identifying critical groups and their habits by pathway have been provided by the FSA, EA, SEPA and the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), or their predecessors, based on published survey work (References 8 and 9). Site-specific habits data used in dose assessments relate to the most recent published survey. Guidelines on generalised food consumption rates for use in radiological dose assessments (particularly for terrestrial pathways) were issued by MAFF (DEFRA) and HPA in 1995 (Reference 10). Where appropriate, such generalised advice may be supplemented by other HPA advice (Reference 11)

Throughout this report the guidance of HPA (Reference 3) and the most recent dose coefficients in ICRP Publication 72 (Reference 12) are adopted where available and appropriate. For the specific calculation of doses from argon-41, where the HPA does not provide advice, a cloud immersion dose is calculated from the recommendations of the ICRP (References 2 and 13). Default values recommended by the ICRP for each radionuclide are assumed for the purpose of dose calculations.

In accordance with regulatory guidance (Reference 14), radiation dose rates in air (‘air kerma’) are generally measured in primary units of µGy h^-1, the absorbed dose rate. In order to express this as a dose rate equivalent, µSv h^-1, a conversion factor of 0.86 µSv per µGy has been adopted (Reference 14). This reflects the differing energy deposition of ionising radiation in differing media: in this case air and tissue. By expressing the radiation dose rate in µSv h^-1 and making allowance for background dose rates, a direct estimate of the dose to man can be obtained.

Independent environmental monitoring programmes and dose assessments in areas both local to Magnox sites and further afield are carried out and reported by government agencies and other groups (References 8, 9 and 17 - 20).

Collective doses have been calculated, using a 500 year integration period (Section 1.4.3), based on the most recent European Union (EU) methodology (References 21 - 23). This approach is consistent with the dosimetric basis used to calculate critical group doses, as assessed by both Magnox Electric and independently by the FSA (Reference 8).

1.6 Analytical measurements, limits of detection and rounding of data

All measurements of radioactive discharges, concentrations of radionuclides in the environment and radiation dose rates are subject, as with any other type of measurement, to uncertainties arising from the measurement process itself. These may become important when the quantities involved are very small compared with the measurement uncertainty, and the result is then quoted as a ‘limit of detection’ (i.e. with a ‘<‘ sign). The EA has defined the ‘limit of detection’ required for environmental monitoring as reporting with a 95% probability of detection (i.e. 5% uncertainty) for a single measurement. This definition is laid down in the CEARs. Strictly, a ‘limit of detection’ takes account of all the contributions to uncertainty, from sampling uncertainties, through those introduced during sample processing to uncertainties due to the actual analysis. In this report, only the analytical uncertainties are included, so the quantity is termed the ‘minimum detectable activity’ (MDA) to distinguish it from a true ‘limit of detection’.

For clarity of presentation (and after calculations have been completed), discharge, concentration and dose rate data are normally rounded to two significant figures, or just one where the numbers are very small.

Results from Magnox Electric’s environmental monitoring programmes are reported here as the arithmetic means of measurements taken throughout the year. The concentrations of many radionuclides in the environment are now consistently below the level at which it is practicable to make positive determinations. They continue to be included in the monitoring and analysis programmes for reassurance that new pathways involving, for example, remobilised historical materials, have not arisen. Dose calculations conservatively use such ‘minimum detectable activity’ (MDA) values.

It should also be noted that measurements of ‘total α’, ‘total β' and ‘other activity’ do not necessarily equate to the sum of individually measured radionuclides. This is because of differing counting efficiencies and the presence of naturally occurring radioactive isotopes.

1.7 Natural radioactivity

To put into context the data presented in this report, it is important to recognise that natural radioactivity is the dominant source of radiation exposure to the population as a whole, including individuals living close to nuclear establishments. The widespread radioactive fallout from the testing of nuclear weapons and from Chernobyl also contributes to doses. The subject has been reviewed comprehensively by the HPA (References 15 and 16) and others (Reference 26).

Individual doses from natural radioactivity in the UK range broadly from 1000 µSv to 100,000 µSv per year (Reference 15). The upper end of the range stems from homes with particularly high indoor levels of radon and its decay products. Dose limits set for the industry do not apply to natural background radiation, such as that from radon. Nevertheless, it may be noted for comparative purposes only, that these upper figures exceed the dose limits to the public applicable to the operation of nuclear establishments a hundred fold (see Sections 1.1, 1.4.2 and Table 6). The HPA suggests that a radon-222 concentration of 20 Bq m^-3 corresponds to an annual dose of 1000 µSv and recommends that measures be taken to reduce radon in levels in homes if the average annual indoor activity concentrations exceed 200 Bq m^-3 (Reference 15).

The measurements in this report relate to environmental radioactivity that is mainly attributable to discharges from Magnox sites. However, natural radioactivity makes an appreciable contribution to the reported values in some instances. Where it is practicable to do so, the appropriate correction is made and noted. Thus, gamma dose rates quoted in this report are total dose rates including natural terrestrial background and cosmic ray contributions. For dose assessment purposes, the natural contributions are deducted. Dungeness A, Hinkley Point A, Hunterston A and Sizewell A are all adjacent to the B sites operated by British Energy, discharges from which will all add to the discharges reported for the Magnox sites. However, no attempt is made to correct for this contribution, unless the Magnox site is defuelling or decommissioning, in which case any contribution from short-lived radionuclides is discounted (Section 1.6).

A comparison of annually averaged doses to individuals in the UK population from all sources of radioactivity is presented in Table 7. Typically, natural background accounts for some 84% of the total dose, medical uses of radiation for 15%, occupational exposure for 0.2%, nuclear weapons fallout for 0.2% and only 0.04% from discharges and disposals, including those from the nuclear industry (Reference 36). On this basis, the annual average dose in the UK from all natural sources is around 2200 µSv, although in areas of higher natural background radiation (e.g. Cornwall), this may exceed 6000 µSv (Reference 16).

Table 7. Summary of doses to the UK population from natural sources (Reference 36)^a
Source	Average Annual dose (µSv)
Source	Previous estimate	Present estimate	Range
Cosmic radiation	320	330^b	200 – 400^c
Terrestrial gamma radiation	350	350	100 – 1000
Irradiation from internal radio-nuclides	270	250	100 – 1000
Exposure to radon and progeny	1200	1200	300 – 100,000
Exposure to thoron and progeny	100	100	50 – 500
Total	2240	2230	1000 – 100,000

Table reproduced (with minor presentational changes) by kind permission of HPA
Including an additional 30 µSv from air travel, which is increased from 20 µSv in the previous review. It should be noted that not all of the population is exposed to this source.
Range does not include air travel

2.0 Operations at generating, defuelling and decommissioning sites

2.1 Nuclear

Magnox reactors generate electricity by nuclear fission. The fuel is held in the reactor core as an array of natural uranium bars, each encased in Magnox, an alloy of magnesium and aluminium. The array is enclosed in a graphite matrix (the moderator). The hot core is cooled with carbon dioxide, which generates steam in the boilers before being routed back to the core. The steam is then passed through turbines to generate electricity.

Stations are equipped with a variety of plant to control the chemical purity of the coolant, both to prevent the accumulation of chemicals that might inhibit power generation and to maximise the generating life of the reactor. In particular, the quantities of carbon monoxide, moisture and nitrogen in the coolant are limited. Carbon monoxide can be controlled by purging the coolant with clean carbon dioxide or by using a recombination unit to convert carbon monoxide to carbon dioxide on a catalyst. The recombination unit also converts gaseous species of hydrogen to water, thereby removing moisture from the coolant. In the process, tritium is converted to tritiated water. Moisture may also be removed by dryer units. Any tritiated water drained from the recombination unit or dryer unit is discharged as liquid effluent (Section 3.1).

The coolant is circulated through the core at high pressure (10 to 30 bar), so each reactor is enclosed in a pressure vessel. The older Magnox reactors have steel pressure vessels, which require an external concrete biological shield to protect station personnel from radiation. The interspace between the steel and the concrete was swept by air to cool the shield. This air was then discharged. These older reactors are now all shutdown. The more recent stations (Oldbury and Wylfa) have pre-stressed concrete pressure vessels that provide adequate protection to personnel from radiation and so require no additional biological shield. These concrete pressure vessels are water-cooled, so do not discharge shield-cooling air.

Where appropriate, contamination controlled areas in each site are served by ventilation systems equipped with high efficiency filters to minimise the aerial discharge of radioactive particles.

After about five years in the reactor, irradiated fuel is removed, then cooled for about 90 days to meet transport regulations and sent to Sellafield for reprocessing. It is cooled under water, except at Wylfa, which has a dry storage system (Section 3.2.5).

2.2 Operations at generating and defuelling sites

2.2.1 Chapelcross

The four cooling towers were demolished by controlled explosive demolition during May 2007. Extensive sampling had been carried out before demolition to demonstrate the towers did not constitute "radioactive waste" and the resulting rubble was crushed and used to in-fill the tower basins.

Also during 2007 the Fuel Route Transition Project continued to convert to a "dry" route in advance of defuelling. Also an attempt was made to remove scale from inside the effluent pipeline. Unfortunately, unprecedented weather conditions resulted in the cleaning attempt being abandoned.

There were three events during 2007 in which discharge limits were breached: two events were not associated with radioactivity. These were:

On 21st February an effluent discharge sample was found to have a TSS content of 132 mg/l, exceeding the limit of 100 mg/l. This breached the CoPA consent. The regulator (SEPA) was informed and no further action taken.

On August 16th an effluent discharge sample was found to have a TSS content of 144 mg/l, exceeding the limit of 100 mg/l. This breached the CoPA consent. The regulator (SEPA) was informed and no further action taken.

On 15th August following routine operations at the effluent pipeline a piece of contaminated limescale was detected on the foreshore. It was assumed that this was due to historic discharges. The regulator (SEPA) was informed and no further action taken.

2.2.2 Dungeness A

Generation ceased at the end of 2006 and the site entered the Post Operational Defuelling phase of operations.

A legacy waste removal campaign was completed during 2007. Throughout the campaign great efforts were made to size reduce, decontaminate and segregate waste.

De-planting of both of Dungeness A’s CO₂ plants was completed. All four CO₂ tanks were de-lagged, removed from site and sold on for refurbishment. This resulted in 148 tonnes of steel for direct re-use. All other metal was segregated and sent for recycling at EMR (European Metal Recycling).

Approximately 80 tonnes of solid waste was cleared from site via the site's clearance monitoring process. Improvements have been made to the equipment used for making measurements as part of this process which will lead to increased accuracy and reliability in the measurements.

Dungeness A successfully emptied and processed the contents of its splitter vaults. This was completed in 2007, a year ahead of schedule. All secondary waste, mainly sludge, was encapsulated and disposed of to the Low Level Waste Repository (LLWR).

There were four occasions on which the QNL was exceeded. This was the result of a planned disposal programme of tritiated water from the reactor gas recombination units as agreed by the EA Site Inspector.

2.2.3 Oldbury

Reactor 1 was shutdown for all of 2007 and Reactor 2 was shutdown until August 2007. The outages were conducted for routine maintenance including extensive core graphite sampling, which was required for the preparation of safety cases for contined operation.

Oldbury maintained Level 8 rating in both International Safety Rating System (ISRS) and International Environmental Rating System (IERS) during 2007.

Oldbury reported to the EA on a quarterly basis that they had exceeded their caesium-137 QNL; the Site had submitted a full BPM report for the justification for doing so and has controls in place. Caesium-137 levels in the Oldbury ponds have increased due to the transfer of caesium-137 from incoming Sellafield skips.

2.2.4 Sizewell A

Generation ceased at the end of 2006 and the site entered the Post Operational Defuelling phase of operations.

The QNL for aqueous tritium disposals from Sizewell A Power Station was exceeded in January 2007 following the discharge of a Final Monitoring and Delay Tank (FMDT) containing the contents of a Gas Conditioning Plant tritiated water collection vessel. This was a planned action and pre-notified to the Environment Agency

The WAL for carbon-14 in gaseous discharges was exceeded in January 2007 following the planned double shutdown of both reactors. As this was pre-planned due to the cessation of generation a notification was made to the Environment Agency and Food Standards Agency prior to the WAL being exceeded

Significant work was progressed into the options for removal of radioactive wastes from site. All of these initiatives are being performed with full engagement of the regulators and, in respect of Fuel Element Debris, with a wide group of Site Stakeholders participating in the Options Assessment Panel. This process has been identified as good practice by the Sizewell Site Environment Agency Inspector and will ensure that options for disposal are discussed and optioneered by all relevant parties.

There was a Site Incident in January 2007 involving a failure of the pond water recirculation pipe line. This is a well documented event that was fully investigated by the regulators. There was no increase in radiological aqueous discharges and as a consequence no radiological discharge notification levels or limits were exceeded as a result of this site incident. The site has made extensive efforts to ensure the replacement system and associated alarms are robust and fit for purpose. This has used the rigorous company modification process, which requires input, assessment and approval by suitable RSA93 qualified experts and environmental professionals at all levels of the modification process, planning and implementation.

There was a limited release of material from a Magnox fuel element into the cooling ponds in 2007. This situation has been well documented through interaction between site and the regulators. Use of BPM was reviewed and optimised at all stages of the management of this event. This involved the use of innovative and bespoke techniques, with input from site operations/engineering and radiological protection experts to minimise the release of radionuclides into the cooling pond. No radiological discharge notification levels or limits were exceeded as a result of this event and there was no significant increase in radiological discharges to the environment.

In September 2007 a four day audit was undertaken by representatives from the Environment Agency and the Sizewell A Site Nuclear Installations Inspector in September. The audit team concentrated on radioactive waste disposal and related areas. A draft audit report was forwarded to site staff for comment. Where areas for improvement were noted and agreed, the site developed an action plan to address these.

2.2.5 Wylfa

Reactor 1 was shut down for a statutory outage from April to August 2007. Both reactors were otherwise at nominal full power for most of the year although each reactor experienced periods of reduced power or shutdown to address boiler and turbine performance issues.

The Reactor 1 outage resulted in the Weekly Advisory Level for tritium and carbon-14 being exceeded due to the reactor blowdown and purge.This is a routine event on entering an outage. Two environmental survey results exceeded four standard deviations of the previous 12 readings. Neither instance was attributable to on site activities. Each event was reported in line with company and Environment Agency requirements. There were no other significant environmental events during 2007.

2.3 Operations at decommissioning sites

2.3.1 Berkeley Nuclear Licensed Site

Berkeley Nuclear Laboratories were established in 1961 to provide technical support for the operation of nuclear power stations. Later the site was known as Berkeley Technology Centre and later still Berkeley Centre. It provided shielded facilities for post-irradiation examination of nuclear materials and irradiated fuel. It also had facilities for other work with radioactive materials. Eleven hectares of the 27 hectares site was delicensed at the end of 2006. The remaining parts the site including the power station and the shielded facilities have been relicensed as a single site, Berkeley Nuclear Licensed Site (BNLS) and it is planned to put the site into a safe and compliant state (SCS), a safe and secure site (S3), and then into Care and Maintenance. Berkeley Centre therefore will not be reported in radiological sections of this report.

In March a warning letter was received from the EA noting that it was observed that work was being undertaken in the caesium removal plant building whilst the gaseous discharge monitoring system was not functioning. The matter was promptly resolved and no further action was taken.

In May a second warning letter was received from the EA. This concerned the overflow of the ebb tide tank within the Active Efflent Treatment Plant (AETP) on 20th March. An embargo was placed on the use of the AETP until the cause of the overflow was identified and modifications to plant and procedures made to prevent an overflow happening again. No further action was taken by the EA.

No QNLs were exceeded during the year.

2.3.2 Bradwell

Defuelling was completed in 2006/07 with the removal of 99% of radioactivity from site and the reduced use of the fuel cooling ponds. This is reflected in the significant reduction in radioactive liquid discharges (Table 15).

To reduce the environmental impact of discharges from the pond water treatment plant, its use was restricted during the initial phases of the pond clean up work.

No QNLs or WALs were exeeded during the year.

2.3.3 Hinkley Point A

The decommissioning programme for Hinkley Point A site was progressed. A significant highlight was the successful outcome of trials to identify the Best Practicable Means (BPM) for the disposal of more than 1000 ILW Pond Skips. The optimum solution was assessed to be on-site decontamination to LLW, by ultra high pressure water jetting to remove highly active surface paint, followed by trans-frontier shipment of the processed skips for metal melting at the Energy Solutions smelting facility at Oak Ridge, Tennessee, USA. Metal melting enables the recovery of metal for beneficial reuse. This route represents the first authorisation for bulk shipments granted in the UK, under the 2007 Defra long term management of solid low level waste policy.

Focus was also directed towards improving the assessment of radioactive discharges to the environment. The protocol for sampling reactor gas during generation and defuelling phases involved the oxidation by air at 1100ºC to ensure conversion of tritium to tritiated water (HTO) and ¹⁴C to ¹⁴CO₂. Trials were carried out that successively demonstrated that as the reactors are now vented to atmosphere, oxidation effectively occurred in-situ and therefore use of a furnace to heat sampled air to 1100°C was no longer required. Discontinuing use of the furnace was therefore assessed to represent BPM in view of the reduction in the use of consumables, electricity and process simplification Further trials were also successfully carried out to validate the replacement of sulphur-35 trolleys with more modern Total Tritium Oxidation Units (TTOUs) for sampling reactor gas.

An external United Kingdom Accreditation Service (UKAS) audit was undertaken in October 2007, as part of the efforts by the site to retain accreditation to the ISO 9001 standard, and achieve accreditaion to the 140001 and 18001 standards. The site was successful in obtaining accreditation to all three standards”.

No QNLs or WALs were exceeded during 2007.

2.3.4 Hunterston A

Hunterston A continued with its decommissioning programme focussing on the following areas:

Completion of characterisation of the sites contaminated land inventory and commencement of the first stages of development of future remediation and managment options; Commissioning of plant to be used for decontamination and disposal of aluminium fuel element storage skips in the Cartridge Cooling Pond; Non-active commissioning of the Modular Active Effluent Treatment Plant; ILW Store completion and start of non-active commissioning; First stages of Temporary Weather Barrier installation.

The site retained its certification to ISO14001.

2.3.5 Trawsfynydd

The decontamination of the site’s fuel cooling ponds with a robotic scabbling system continued. The scabbled LLW powder and rubble concrete waste produced was remotely packed into Scabbled Waste Containers (SWC) for transfer to LLWR. Innovative methods of co-packaging the SWCs with other LLW wastes were developed during 2007 to ensure that the site was able to make the most effective possible use of the site’s LLWR activity and volume allocation.

A significant reduction of the volume of waste classified as Intermediate Level Waste (ILW) was achieved as a result of detailed surveys of certain Site waste vaults by Health Physics personnel. The reclassification of this waste as LLW removed the need for the development of a remotely controlled robotic waste retrieval system for this particular waste stream.

Residual unused polymer encapsulation material left after the completion of this effluent treatment retrieval campaign was transferred to another industrial user of the material for re-use. The surplus material was disposed of as Hazardous Waste (by high temperature incineration) after the completion of previous campaigns.

Work to clear accumulated sludge within the main site drains system was begun. The volume of sludge that had accumulated in certain parts of the system was greater than had been foreseen and not all of the work was completed during 2007. However, most of the drains system was cleaned out during 2007. Dedicated storage facilities for the storage of the sludge removed from the oil separator were constructed to facilitate future sludge removal. General site awareness of non-radiological environmental impacts on the Site’s effluent and drainage systems associated with decommissioning work continued to improve.

The Site’s Environmental Management System continued to be accredited to ISO 14001.

3.0 Radioactive discharges and disposals

All Magnox sites are authorised to discharge liquid waste to local water bodies (sea, estuary or lake as appropriate), gaseous waste to the atmosphere and to send low level radioactive solid waste for disposal at the national Low Level Waste Repository (LLWR). Several Magnox sites hold authorisations to dispose of combustible low level waste and oil, either by incineration on site or by transfer elsewhere for incineration under contract. Any radioactive ash generated is sent to the LLWR as low level waste.

3.1 Liquid discharges

Radioactive liquid wastes from Magnox sites consist mainly of tritium (which has minimal radiological impact and toxicity) with a variety of activation and fission products arising from the active effluent treatment plant and the fuel cooling ponds. Tritium arises mainly as water condensed from the gas circuit in gas dryers or recombination units (Section 2.1). Where volumes are small, a site is able to accumulate tritiated water over several years before discharge, so as to reduce discharges of tritium and other shorter-lived radionuclides, such as sulphur-35 (half-life 87 days), which arise in the gas circuit. However, the annual discharge of tritium then increases in a year when tritiated water is eventually discharged. Tritium is so mobile that it escapes from fuel even in the cooling ponds, so it continues to dominate the quantity of radioactivity in liquid discharges at defuelling sites that no longer generate tritiated liquid waste from the gas circuit. Discharges of tritium are much smaller from decommissioning sites once all the fuel has been removed, although some increase is likely when cooling ponds are drained and during the decommissioning of gas drying plant.

Small quantities of fission products are released to the cooling ponds from residual traces of irradiated uranium on the outside of the fuel cans and from low level leakage from fuel elements arising from minor damage to the fuel cladding. Corrosion of the Magnox alloy cladding is enhanced by dissolved ions in the cooling pond, particularly by negatively charged ions (anions), so the chemistry of the pond water is controlled to minimise corrosion of the fuel clad and any subsequent leakage of fission products into the ponds. The treatment plants are variously equipped with:

• filters, because suspended particles encourage corrosion where they settle on the fuel,
• coolers, because corrosion accelerates with temperature, and
• ion exchange plant, to minimise the concentration of dissolved anions.

Most anion beds are effective only if positively charged ions (cations) are also controlled, so separate cation beds are provided. As these ion exchange beds accumulate ions from the pond water, they become progressively less efficient and need regular regeneration with acid or alkali (typically daily). The ion exchange materials may then be reused. The used acid and alkali are neutralised and discharged. Any fission products released from the fuel also adsorb onto the ion exchange materials and are discharged with these neutralised liquors, hence the efforts to minimise the release of fission products from the fuel. Radionuclides discharged with neutralised liquors from the cation beds include caesium-137 and strontium-90, whereas those discharged with neutralised liquors from the anion beds include sulphur-35, ruthenium-106 and antimony-125. Sites are also equipped with plant for the treatment of radioactive effluents from the controlled areas such as those from bays where the fuel transport flasks are washed down before dispatch to Sellafield. Caesium-137 is the most significant fission product discharged, so sites have additional caesium abatement plant (depending on need, pond conditions and available pond space) to minimise discharges of radio-caesium from the ponds. Used ion exchange materials from the caesium abatement plant are stored as intermediate level waste.

Activation products in liquid waste derive from the gas circuit (as does tritium) and are discharged as either tritiated waste (Section 2.1) or via the active effluent treatment plant.

At most Magnox sites, quantitative limits apply to annual discharges of tritium, caesium-137 and ‘other activity’. Exceptions are discussed under the individual site Sections.

Liquid effluents are sampled prior to discharge and the levels of radioactivity are assessed to ensure that discharge of the effluent will comply with the relevant limits and that BPM are applied. The effluent is then discharged via a pipeline that discharges via an outlet specified in the authorisation (usually with the cooling water). Samples proportional to the total discharge are taken from the discharge pipe and analysed by the site for those radionuclides subject to quantitative limits to demonstrate compliance. For quality assurance purposes an external contractor performs the same analyses on representative samples of sites' effluents and the results are presented in Tables 8 to 18.

Samples of effluent that are representative of the annual discharge from each site are subject to extended radiochemical analysis by an external contractor, as required by the EA. Such requirements are set out in the CEAR issued to each site in England and Wales under the Certificate of Authorisation. Results of these analyses are included in Tables 8 to 18 under ‘Other radionuclides’. If the method to determine ‘other activity’ (based on β analysis) is sensitive to an equilibrium daughter radionuclide as well as its parent, then both are listed in Tables 8 to 18. Thus, the daughters yttrium-90, rhodium-106 and praseodymium-144 are listed as well as their parents strontium-90, ruthenium-106 and cerium-144. However, if the method to determine ‘other activity’ is sensitive only to the parent, then the daughter is excluded from the Tables. Therefore, caesium-137 and antimony-125 are included, but barium-137m and tellurium-125m (their respective equilibrium daughters) are not. Zirconium-95 and its daughter niobium-95 are both listed, as they are not in equilibrium in liquid effluent from Magnox sites. There are fewer data for ‘other radionuclides’ for Chapelcross and Hunterston A because these sites are regulated by SEPA, which imposes slightly different requirements.

3.2 Discharges from generating and defuelling power stations

All liquid discharges were within relevant quantitative limits in 2007.

Except at Wylfa (Section 3.2.5), ‘other activity’ in liquid discharges is dominated by the fission product strontium-90 (in equilibrium with yttrium-90), and the activation product sulphur-35. The latter has by far the lowest radiological impact. Sulphur-35 is relatively short-lived (Section 3.1), so is far less significant in discharges from defuelling stations.

3.2.1 Chapelcross

Chapelcross has no active effluent treatment plant, but uses ion exchange filtration intermittently and mesh filters on the discharge pipeline to the Solway Firth. The pipeline carries intermittent discharges from the pond and overflow water from the four cooling towers. When the reactors were operating the intermittent discharges from the Pond and CXPP, carried by the pipeline, were diluted by overflow river water from the cooling towers. With the closure of the reactors in 2004 and the final emptying of the cooling tower basins of river water in 2006, liquid effluent discharges have been diluted with towns mains water.

Radioactive liquid discharges over the past five years are shown in Table 8. Discharges of tritium, ‘total α’ and ‘total β’ activities are subject to authorised limits. Chapelcross does not have any QNLs for liquid or aerial discharges. However, the site does have a monthly notification level for 'all radionuclides other than α emitters and tritium' for liquid discharges but these were not exceeded in 2007.

Discharges in 2007 were similar to those in previous years.

Table 8. Liquid radioactive discharges from Chapelcross
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	0.25	0.08	0.033	0.011	0.0082	5.5
Total β^b	0.18	0.039	0.0049	0.0036	0.00098	25
Total α^b	0.0008	0.00003	0.00001	0.00001	0.000017	0.1
Other Nuclides	Annual discharge (GBq)
Sulphur-35	6.7	<0.4	<0.02	<0.02	<0.03
Cobalt-60	1.6	0.059	0.026	0.031	0.0091
Zinc-65	<0.05	<0.003	<0.001	<0.001	<0.001
Strontium-90	81	10.3	1.2	1.2	0.34
Ruthenium-106	<0.6	<0.04	<0.03	<0.006	<0.008
Antimony-125	0.4	<0.05	<0.007	<0.006	<0.003
Caesium-134	3.2	0.51	0.051	0.016	0.006
Caesium-137	36	7.6	1.3	0.52	0.38
Cerium-144	<0.3	<0.02	<0.006	<0.006	<0.005
Europium-154	<0.1	<0.01	<0.003	<0.002	<0.001
Americium-241	-	-	-	-	0.0096

Applies to any period of 12 consecutive months.
“Total β and total α” refer to specified analytical determinations. They do not reproduce precisely the contributions from individual radionuclides.

3.2.2 Dungeness A

In addition to the routine liquid effluents Dungeness A operates a dissolution plant for the disposal of waste Magnox splitters and lugs that have been removed from the fuel elements prior to dispatch to Sellafield. This debris is dissolved in carbonic acid (mains water saturated with carbon dioxide) which is then discharged to the sea. Magnox metal is an alloy of magnesium, (the second most common dissolved metal occurring naturally in seawater) and aluminium, so these discharges have negligible environmental impact. As there is very little radioactivity associated with the splitters and lugs, the radioactive discharges from this plant constitute a minor proportion of the site total.

Radioactive liquid discharges from Dungeness A over the past five years are shown in Table 9. The discharge from the dissolution plant is added to the FMDT discharge. The quantity of tritium discharged is high due to the disposal of carboys containing tritiated liquor from the condensate tank. There were four occasions on which the QNL was exceeded. This was the result of a planned disposal programme of tritiated water from the reactor gas recombination units as agreed by the EA Site Inspector.

Only about 0.3 % of the radioactivity in liquid discharges from the site arose from the Magnox dissolution plant tank MDT in 2007. In addition to caesium-137, only four radionuclides were detectable in this effluent. However, for consistency the reported minimum detectable activities for both the FMDT and MDT were converted to activity discharged and added. These are reported in Table 9 as "<".

The significant reduction in sulphur-35 and other short lived radionuclides is a result of the cessation of generation at the end of 2006.

Table 9. Liquid radioactive discharges from Dungeness A
Radionuclide	2003 ^b	2004^b	2005^b	2006^b	2007^b	Authorised limit (TBq) ^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	0.33	0.27	1.41	2.7	3.28	8
Caesium-137	0.34	0.17	0.12	0.079	0.07	1.1
Other activity ^c	0.17	0.1	0.08	0.09	0.022	0.8
Other radionuclides	Annual discharge (GBq)
Sulphur-35	75	64	74.7	83.9	4.64 ^e
Calcium-45	<0.23 ^e	<0.095	<0.22 ^e	<0.05	<0.04
Manganese-54	<0.14	<0.091	<0.053	<0.03	<0.07
Iron-55	<0.24 ^e	<0.081	<0.078	0.2 ^d	1.25 ^d
Cobalt-58	<0.24	<0.11	<0.054	<0.056	<0.075 ^e
Iron-59	<0.7	<0.3	<0.23	<0.18	<0.2 ^e
Cobalt-60	<0.27 ^d	<0.2 ^d	<0.07 ^d	1.2^d	2.15 ^d
Zinc-65	<0.39	<0.3	<0.14	<0.17	<0.2
Strontium-90	12	1.89	2.23	0.81^d	<2.19
Yttrium-90	12	1.89	2.23	0.81 ^d	<2.19
Zirconium-95	<0.6	<0.4	<0.25	<0.2	<0.19 ^e
Niobium-95	<0.6	<0.3	<0.21	<0.4	<0.2 ^e
Ruthenium-106	<2.5	<1.53	<0.769	<0.54	<1.02
Rhodium-106	<2.5	<1.53	<0.769	<0.54	<0.02
Silver-110m	<0.2	<0.2	<0.052	<0.057	<0.09
Antimony-124	<2.53 ^e	<2.56 ^e	<3.21 ^e	<4.31	<0.25 ^e
Antimony-125	<2.8 ^e	<2.36 ^e	<1.79 ^e	1.32^d	4.88 ^d
Tellurium-125m	<0.65 ^e	<0.54 ^e	<0.41 ^e	0.3 ^d	1.12 ^d
Caesium-134	<98 ^e	40.5	<20.4 ^e	11.7^d	<10.85
Cerium-144	<1	<0.88	<0.627	<0.4	<0.56
Praseodymium-144	<1	<0.88	<0.627	<0.4	<0.56
Europium-154	<0.2	<0.15	<0.059	<0.057	<0.09
Europium-155	<0.3	<0.13	<0.159	<0.1	<0.15
Plutonium-238	<0.037 ^e	<0.0097 ^e	<0.0026 ^e	<0.0017	<0.0042
Plutonium-239+240	0.052	<0.013 ^e	<0.004 ^e	<0.002	<0.004
Plutonium-241	2.8	<0.71 ^e	<0.2 ^e	<0.11	<0.3
Americium-241	0.032	<0.008 ^e	<0.002 ^e	<0.0014	<0.004
Curium-242	<0.005	<0.004	<0.0016	<0.001	<0.002
Curium-243+244	<0.003 ^e	<0.002	<0.001	<0.0006	<0.0006

Applies to a period of 12 consecutive months.
“Other radionuclides” includes discharges from the Magnox dissolution plant.
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.
Other radionuclides present in effluent from the Magnox dissolution plant at levels above the limit of detection.
Measurements of short lived radionuclides derived from analysis of the four quarterly bulk samples

3.2.3 Oldbury

There is no mechanism at Oldbury for the removal of gaseous activity to the liquid waste stream. Instead, tritium is discharged to air preferentially by the liquefaction plant (Section 3.4.1.3).

Discharges of caesium-137 have been steady since 2002 following a period of higher discharge between 2000 and 2002. This is caused by caesium-137 contamination from incoming Sellafield skips. Oldbury reported to the EA on a quarterly basis that they had exceeded the caesium-137 QNL; the Site had submitted a full BPM report for the justification for doing so and has controls in place.

Table 10. Liquid radioactive discharges from Oldbury
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq)^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	0.33	0.25	0.32	0.15	0.18	1
Caesium-137	0.45	0.39	0.42	0.40	0.38	0.7
Other activity ^b	0.22	0.21	0.18	0.11	0.17	0.7
Other radionuclides	Annual discharge (GBq)
Sulphur-35	120	87.2	67	31	5.37
Calcium-45	3.7	2.5	1.89	0.72	2.23
Manganese-54	< 0.2	< 0.06	< 0.08	<0.062	<0.05
Iron-55	0.32	0.19	<0.09	<0.054	<0.13
Cobalt-58	< 0.2	< 0.1	< 0.1	<0.067	<0.09
Iron-59	< 0.6	< 0.2	< 0.2	<0.23	<0.19
Cobalt-60	0.18	0.19	0.13	0.091	0.07
Zinc-65	< 0.3	< 0.2	< 0.2	<0.17	<0.16
Strontium-90	55	107	107	68.6	117
Yttrium-90	55	107	107	68.6	117
Zirconium-95	< 0.6	< 0.3	< 0.2	<0.24	<0.22
Niobium-95	< 0.7	< 0.2	< 0.2	<0.21	<0.19
Ruthenium-106	< 3	< 1	< 2	<1.4	<1.6
Rhodium-106	< 3	< 1	< 2	<1.4	<1.6
Silver-110m	< 0.2	< 0.1	< 0.1	<0.1	<0.08
Antimony-124	2.2	2.0	1.9	0.87	0.23
Antimony-125	< 0.8	< 0.7	< 0.7	0.94	<0.7
Tellurium-125m	< 0.2	< 0.2	< 0.2	0.21	<0.17
Caesium-134	120	50	46	74	40
Cerium-144	< 2	< 0.9	< 0.8	<0.97	<1.1
Praseodymium-144	< 2	< 0.9	< 0.8	<0.97	<1.1
Europium-154	< 0.2	< 0.1	< 0.1	<0.1	<0.05
Europium-155	< 0.4	< 0.2	< 0.2	<0.2	<0.31
Plutonium-238	0.0061	0.0028	0.0042	0.0021	0.0031
Plutonium-239+240	0.016	0.0054	0.012	0.0053	0.0072
Plutonium-241	0.60	0.14	0.35	0.36	0.49
Americium-241	0.029	0.016	0.024	<0.006	0.02
Curium-242	< 0.003	<0.002	<0.002	<0.0009	0.002
Curium-243+244	< 0.003	< 0.001	0.0007	<0.0003	0.0012

Applies to any period of 12 consecutive months.
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.2.4 Sizewell A

Radioactive liquid discharges from Sizewell A over the past five years are shown in Table 11.

Compared with previous years there are elevated aqueous discharges of tritium mainly because of a scheduled gas drier liquor disposal early in 2007 which resulted in the tritium QNL being exceeded.This was a planned action and pre-notified to the Environment Agency. Caesium -137 discharge levels have decreased. This is partly due to the unavailability of the treatment plant following the recirculation line failure but also strongly demonstrates the further optimisation of use of BPM in the management of contaminated fuel skips and the previously mentioned leaking fuel element (Section 2.2.4).

The significant reduction in sulphur-35 and other short lived radionuclides is a result of the cessation of generation at the end of 2006.

Table 11. Liquid radioactive discharges from Sizewell A
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq)^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	2.8	0.78	0.26	0.92	2.1	11
Caesium-137	0.56	0.61	0.65	0.57	0.26	1
Other activity^b	0.33	0.35	0.41	0.4	0.16	0.7
Other radionuclides	Annual discharge (GBq)
Sulphur-35	92	51	73	79	4.23
Calcium-45	4.4	2.3	1.8	1.9	1.19
Manganese-54	< 0.1	< 0.06	< 0.06	<0.056	<0.047
Iron-55	1.1	0.3	0.237	0.67	0.26
Cobalt-58	< 0.2	< 0.1	< 0.09	<0.09	<0.079
Iron-59	< 0.5	< 0.2	< 0.3	<0.3	<0.22
Cobalt-60	0.38	0.16	0.14	0.26	0.083
Zinc-65	< 0.3	< 0.2	< 0.2	<0.2	<0.17
Strontium-90	85	102	151	147	60.5
Yttrium-90	85	102	151	147	60.5
Zirconium-95	< 0.5	< 0.3	< 0.3	<0.3	<0.28
Niobium-95	< 0.5	< 0.2	< 0.3	<0.3	<0.2
Ruthenium-106	< 3	< 2	< 1	<3	<1.3
Rhodium-106	< 3	< 2	< 1	<3	<1.3
Silver-110m	< 0.2	< 0.1	< 0.1	<0.2	<0.075
Antimony-124	1.2	0.74	1.17	2.3	<0.1
Antimony-125	< 0.9	< 0.8	< 0.7	<0.7	1.18
Tellurium-125m	< 0.2	< 0.2	< 0.2	<0.2	0.27
Caesium-134	110	106	80	62	40
Cerium-144	< 2	< 1	< 1	<2	1.87
Praseodymium-144	< 2	< 1	< 1	<2	1.87
Europium-154	< 0.2	< 0.09	< 0.08	<0.05	0.21
Europium-155	< 0.4	< 0.3	< 0.4	<0.4	<0.27
Plutonium-238	0.030	0.0009	0.0068	0.0069	0.038
Plutonium-239+240	0.054	0.028	0.015	0.012	0.042
Plutonium-241	1.5	0.57	0.46	0.55	1.89
Americium-241	0.086	0.042	0.028	0.025	0.044
Curium-242	0.019	0.018	0.014	<0.0009	0.13
Curium-243+244	0.0052	0.0017	0.00098	0.0013	0.012

Applies to any period of 12 consecutive months.
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.2.5 Wylfa

Radioactive liquid discharges from Wylfa over the past five years are shown in Table 12 . Fission products are normally absent from Wylfa’s discharges, because it has no cooling ponds but has a dry storage system that uses carbon dioxide and air to cool irradiated fuel. Therefore, it has no specific limit on discharges of caesium-137.

‘Other activity’ is usually dominated by sulphur-35, unlike other sites where strontium-90 arising from the cooling ponds dominates (Section 3.2), unless electricity generation is low.

Table 12. Liquid radioactive discharges from Wylfa
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	8.6	6.1	8.5	3.3	6.2	15
Other activity^b	0.058	0.039	0.028	0.017	0.011	0.11
Other radionuclides	Annual discharge (GBq)
Sulphur-35	30	16	15	6.5	5.1
Calcium-45	< 0.2	0.28	0.24	<0.09	<0.13
Manganese-54	0.39	0.28	0.21	0.26	<0.1
Iron-55	1.5	2.3	0.41	0.48	<0.32
Cobalt-58	< 0.2	< 0.2	< 0.07	<0.07	<0.08
Iron-59	< 0.5	< 0.4	< 0.2	<0.3	<0.27
Cobalt-60	1.8	2.1	1.1	1.6	0.26
Zinc-65	< 0.3	< 0.2	< 0.1	<0.2	<0.24
Strontium-90	0.37	0.38	0.43	0.34	0.08
Yttrium-90	0.37	0.38	0.43	0.34	0.08
Zirconium-95	< 0.3	< 0.2	< 0.1	<0.2	<0.22
Niobium-95	< 0.3	< 0.2	<0.2	<0.2	<0.16
Ruthenium-106	< 0.7	< 0.3	< 0.3	<0.4	< 0.49
Rhodium-106	< 0.7	< 0.3	< 0.3	<0.4	<0.49
Silver-110m	< 0.2	< 0.1	< 0.1	<0.2	<0.13
Antimony-124	< 0.2	< 0.05	0.14	0.12	0.15
Antimony-125	< 0.3	< 0.2	< 0.2	<0.2	<0.18
Tellurium-125m	< 0.05	< 0.03	< 0.03	<0.04	<0.04
Caesium-134	2.0	1.2	0.530	0.31	0.19
Caesium-137	15	8.7	7.0	5.19	3.75
Cerium-144	< 0.4	< 0.3	< 0.2	<0.3	<0.42
Praseodymium-144	< 0.4	< 0.3	< 0.2	<0.3	<0.42
Europium-154	< 0.1	< 0.06	< 0.07	<0.08	<0.09
Europium-155	< 0.09	< 0.06	< 0.06	<0.07	<0.11
Plutonium-238	< 0.002	< 0.0014	< 0.0018	<0.0013	<0.0036
Plutonium-239+240	< 0.002	< 0.0014	< 0.0016	<0.0015	<0.0039
Plutonium-241	0.15	0.12	< 0.06	<0.08	0.16
Americium-241	0.0034	0.009	< 0.002	<0.001	<0.0006
Curium-242	< 0.004	0.004	< 0.003	<0.002	<0.0013
Curium-243+244	< 0.002	< 0.0009	< 0.0008	<0.0006	<0.0004

Applies to any period of 12 consecutive months.
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.3 Discharges from decommissioning sites

There is still potential for radioactive liquid discharges from decommissioning sites. Although fission products no longer arise from fuel in cooling ponds, they can arise from the decontamination of the pond itself and the processing and packaging of intermediate level Radioactive Waste. Therefore, it is still necessary to apply BPM. This may involve the operation of caesium removal plant to minimise discharges of fission products in the early stages of decommissioning.

All liquid discharges from decommissioning sites were within relevant quantitative limits in 2007.

Short-lived radionuclides are almost absent in discharges from decommissioning sites because of radioactive decay. Therefore, only those radionuclides that are likely to be detectable after the defuelling period are reported. Discharges of ‘other activity’ are usually dominated by strontium-90 (in equilibrium with yttrium-90). There are minor contributions from antimony-125, caesium-134 and plutonium-241. Caesium-134 is far less significant at decommissioning than at generating sites due to radioactive decay (half-life 2.1 years).

3.3.1 Berkeley

Liquid effluent is discharged to the River Severn through a dedicated discharge line. Liquid discharges no longer include effluent from Berkeley Centre, which is now delicensed. Radioactive liquid discharges over the past five years are shown in 13. Effluent transfers from Berkeley Centre prior to 2007 are shown in Table 14.

The significant reduction in caesium-137 tritium and other activity during 2007 is a result of the embargo on the use of the AETP (see section 2.3.1).

Table 13. Liquid radioactive discharges from Berkeley^a
Radionuclide	2003	2004	2005	2006		2007	Authorised limit (GBq)^b	Authorised limit (GBq) ^c
Subject to quantitative limits	Annual discharge (GBq)						Authorised Limits (GBq) 18/12/2002	Authorised Limits (GBq) 01/09/2006
Tritium	0.29	0.30	0.59	0.23		0.021	2000	1000
Caesium-137	0.19	0.14	6.7	0.27		0.049	200	200
Other activity^d	0.17	0.11	4.7	0.64		0.071	400	200
Other radionuclides^e	Annual discharge (GBq)
Other radionuclides^e				Q1-Q3	Q4
Iron-55	0.015	< 0.009	< 0.01	-	-	< 0.004
Cobalt-60	0.018	0.012	0.019	0.0084	0.0020	< 0.0005
Strontium-90	0.062	0.029	3.9	-	-	< 0.097
Yttrium-90	0.062	0.029	3.9	-	-	< 0.097
Antimony-125	< 0.009	< 0.006	< 0.02	<0.005	<0.003	< 0.0035
Caesium-134	< 0.007	< 0.005	< 0.004	<0.0005	<0.0009	< 0.0013
Europium-154	< 0.01	< 0.006	< 0.007	<0.004	<0.002	< 0.0007
Europium-155	< 0.007	< 0.006	< 0.008	<0.003	<0.002	< 0.0021
Plutonium-238	< 0.0005	< 0.0004	< 0.0004	-	-	< 0.0001
Plutonium-239+240	0.00079	< 0.0004	0.00085	-	-	0.0001
Plutonium-241	0.022	< 0.012	0.015	-	-	< 0.0021
Americium-241	0.0014	< 0.0002	0.0015	0.0022	0.0010	0.0003
Curium-242	< 0.0004	< 0.0003	< 0.0002	-	-	< 0.0001
Curium-243+244	< 0.0002	< 0.00008	< 0.00005	-	-	< 0.00002

Includes Berkeley Power Station (decommissioning) and Berkeley Centre.
Applies to any period of 12 consecutive months.
The limits were reduced on 1st September 2006 to come into line with the status of the site as a decommissioning site
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.
Only those radionuclides that might be detectable after defuelling (about 3 years after generation has ceased) are reported

Table 14.Disposal of liquid effluent from Berkeley Centre by transfer to Berkeley Power Station^a
Radionuclide	Disposal (GBq)		Authorised limit (GBq)^b
Radionuclide	2005	2006	Authorised limit (GBq)^b
Tritium	0.099	0.075	100
Caesium-137	0.15	0.14	10
Other activity ^c	0.038	0.056	10

Data unavailable prior to 2005.
Applies to any period of 12 consecutive months.
“Other activity” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.3.2 Bradwell

Radioactive liquid discharges over the past five years are shown in Table 15. There was a significant reduction in discharges of tritium, caesium-137 and other activity as a result of the completion of defuelling and removal of fuel from the site and the reduced use of the fuel ponds.

Table 15. Liquid radioactive discharges from Bradwell
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	0.13	0.18	0.32	0.25	0.028	7
Caesium-137	0.37	0.38	0.29	0.17	0.015	0.7
Other activity^b	0.28	0.27	0.35	0.26	0.025	0.7
Other radionuclides	Annual discharge (GBq)
Sulphur-35	2.3	1.3	0.16	<0.12	<0.013
Calcium-45	4.2	1.6	0.54	0.75	<0.035
Manganese-54	< 0.1	< 0.07	< 0.06	<0.06	<0.035
Iron-55	0.7	0.1	< 0.02	0.26	0.099
Cobalt-58	< 0.1	< 0.09	< 0.08	<0.07	<0.033
Iron-59	< 0.5	< 0.2	< 0.3	<0.21	<0.077
Cobalt-60	0.35	0.25	0.36	0.19	0.12
Zinc-65	< 0.3	< 0.2	< 0.2	<0.15	<0.11
Strontium-90	110	97.4	165	93.7	6.08
Yttrium-90	110	97.4	165	93.7	6.08
Zirconium-95	< 0.4	< 0.2	< 0.2	<0.16	<0.075
Niobium-95	< 0.4	< 0.2	< 0.2	<0.17	<0.079
Ruthenium-106	< 2	< 2	< 2	<0.89	<0.11
Rhodium-106	< 2	< 2	< 2	<0.89	<0.011
Silver-110m	< 0.2	< 0.2	< 0.09	<0.096	<0.056
Antimony-124	0.32	0.06	< 0.08	<0.11	0.033
Antimony-125	1.8	< 0.8	< 0.7	<0.5	0.23
Tellurium-125m	0.40	< 0.2	< 0.2	<0.11	0.052
Caesium-134	38	25	15.3	4.9	0.33
Cerium-144	< 2	< 2	< 1	<0.53	<0.2
Praseodymium-144	< 2	< 2	< 1	<0.53	<0.2
Europium-154	< 0.2	< 0.1	< 0.1	<0.09	<0.019
Europium-155	< 0.3	< 0.1	< 0.3	<0.2	<0.068
Plutonium-238	0.21	0.011	0.0085	0.01	0.0093
Plutonium-239+240	0.50	0.019	0.019	0.028	0.024
Plutonium-241	12	0.61	0.48	0.59	0.39
Americium-241	0.29	0.0062	< 0.0119	0.018	0.016
Curium-242	< 0.02	< 0.003	< 0.002	<0.0015	<0.0013
Curium-234+244	0.0067	0.0008	< 0.00064	<0.00047	<0.0008

Applies to any period of 12 consecutive months.
“Other activity”refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.3.3 Hinkley Point A

Discharges from Hinkley Point A over the past five years are shown in Table 16. Releases of tritium and caesium-137 decreased with time between 2003 and 2007, whilst discharges of ‘Other Radionuclides’ remained broadly similar. No QNLs were exceeded in 2007.

Table 16. Liquid radioactive discharges from Hinkley Point A
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Subject to quantitative limits	Annual discharge (TBq)
Tritium	0.54	0.42	0.38	0.28	0.33	1.8
Caesium-137	0.49	0.27	0.19	0.14	0.18	1
Other activity^b	0.13	0.080	0.16	0.13	0.14	0.7
Other radionuclides	Annual discharge (GBq)
Sulphur-35	< 0.11	< 0.1	< 0.06	<0.043	0.03
Calcium-45	< 0.14	0.54	0.29	0.32	0.7
Manganese-54	< 0.08	< 0.08	< 0.04	<0.03	<0.02
Iron-55	0.58	0.33	0.59	0.19	<0.1
Cobalt-58	< 0.13	< 0.08	< 0.05	<0.03	<0.03
Iron-59	< 0.42	< 0.2	< 0.1	<0.11	<0.2
Cobalt-60	0.43	0.33	0.42	0.18	0.1
Zinc-65	< 0.3	< 0.2	< 0.11	<0.07	<0.09
Strontium-90	75	60	98	96	93
Yttrium-90	75	60	98	96	93
Zirconium-95	< 0.33	< 0.2	< 0.2	<0.09	<0.09
Niobium-95	< 0.3	< 0.2	< 0.1	<0.08	<0.07
Ruthenium-106	< 1.3	< 1.4	< 0.6	<0.3	<1.0
Rhodium-106	<1.3	< 1.4	< 0.6	<0.3	<1.0
Silver-110m	< 0.12	< 0.13	< 0.05	<0.04	<0.048
Antimony-124	< 0.14	< 0.14	< 0.03	<0.05	<0.052
Antimony-125	3.2	5.5	1.6	0.45	0.78
Tellurium-125m	0.73	1.3	0.4	0.1	0.18
Caesium-134	33	9.9	5	2	1.5
Cerium-144	< 1.3	< 0.8	< 0.5	<0.3	<0.7
Praesodymium-144	< 1.3	< 0.8	< 0.5	<0.3	<0.68
Europium-154	0.72	0.14	0.64	0.18	<0.06
Europium-155	< 0.4	< 0.3	0.3	<0.12	<0.2
Plutonium-238	0.21	0.09	0.55	0.12	0.17
Plutonium-239+240	0.32	0.16	1.24	0.3	0.43
Plutonium-241	10	4.4	24	5	6.9
Americium-241	0.82	0.55	3.6	0.86	1.4
Curium-242	0.0089	0.0089	0.026	0.0058	<0.007
Curium-234+244	0.049	0.032	0.11	0.021	0.026

Applies to any period of 12 consecutive months.
“Other activity”refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.3.4 Hunterston A

Liquid effluent from Hunterston A is discharged to the Firth of Clyde via British Energy Hunterston B station’s cooling water outfall culvert. Discharges from Hunterston A over the past five years are shown in Table 17.

Table 17. Liquid radioactive discharges from Hunterston A via Hunterston B
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq) ^a
Subject to quantitative limits	Annual discharge (GBq)
Tritium	1.0	0.67	0.48	0.53	0.39	700
Plutonium-241	0.20	0.21	0.15	0.063	0.054	1000
Other β activity ^b,d	44	63	47	46	36.70	600
α^c,d	0.17	0.15	0.13	0.087	0.069	40
Other radionuclides	Annual discharge (GBq)
Caesium-137	19	23	16	-	-^e
Plutonium-238	-	-	-	-	-^e
Plutonium-239+240	-	-	-	-	-^e
Americium-241	-	-	-	-	-^e
Curium-243+244	-	-	-	-	-^e

Applies to any period of 12 consecutive months.
Defined in the certificate as “β emitting radionuclides taken together (excluding tritium and plutonium-241)”.
Defined in the certificate as “α emitting radionuclides taken together”.
“Other β activity” and “α” refer to specified analytical determinations. They do not reproduce precisely the contributions from individual radionuclides.
Quarterly specific activities are reported by NEXIA for these radionuclides for the Pond Delay Tank but not reported as an activity discharged.

3.3.5 Trawsfynydd

Effluent from the active effluent treatment plant is discharged through the dedicated culvert to Trawsfynydd Lake. This is a different situation to the other Magnox sites where discharges are made to the sea or an estuary. Consequently, a limit has been placed on discharges of strontium-90 only at Trawsfynydd, in addition to the limit on discharges of caesium-137, as this radionuclide is more likely to accumulate in aquatic organisms in the enclosed environment of a lake. In addition to discharges of active effluent, there is measurable radioactivity in surface and sub-surface water from the reactor area. This is intercepted and pumped to the lake via a diversion culvert.

Discharges from Trawsfynydd over the past five years are shown in Table 18. Since December 2002, the specific limit on discharges of strontium-90 has been subsidiary to that on discharges of ‘Other activity’, which is now comparable with the quantity limited in discharges from Magnox sites in England. Previously, ‘other activity’ was dominated by yttrium-90.

The specific activity of caesium 137 in the site’s main site drainage discharge was greater than the QNL for a period during the year but at all times it was far below the limit set by the Environment Agency in the site’s RSA 93 Authorisation.

Table 18. Liquid radioactive discharges from Trawsfynydd
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq) ^a
Subject to quantitative limits	Annual discharge (GBq)
Tritium	36	25	16	3.3	3.2	500
Caesium-137	1.8	2.0	1.2	1.7	1.1	30
Other activity including strontium -90 ^b	6.4	11	3.3	1.9	1.2	170
Strontium-90 ( by Cerenkov counting)	2.2	3.4	0.8	0.32	0.14	50
Other radionuclides ^c,d	Annual discharge (GBq)
Strontium-90 (by radiochemical analysis)	-	-	-	0.23	0.082
Iron-55	0.18	0.1	0.042	<0.033	<0.32
Cobalt-60	0.11	0.09	0.013	0.053	0.26
Yttrium-90	2.0	3.5	0.8	0.23	0.082
Antimony-125	< 0.06	< 0.07	< 0.04	<0.04	<0.18
Caesium-134	< 0.02	< 0.03	< 0.01	<0.01	0.19
Europium-154	< 0.02	< 0.06	< 0.01	<0.02	<0.091
Europium-155	< 0.03	< 0.03	< 0.03	<0.02	<0.11
Plutonium-238	0.0059	0.0039	0.0039	0.0021	<0.0036
Plutonium-239+240	0.016	0.011	0.0104	0.0045	<0.0039
Plutonium-241	0.37	0.23	0.20	0.089	0.16
Americium-241	0.062	0.042	0.029	0.016	<0.0006
Curium 242	< 0.005	< 0.0019	< 0.0008	0.0005	<0.0013
Curium-243+244	0.0022	< 0.0016	0.00059	0.0005	<0.0004

Applies to any period of 12 consecutive months.
“Other activity including strontium-90” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.
Excludes discharges from the sewage plant and diversion culvert.
Only those radionuclides that might be detectable after defuelling (about 3 years after generation has ceased) are reported.

3.4 Aerial discharges

3.4.1 Discharges from generating and defuelling sites

The carbon dioxide coolant in Magnox reactors becomes neutron-activated and contaminated with radioactivity as it passes through the reactor, so coolant releases contribute to aerial discharges of radioactivity from reactors. There is a continuous small release (leakage) of carbon dioxide from all pressurised operating Magnox reactors. The clean carbon dioxide from burst can (leaking fuel) detection system and/or carbon dioxide make up system, replaces this small release. Consequently, reactors with concrete pressure vessels need to make additional minor discharges daily to prevent over-pressurisation. (Leakage from reactors with steel pressure vessels, now shut down, was adequate to prevent this). More significant releases occur when the reactors are fully depressurised prior to routine maintenance. There are also small aerial discharges of radioactive particles from the filtered contaminated ventilation systems, in addition to small quantities from reactor coolant. The leaked radioactive carbon dioxide does not present a threat to the operators or the public.

The main radioactive gases discharged from the sites are argon-41, tritium, carbon-14 and sulphur-35. Argon-41 is an activation product of argon-40, which comprises about 1% of air. Argon-40 is also a trace impurity in the carbon dioxide supplied to cool the reactors, so argon-41 is present in discharges of coolant. Argon-41 has a half-life of only 1.8 hours, so discharges rapidly fall to zero through radioactive decay whenever the reactor comes off load. Consequently, argon-41 is not discharged from defuelling sites.

Tritium is generated by two processes in the reactor; irradiation of lithium impurities in the moderator and as a product of ternary fission from the fuel. Lithium impurities are the major source during the early generating life of the reactors, but become less important with time as they are burnt out of the moderator. Generation from ternary fission is directly proportional to the reactor power loading. Under normal operating conditions with the gas circuits very dry tritium accumulates on the reactor internal surfaces (it has a half-life of 12 years, so losses through radioactive decay in a generating reactor are not significant). However, tritium has a strong affinity for moisture, so if moisture enters the gas circuit, it displaces tritium from the reactor surfaces as tritiated water. This may be removed by installed dryers and discharged to the environment in the site's cooling water discharge, together with other liquid effluents. Alternatively, the tritiated water is discharged as a gas. Consequently, there is normally a peak in gaseous discharges whenever air is allowed into the circuit for maintenance following depressurisation of a reactor. Although this air is passed through dryers first, its moisture content is still higher than that of the carbon dioxide coolant.

Aerial discharges of carbon-14 derive mainly from the graphite moderator, where it accumulates with irradiation (the half-life is 5700 years, so losses through radioactive decay in a generating reactor are trivial). While the reactor is at power, oxidation of the graphite moderator causes release of carbon-14 to the carbon dioxide coolant, at a rate which depends on reactor gas chemistry. Therefore, discharges of carbon-14 increase gradually with time as the radionuclide accumulates in the moderator, although any trend is usually apparent only over several years and only then if it is not masked by long outages when discharges are very low.

Sulphur-35 in coolant gas arises through activation of chlorine and stable sulphur impurities in the graphite moderator and oils used in the gas circulators. Because of its short half life (87 days), it usually reaches equilibrium in the coolant while the reactor is at power, but deposits on to internal reactor surfaces when the reactor comes off load. It is driven off again when the reactor returns to power, resulting in a peak in aerial sulphur-35 discharges. As defuelling typically takes about three years, discharges of sulphur-35 cease before defuelling is complete.

Quantitative limits on the annual discharge of each of the above radionuclides apply at generating stations in England and Wales. Subsidiary limits have been placed on discharges of radionuclides from minor outlets. These have been set at 1% of the relevant site limits; exceptions are discussed under the relevant station heading. WALs apply to discharges of tritium, carbon-14 and sulphur-35.

Quantitative limits also apply to annual discharges of ‘β emitting radio-nuclides associated with particulate matter’ (β particulate), although such discharges are much smaller than discharges of the gaseous species. Individual radionuclides in these particulates are not determined routinely. However, assessments have been made previously of their radionuclide composition from which it is known that cobalt-60 is the dominant species. Calcium-45, iron-59, nickel-63, zinc-65, silver-110m, antimony-124, caesium-134, caesium-137 and plutonium-241 are also present.

All aerial discharges from generating power stations were within quantitative limits in 2007. Any QNLs or WALs that were exceeded are discussed in the relevant sections below .

3.4.1.1 Chapelcross

Discharges of tritium, sulphur-35 and argon-41 over the past five years are shown in Table 19. No quantitative limit on discharges of carbon-14 is specified in the current authorisation. Although the Chapelcross Processing Plant (CXPP) closed in 2005, this plant remains the dominant source for aerial tritium discharges.

Table 19. Airborne radioactive discharges from Chapelcross
Radionuclide	Annual discharge (TBq)					Authorised limit (TBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Tritium	410	594	300	121	85.1	5000
Sulphur-35	0.004	0.0008	0.000023	0.000041	0.000027	0.05
Carbon-14	0.15	0.036	0.00065	0.000095	0.000056	-
Argon-41	750	69	-	-	-	4500

Applies to any period of 12 consecutive months.

3.4.1.2 Dungeness A

Discharges of tritium, carbon-14, sulphur-35, argon-41 and β particulate over the past five years are shown in Table 20. Since December 2006 and the cessation of generation there will be little or no further discharges associated with neutron activation and therefore the discharges of carbon-14, sulphur-35 and argon-41 have significantly reduced.

The WALwas exceeded in January following cessation of generation and shutdown and blowdown of both reactors, with the agreement of the EA & NII. The week's disposal was 133 GBq against a WAL of 100 GBq.

Reactor 1 was shutdown and put on dry air purge 31st Jan 2007. Reactor 2 was shutdown and put on dry air purge 19th Jan 2007.

Table 20. Airborne radioactive discharges from Dungeness A
Radionuclide	Annual discharge (TBq)					Authorised limit (TBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Tritium	0.48	0.40	0.50	0.18	0.22	2.6
Carbon-14	3.4	3.1	1.91	1.93	0.24	5
Sulphur-35	0.036	0.038	0.036	0.047	0.0017	0.15
Argon-41	1100	1035	1023	1280	0	1700
β particulate ^b	<0.0003	0.00018	0.00018	0.0002	<0.0001	0.00055

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.1.3 Oldbury

Chemical impurities (principally carbon monoxide) are removed from the coolant at Oldbury by condensing the gas as it is bled through a liquefaction plant. The carbon dioxide coolant vaporises as the gas mixture is allowed to regain ambient temperature and is returned to the gas circuit. The impurities vaporise at different temperatures and are discharged to atmosphere.

Discharges of tritium, carbon-14, sulphur-35, argon-41 and β particulate over the past five years are shown in Table 21.

Table 21 Airborne radioactive discharges from Oldbury
Radionuclide	Annual discharge (TBq)					Authorised limit (TBq) ^a
	2003	2004	2005
	2003	2004	2005	2006	2007
Tritium	3.3	2.9	2.2	1.7	1.3	9
Carbon-14	1.9	1.5	1.15	0.89	0.32	4
Sulphur-35	0.17	0.11	0.077	0.041	0.013	0.45
Argon-41	76	38	25	20	5.2	500
β particulate ^b	0.000049	0.000037	0.000035	0.000014	0.000016	0.0001

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.1.4 Sizewell A

Discharges of tritium, carbon-14, sulphur-35, argon-41 and β particulate over the past five years are shown in Table 22. Since December 2006 and the cessation of generation there will be little or no further discharges associated with neutron activation and therefore the discharges of carbon-14, sulphur-35 and argon-41 have significantly reduced.

The WAL was triggered at the beginning of 2007 due to the double reactor shutdown and depressurisation as a result of the planned cessation of generation. As this was pre-planned a notification was made to the Environment Agency and Food Standards Agency prior to the Weekly Advisory Level being exceeded.

Table 22. Airborne radioactive discharges from Sizewell A
Radionuclide	Annual discharge (TBq)					Authorised limit (TBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq) ^a
Tritium	1.9	1.4	1.7	1.4	1.18	3.5
Carbon-14	1.3	1.1	1.2	1.5	0.11	2
Sulphur-35	0.18	0.12	0.16	0.14	0.015	0.35
Argon-41	2000	1400	1991	2130	0.0	3000
β particulate ^b	0.00021	0.00016	0.00022	0.00022	0.0000038	0.00085

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.1.5 Wylfa

Discharges of tritium, carbon-14, sulphur-35, argon-41 and β particulate from Wylfa over the past five years are shown in Table 23. Discharges were similar to those in recent years. The limits on discharges from minor routes at Wylfa are 2% of the relevant site limits, although a higher limit (8%) may be applied to discharges from the economiser penetration vent, providing this is justified in advance.

The Reactor 1 outage resulted in the WAL for tritium and carbon-14 being exceeded due to the reactor blowdown and purge.This is a routine event on entering an outage.

Table 23. Airborne radioactive discharges from Wylfa
Radionuclide	Annual discharge (TBq)					Authorised limit (TBq)^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (TBq)^a
Tritium	4.5	3.1	2.4	2.6	2.8	18
Carbon-14	1.4	1.3	1.3	1.3	1.0	2.3
Sulphur-35	0.18	0.19	0.18	0.16	0.13	0.45
Argon-41	41	34	20	15	14.3	100
β particulate ^b	0.000030	0.000035	0.000032	0.000036	0.00048	0.0007

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.2 Discharges from decommissioning sites

Aerial discharges from decommissioning sites are very much smaller than from generating stations. Discharges of short-lived radionuclides cease prior to decommissioning (Section 3.4.1). Discharges of carbon-14 from decommissioning sites are very small because significant exchange with the moderator requires the reactor to be both under pressure in carbon dioxide and at power. Discharges of tritium are also small because the diffusion rate from the reactor core is very low at ambient temperature. Despite this, tritium is the major contributor to aerial discharges from decommissioning reactors because they are open to moist ambient air. Particulate discharges vary, depending on the phasing of decommissioning operations.

All aerial discharges from decommissioning sites were within relevant quantitative limits and no QNLs were exceeded. There is no distinction between major and minor outlets at most decommissioning sites, so there are no subsidiary limits (Section 3.4.1). WALs have not been applied at decommissioning sites.

3.4.2.1 Berkeley Nuclear Licensed Site

Low levels of airborne radioactivity are discharged from the two reactor vessels via engineered control vents that manage reactor pressure, temperature and humidity. Low levels of radioactivity are also discharged from vent systems in the active effluent treatment plant, the caesium removal plant, the low level waste handling facility and the active waste vault retrieval building .

Aerial radioactive discharges from Berkeley Power Station over the past five years are shown in Table 24 and those from Berkeley Centre are shown in Table 25. Prior to 2003, a single set of limits applied to the Berkeley Site, with a subsidiary limit on discharges of “α and β particulate” from Berkeley Centre. The limits on discharges of “α and β particulate” have been replaced with limits on “β particulate”.

Table 24. Airborne radioactive discharges from Berkeley Nuclear Licensed Site^a
Radionuclide	Annual discharge (GBq)					Authorised limit (GBq)^b
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq)^b
Tritium^c	3.6	5.5	3.3	3.8	4.21	20
Carbon-14 ^c	0.21	0.21	0.91	0.17	0.25	5
β particulate ^d	0.00010	0.00015	0.00013	0.00012	0.0025	0.02

Shielded Area after partial delicensing is now included as part of Berkeley Nuclear Licensed Site, effective from Jan 2007 and is reported to EA as one licensed site.
These limits apply from 01/01/2007 prescribed in RSA 93 COA BA5660/BZ7836
Passive discharges via engineered control vents only (see Section 3.4.2.1).
“β particulate” and “α particulate” refer to specified analytical determinations. It does not reproduce precisely the contributions from individual radionuclides.

Berkeley Centre now consists of offices and laboratories that were formerly part of Berkeley Nuclear Licensed site but that were de-licensed at the end of 2006. There are therfore no airborne radioactive discharges that are required to be reported in this report. Table 25 is retained to provide historic data.

Table 25. Airborne radioactive discharges from Berkeley Centre
Radionuclide	Annual discharge (GBq)					Authorised limit (GBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq) ^a
Tritium	0.17	0.062	0.082	0.1	-	50
Carbon-14 ^b	0	0	0	0	-	1
β particulate^c	0.0003	0.00049	0.00039	0.00029	-	0.01

Applies to any period of 12 consecutive months from 18 December 2002 but does not apply after 31 December 2006..
Discharges are reported only when gaseous carbon-14 sources are disposed of.
“β particulate” and “α particulate” refer to specified analytical determinations. It does not reproduce precisely the contributions from individual radionuclides.

3.4.2.2 Bradwell

Discharges of tritium, carbon-14, sulphur-35, argon-41 and β particulate over the past five years from Bradwell are shown in Table 26. The discharges of tritium, carbon-14, and β particulate are similar to those of previous years.

Table 26. Airborne radioactive discharges from Bradwell
Radionuclide	Annual discharge (GBq)					Authorised limit (GBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq) ^a
Tritium	88	24	22	8.4	22.6	1500
Carbon-14	3.8	2.6	2.5	0.56	1.11	600
Sulphur-35	0.085	0.025	0.016	-	-	20
β particulate^b	0.020	0.018	0.014	0.0098	0.0041	0.6

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.2.3 Hinkley Point A

Discharges from Hinkley Point A over the past five years are shown in Table 27. Limits no longer apply to discharges of sulphur-35 or argon-41, as each can no longer be detected in discharges.

The noticeable increase in releases of gaseous tritium between 2004 and 2005 resulted from an increase in the scope of the discharge monitoring programme to cover selected minor discharge routes other than releases from the two Magnox reactors. More specifically, releases of tritium due to Fuel Cooling Pond water evaporation, that had previously been estimated by assessment, were revised upward when a programme of monthly measurements commenced in 2005.

Table 27. Airborne radioactive discharges from Hinkley Point A
Radionuclide	Annual discharge (GBq)					Authorised limit (GBq) ^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq) ^a
Tritium	66	62	154	121	103	1500
Carbon-14	2.6	1.5	0.76	0.69	0.71	600
Sulphur-35	-	-	-	-	-	-
β particulate^b	0.0030	0.0027	0.00076	0.00084	0.00044	0.15

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.2.4 Hunterston A

Airborne discharges are largely from the main active ventilation discharge routes. These serve both reactors’ fuel separating rooms, the cartridge cooling pond enclosure and the solid active waste building. The valve on the reactors’ discharge stack is normally closed; an anti-corrosion atmosphere is maintained via the occasional introduction of dry air to the vessels as required, discharges being made via the original stack through a high efficiency particulate air filter system.

Discharges from Hunterston A over the past five years are shown in Table 28. The values for 2006 are similar to previous years and have remained low. Purging of the reactors to maintain satisfactory anti-corrosion conditions was not required in 2006. The passive discharge of tritium and carbon-14 is now included in routine declarations to SEPA, and is included in Table 28. The routine extract ventilation of active areas was the primary source of site discharge activities.

Table 28. Airborne radioactive discharges from Hunterston A
Radionuclide	Annual Discharge (GBq)					Authorised limit (GBq)^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq)^a
Tritium^b	1.59	1.36	1.54	1.78	1.61	20
Carbon-14^b	0.19	0.13	0.11	0.16	0.18	2
β particulate ^c	0.00045	0.00029	0.00021	0.00028	0.00038	0.06

Applies to any period of 12 consecutive months.
Excludes passive exchange with the air prior to 2003 (see Section 3.4.2.4).
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.4.2.5 Trawsfynydd

The major airborne discharges are from vent systems in the reactor and radioactive Intermediate Level Waste (ILW) process plants. The various active area vent systems are monitored for particulate discharges. The reactor vessels breathe naturally to air through engineered vent lines. Vessel air is monitored for carbon-14 and tritium; several active ventilation systems are also monitored for tritium. Discharges from Trawsfynydd over the past five years are shown in Table 29.

Table 29. Airborne radioactive discharges from Trawsfynydd
Radionuclide	Annual Discharge (GBq)					Authorised limit (GBq)^a
Radionuclide	2003	2004	2005	2006	2007	Authorised limit (GBq)^a
Tritium	56	52	61	108	121	750
Carbon-14	1.4	1.2	3.2	3.0	2.7	10
β particulate ^b	0.00048	0.00033	0.00030	0.00027	0.00039	0.05

Applies to any period of 12 consecutive months.
“β particulate” refers to a specified analytical determination. It does not reproduce precisely the contributions from individual radionuclides.

3.5 Disposals of combustible waste

Dungeness A, Oldbury, Sizewell A and Wylfa all have authorisations to dispose of combustible solid waste by incineration on site. The authorisation in effect at Dungeness A, Oldbury and Wylfa also permit the disposal of waste oil (including solvents etc.); however the oil burner at Wylfa is now permanently out of service. Berkeley, Trawsfynydd and Wylfa are also authorised to dispose of waste oil, solvents and scintillant by transfer to the industrial incinerator near Hythe. Hinkley Point A disposes of both solid waste and oil to British Energy’s Hinkley Point B site for incineration. Bradwell is authorised to dispose of waste oil (including solvents and scintillant) by incineration on site. Sizewell A is authorised to dispose of the equivalent waste to British Energy’s Sizewell B site for incineration. Bradwell, Chapelcross, Hunterston A and Trawsfynydd all send their combustible solid waste to the LLWR where it is processed as normal LLW.

Disposals of combustible waste by incineration on site are shown in Table 30. Dungeness A also receives combustible waste from its neighbouring station, Dungeness B, owned by British Energy. These disposals are included in the figures in Table 30.

Table 30. Disposals of radioactive combustible waste by incineration on site (MBq) in 2007
Radionuclide		Site
Radionuclide		Bradwell ^a	Dungeness A ^b	Oldbury^c	Sizewell A^d	Wylfa
Tritium	Max. (monthly)	0.0	7.4	170	46.5	3594
	Limit (monthly)	800000	500	450	500	15000
	Annual	0.0	32.8	554	102	11414
Sulphur-35	Max. (monthly)	-	0.6	28.7	0.53	206
	Limit (monthly)	-	500	350	100	1000
	Annual	-	2.6	93.4	1.19	606
Chlorine-36	Max. (monthly)	-	-	-	-	26
	Limit (monthly)	-	-	-	-	500
	Annual	-	-	-	-	79
Iron-55	Max. (monthly)	-	16.3	306	11.5	778
	Limit (monthly)	-	500	600	200	1000
	Annual	-	73.2	984	24.8	2319
Other activity	Max. (monthly)	29.4	10.7	94	82.7	172
	Limit (monthly)	500	650	200	150	1000
	Annual	29.4	62.0	604	200	601

Bradwell is authorised to dispose of organic liquids (oil, solvents and scintillants) by incineration on site, but no disposals were made in 2007.
Solid waste and waste organic liquids.
Authorised to incinerate solid and organic organic liquids.
Although authorised to incinerate both solid waste and waste organic liquids, waste organic liquids are disposed of by transfer to Sizewell B operated by British Energy (Table 32)

Disposals of solid combustible waste (including oil) from Hinkley Point A by transfer to Hinkley Point B (British Energy) are shown in Table 31.

All disposals of combustible waste were within relevant quantitative limits.

Table 31. Disposals of radioactive combustible waste from Hinkley Point A by transfer to Other Authorised Locations (MBq) in 2007
Radionuclide	Disposal to Hinkley Point B		Disposal to Other Licensed Operator^a	Authorised Limit
Radionuclide	Solid	Organic liquids	Disposal to Other Licensed Operator^a	Authorised Limit
Tritium	0.0	0.0	0.92^b	N/A
Carbon-14	0.0	0.0	(see above)	N/A
Cobalt-60	0.0	0.0	0.0	N/A
Iodine-129	0.0	0.0	0.0	N/A
α	0.0	0.0	11.76	N/A
Other Activity	0.0	0.0	329	N/A
Volume m³	0.0	0.0	8.34	75

Transfered to the licensed operator of the incinerator at Hythe.
Tritium plus ¹⁴C.

Disposals of oil are shown in Table 32, either by incineration on site (where data are available to distinguish these disposals from disposals of solid waste) or by transfer to other premises. No disposals of oil took place from Berkeley or Bradwell in 2007.

Table 32. Disposals of radioactive waste organic liquids in 2007 (MBq)^a
Radionuclide		Site^b
Radionuclide		Berkeley^c	Dungeness	Oldbury	Sizewell A^d	Trawsfynydd	Wylfa
Tritium	Disposal	36.9	91.6	11.5	88.2	0	221
Tritium	Annual Limit	3000	500	450	300	300	800
Sulphur-35	Disposal	-	50.6	0.27	-	-	-
Sulphur-35	Annual Limit	-	500	350	-	-	-
Iron-55	Disposal	-	3.0	0.083	-	-	-
Iron-55	Annual Limit	-	500	-	-	-	-
Carbon-14	Disposal	0.1	-	-	-	-	-
Carbon-14	Annual Limit	100	-	-	-	-	-
Total β/γ	Disposal	119	12.7	0.031	19.6	0	36.2
Total β/γ	Annual Limit	6000	650	200	100	200	150
Total α	Disposal	3.21	-	-	-	-	-
Total α	Annual Limit	60	-	-	-	-	-
Other activity	Disposal	-	12.7	0.031	19.6	0	36.2
Other activity	Annual Limit	-	650	200	100	200	150
Volume (m³)	Disposal	27.25	52.1	1.94	13.8	0	10
Volume (m³)	Annual Limit	100	-	-	100	100	30

Waste oil, solvents and scintillants.
No disposals of organic liquids were made from Bradwell or Trawsfynydd in 2007; those from Hinkley Point A are shown in Table 31. Chapelcross has no authorisation for disposal of oil but has a transfer authorisation for disposal of scintillant. Hunterston A has no authorisation for disposal of organic liquid waste.
This is the total of solid and organic liquid waste transfered to the operator of the incinerator at Hythe.
Disposal to British Energy at Sizewell B for incineration.

3.6 Disposals to the Low Level Waste Repository

Where appropriate, the volume of the waste is reduced by compaction in the waste monitoring and compaction (WAMAC) plant at Sellafield. This waste consists of such items as gloves, protective clothing and cleaning materials. Where sites dispose of combustible low level waste by incineration on site, disposals to LLWR also include the ash from the incinerator.

Tables 33a and 33b give the volumes and activities consigned to the LLWR by Magnox sites. All disposals were within relevant annual limits.

Table 33 a. Disposals of radioactive low-level waste to LLWR in 2007 (MBq) ^a
Radionuclide		Site^b
Radionuclide		Berkeley	Bradwell	Dungeness A	Hinkley Point A	Sizewell A
Uranium	Disposal	89	0.0	2.13	6.59	6.3
Uranium	Limit	500	1000	1000	1000	1000
Radium-226 + Thorium-232	Disposal	0.0	0.0	0.0	0.0	0.0
Radium-226 + Thorium-232	Limit	100	100	100	100	100
Other α^c	Disposal	5497	70.0	149	2852	15999
Other α^c	Limit	15000	2000	2000	6000	26000
Carbon-14	Disposal	79.8	89.3	165	51.9	6295
Carbon-14	Limit	60000	500	300	3000	9000
Iodine-129	Disposal	9.84	0.0	0.0	0.0	0.1
Iodine-129	Limit	50	100	100	100	100
Tritium	Disposal	1827	79.8	2910	1800	24592
Tritium	Limit	350000	3000	9000	40000	115000
Cobalt-60	Disposal	1125	1363	399	343	4684
Cobalt-60	Limit	125000	26000	10000	30000	21000
Others ^d	Disposal	61268	13954	9976	83049	223518
Others ^d	Limit	1100000	315000	125000	1100000	380000
Volume (m³)	Disposal	197	306	141	168	132
Volume (m³)	Limit	1073	395	240	1500	390

All limits apply to a calendar year.
All sites are authorised to dispose of radioactive Low Level Waste (LLW) to LLWR.
α emitting radio-nuclides with half lives greater than three months excluding uranium, radium-226 and thorium-232.
Iron-55 and β emitting radionuclides with half lives greater than three months excluding carbon-14, iodine-129, tritium and cobalt-60.

Table 33 b. Disposals of radioactive low level waste to LLWR in 2007 (MBq) ^a
Radionuclide		Site^b
Radionuclide		Chapelcross	Hunterston A	Oldbury	Trawsfynydd	Wylfa
Uranium	Disposal	58.9	0.19	0.47	19.4	0.0
Uranium	Limit	-	1000	1000	1000	1000
Radium-226 + Thorium‑232	Disposal	0.0	0.0	0.0	-	0.0
Radium-226 + Thorium‑232	Limit	-	200	100	-	100
Other α ^c	Disposal	0.62	721	89.2	6630	3.67
Other α ^c	Limit	18000	10000	1200	44000	100
Carbon-14	Disposal	7.7	4.32	412	2689	51.8
Carbon-14	Limit	-	4000	3000	8400	500
Iodine-129	Disposal	0.0	0.0	0.0	-	0.0
Iodine-129	Limit	-	100	100	-	100
Tritium	Disposal	463	39.8	5084	58958	9601
Tritium	Limit	500000	25000	25000	63000	200000
Cobalt-60	Disposal	1470	23.2	145	4886	341
Cobalt-60	Limit	32000	75000	2000	51000	6000
Others ^d	Disposal	21630	11518	4828	159811	3188
Others ^d	Limit	70000	800000	100000	1400000	56000
Volume (m³)	Disposal	86.5	156	56.5	205.5	52.5
Volume (m³)	Limit	600	600	300	500	250

All limits apply to a calendar year.
All sites are authorised to dispose of radioactive Low Level Waste (LLW) to LLWR.
α emitting radionuclides with half lives greater than three months excluding uranium, radium-226 and thorium-232.
Iron-55 and β emitting radionuclides with half lives greater than three months excluding carbon-14, iodine-129, tritium and cobalt-60.

4.0 Monitoring of the environment for radioactivity

The EA and SEPA require the operator to carry out environmental monitoring locally to each Magnox site to demonstrate that the radiation doses to members of the public from discharges of Radioactive Waste are acceptable. The NII requires the assessment of doses to members of the public from direct radiation. The environmental monitoring programmes specified by the relevant Agency involve the sampling and analysis of a wide range of materials and the measurement of dose rates; for sites in England and Wales, these programmes are specified in the relevant CEAR document (Section 3.1).

Concentrations of radioactivity in the aquatic environment reflect liquid discharges, whereas radioactivity in the terrestrial environment generally reflects atmospheric discharges. Although some overlap may occur through sea to land transfer processes and on tidally inundated pastures, such overlap does not contribute significantly to public exposure around Magnox sites (Reference 27). The main pathways identified as relevant to calculating critical group doses attributable to radioactive discharges from Magnox sites are:

external gamma radiation from exposed inter-tidal sediments, particularly the fine silt and mud of estuaries and harbours,
internal exposure from the high rate consumption of seafood (particularly fish and shellfish),
external gamma radiation from airborne radioactivity,
internal exposure from the high rate consumption of local agricultural produce (particularly milk), and
inhalation of airborne radioactivity.

The first two pathways relate to liquid discharges, the remainder to aerial discharges. The habits and consumption rates relating to each pathway are kept under regular review (Reference 27). Doses from direct radiation, as distinct from discharges, are discussed separately.

4.1 Aquatic pathways

Seafood such as fish, crustacea and molluscs are monitored in the vicinity of coastal sites. Environmental indicators such as seaweed and sediment are also monitored. Samples of seafood and indicators are collected every calendar quarter, depending on local availability. Gamma dose rates are measured quarterly over beaches and other coastal areas frequented by members of the public. The environmental monitoring programme carried out by Oldbury also covers the nearby decommissioning site, Berkeley, although each site has its own specific Statutory Environmental Monitoring Programme from 2003. Similarly, the programmes for Dungeness A and Hunterston A have been assimilated into those for British Energy's Dungeness B and Hunterston B Power Stations.

Trawsfynydd discharges into an inland lake, where the radioactivity is not dispersed as readily as would be discharges to sea. Accordingly, a detailed monitoring programme of the lake continues despite the reduction in discharges. Three species of freshwater fish are monitored: rainbow trout, indigenous brown trout and perch although perch is no longer consumed by the public and is no loger included in dose calculations. The rainbow trout are replenished regularly with farmed trout to provide stocks for local anglers. Gamma dose rates are measured over lakeside beaches occupied by the public. Environmental indicators such as lake water and sediment are also monitored. All monitoring is carried out on a calendar quarter basis.

Trends in concentrations of radioactivity discharged by Magnox sites are not usually discernible in the environment because of the dominance of radioactivity from other sources. The situation is different at Trawsfynydd because, other than background fallout, the site’s discharges are the only significant source of man-made radioactivity in the lake (Section 3.3.3).

The concentrations of radioactivity in the edible parts of fish, crustacea and molluscs caught near coastal sites are summarised in Table 34 (a-h). Even though strontium-90 is a major component of ‘Other Radionuclides’ in liquid effluent at many of the sites, calculations have shown that it would be present at very low concentration in seafood and therefore not contribute significantly to internal dose. Therefore, as the analysis is time consuming and expensive it has not been specified in sites' respective CEAR. The exception is Chapelcross where the analysis is required by SEPA.

Americium-241 in the edible parts of fish, crustacea and molluscs is analysed by gamma spectrometry at the sites but produces unrealistically high values; therefore, the dose assessment is calculated using the average of the last five RIFE reports where the measurements are made using alpha spectrometry. Both site and RIFE data are presented in Table 34 (a-h).

The results of analyses of indicators collected near coastal sites are summarised in Tables 35 (seaweed) and 36 (sediments). From 2003 the EA has required sites in England and Wales to measure potassium-40 in sediments by gamma-ray spectrometry and report the result as an indicator of grain size (i.e. sediment type). MAFF (DEFRA) (Reference 28) has reported a range of 200 to 400 Bq kg^-1 (dry weight) in sand and a range greater than 700 Bq kg^-1 (dry weight) in mud. Measurements between 400 and 700 Bq kg^-1 are considered to be indicative of silt, whereas any below 200 Bq kg^-1 are indicative of shingle. These ranges have been applied in Table 36. Environmental data for Berkeley and Oldbury are usually combined; but for sediment samples, the CEARs for each site specify where samples should be taken. Accordingly, Berkeley is presented separately, as its sediment-sampling locations are a sub-set of those for Oldbury.

Gamma dose rates over inter-tidal sediments (Table 37) were similar to those in 2006. Berkeley is presented separately to Oldbury as for Table 36. From 2003, the EA has also required sites in England and Wales to carry out monitoring of the beach strandline for particles of elevated radioactivity and to carry out an annual survey of local fishing equipment to monitor contact dose rates to local fishermen. Surveys in 2007 revealed nothing above background for fishing equipment but there was one positive result for strandline monitoring at Sizewell A in the fourth quarter where 0.69 - 1.00 cps was measured compared to a background of 0.56 - 1.13 cps. This is not considered significant as it was so close to background.

Results of analyses of radioactivity in rainbow trout, brown trout and perch, and water from Trawsfynydd Lake are summarised in Table 38. Although perch was analysed it is no longer considered as a species that is consumed, therefore concentrations of radionuclides measured are not used in the estimation of the critical group (adult) doses to consumers of fish from Trawsfynydd Lake. Concentrations of radionuclides are generally higher in the indigenous species than in the farmed rainbow trout, which are usually caught shortly after being transferred to the lake.

Results of sediment and moss analyses are shown in Table 39. These include sediment cores from the lake and lake edge to assess if there has been any change in the deposition rates of radionuclides from the lake. Concentrations were similar to those in 2006.

Measurements of environmental gamma dose rates around the lake edge are summarised in Table 40. They include background contributions and are similar to those in 2006.

Table 34 (a). Radioactivity in sea foods in the vicinity of Bradwell in 2007^a
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁴⁰K	⁶⁰ Co	⁶⁵Zn	¹³⁴Cs	¹³⁷ Cs	^110mAg	²⁴¹Am	Gross β	²⁴¹Am inferred ^b
Fish	111	<0.72	<1.5	<0.64	<0.95	<0.62	<1.53	498	<0.15
Crustacea	-	-	-	-	-	-	-	-	<0.13
Native oyster	73	<0.22	<0.55	<0.22	<0.21	<0.21	<0.46	463	<0.16
Pacific oyster	73	<0.23	<0.58	<0.24	<0.18	<0.22	<0.57	462
Mussels	-	-	-	-	-	-	-	-
Winkles	-	-	-	-	-	-	-	-

There were no samples of crab, lobster mussels or winkles.
Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(b). Radioactivity in sea foods in the vicinity of Chapelcross in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁶⁰ Co	¹³⁴Cs	¹³⁷ Cs	²⁴¹Am	^110mAg	⁶⁵Zn	⁹⁰Sr	⁹⁹Tc	²⁴¹Am inferred^a
Seatrout	<0.1	<0.1	0.45	<0.1	<0.1	<0.1	<0.1	<0.5	<0.14
Flounder	<0.1	<0.1	12.1	<0.1	<0.1	<0.1	<0.1	<0.5	<0.14
Crustacea	-	-	-	-	-	-	-	-	0.034
Mollusc	--	-	-	-	-	-	-	-	8.1

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(c). Radioactivity in sea foods in the vicinity of Dungeness A in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁴⁰K	⁶⁰ Co	⁹⁵Nb	⁹⁵Zr	¹⁰⁶Ru	¹²⁵Sb	¹³¹I	¹³⁴Cs	¹³⁷ Cs	¹⁴⁴Ce	¹⁵⁴Eu	¹⁵⁵Eu	Gross β	²⁴¹Am inferred^a
Cod	221	<0.25	<0.23	<0.43	<2.35	<0.68	<0.25	<0.28	<0.5	<1.63	<0.48	<1.03	150	<0.13
Plaice	222	<0.25	<0.23	<0.45	<2.2	<0.6	<0.23	<0.28	<0.38	<1.78	<0.48	<1.0	179	<0.13
Shrimp	325	<0.4	<0.43	<0.73	<4.1	<1.27	<0.37	<0.53	<0.77	<3.3	<1.0	<1.87	124	<0.18
Crab	181	<0.27	<0.2	<0.27	<1.67	<0.67	<0.2	<0.27	<0.5	<1.67	<0.6	<1.03	433	<0.18
Cockle	-	-	-	-	-	-	-	-	-	-	-	-	-	<0.031
Mussel	151	<0.37	<0.23	<0.37	<1.8	<0.67	<0.23	<0.3	<0.37	<2.13	<0.6	<1.23	45.5
Scallops	178	<0.14	<0.22	<0.21	<1.99	<0.53	<0.17	<0.26	<0.29	<1.92	<0.49	<0.89	110
Whelk	175	<0.2	<0.23	<0.47	<2.37	<0.73	<0.23	<0.3	<0.43	<1.7	<0.5	<1.0	92.7

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(d). Radioactivity in sea foods in the vicinity of Hinkley Point A in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁴⁰ K	⁶⁰ Co	⁹⁵Nb	⁹⁵Zr	¹⁰⁶Ru	¹²⁵Sb	¹⁴⁴Ce	¹³⁴Cs	¹³⁷ Cs	¹⁵⁴Eu	¹⁵⁵Eu	²⁴¹ Am	^{Gross β}	²⁴¹Am inferred^a
Fish (free swimmers)	102	<0.3	<0.3	<0.4	<1.9	<0.6	<1.9	<0.3	0.6	<0.4	<0.8	<1.9	99.3	<0.08
Fish (Bottom Feeders)	100	<0.4	<0.5	<0.7	<2.8	<1	<2.2	<0.4	0.9	<0.6	<0.9	<0.5	94.5	<0.08
Shrimp	72.6	<0.3	<0.4	<0.6	<2.5	<0.8	<2.1	<0.4	0.8	<0.7	<0.9	<1.4	58.3	0.00087
Molluscs	-	-	-	-	-	-	-	-	-	-	-	-	-	<0.13

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(e). Radioactivity in sea foods in the vicinity of Hunterston A in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1)
Food type	¹³⁷Cs (wet)	¹³⁷ Cs (dry ash)	Gross β (wet)	Gross β (dry ash)	⁶⁰Co (dry ash)	⁶⁰Co(wet)	²⁴¹Am inferred^a
Cod	1.5	155	88.5	8710	-	-	<0.16
Flat fish	1	67.5	103	6340	-	-
Fish	2	1.18	120	9110	<7	<1
Lobster	0.5	32	88.5	3750	-	-	<0.13
Winkles	1	9	200	2520	-	-	<0.14

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(f). Radioactivity in sea foods in the vicinity of Oldbury and Berkeley in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁶⁰ Co	¹³⁴Cs	¹³⁷ Cs	¹⁴⁴Ce	¹⁵⁴Eu	¹⁵⁵Eu	¹³¹I	⁹⁵Nb	¹²⁵Sb	⁹⁵ Zr	⁴⁰ K	Gross β	²⁴¹Am inferred^a
Elver	<0.1	<0.1	<0.1	<0.4	<0.1	<0.3	<0.1	<0.1	<0.3	<0.2	42.0	43.0	<0.17
Mullet	<0.35	<0.25	0.75	<0.85	<0.25	<0.5	<0.15	<0.2	<0.65	<0.3	113	126
Severn Salmon	<0.35	<0.3	<0.4	<1.1	<0.3	<0.7	<0.3	<0.25	<0.85	<0.55	178	176
Crustacea	-	-	-	-	-	-	-	-	-	-	-	-	0.0016
Mollusc	-	-	-	-	-	-	-	-	-	-	-	-	-

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34(g). Radioactivity in sea foods in the vicinity of Sizewell A in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	⁶⁰ Co	⁹⁵Nb	⁹⁵ Zr	¹⁰⁶Ru	¹²⁵Sb	¹³¹I	¹³⁴Cs	¹³⁷ Cs	¹⁴⁴Ce	¹⁵⁴Eu	¹⁵⁵Eu	Gross β	²⁴¹Am inferred^a
Cod	<0.28	<0.24	<0.32	<1.64	<0.48	<0.2	<0.28	<0.4	<0.9	<0.32	<0.52	105	<0.1
Dab	<0.4	<0.2	<0.5	<2.0	<0.8	<0.3	<0.4	<0.3	<1.3	<0.4	<0.9	109
Herring	<0.3	<0.25	<0.4	<1.2	<0.5	<0.25	<0.25	<0.3	<0.7	<0.3	<0.55	115
Sea Bass	<0.36	<0.3	<0.43	<2.14	<0.54	<0.26	<0.34	<0.39	<0.84	<0.27	<0.4	90.3
Skate	<0.2	<0.1	<0.3	<1.5	<0.4	<0.1	<0.2	<0.2	<0.3	<0.3	<0.1	74.0
Sole	<0.28	<0.2	<0.36	<1.8	<0.48	<0.18	<0.28	<0.28	<0.84	<0.2	<0.28	93.6
Sprat	<0.3	<0.2	<0.3	<1.4	<0.3	<0.2	<0.2	<0.2	<0.6	<0.2	<0.2	30.0
Crab	<0.35	<0.33	<0.3	<2	<0.63	<0.17	<0.33	<0.3	<1.1	<0.33	<0.67	52	0.0009
Lobster	<0.2	<0.2	<0.4	<1.4	<0.5	<0.2	<0.3	<0.3	<0.75	<0.3	<0.45	66.5	0.0009
Oyster	<0.35	<0.3	<0.48	<2.18	<0.68	<0.28	<0.3	<0.3	<1.05	<0.28	<0.48	50.5	<0.12

Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 34 (h). Radioactivity in sea foods in the vicinity of Wylfa in 2007
Food type	Measured mean radionuclide concentration (Bq kg^-1 wet weight)
Food type	¹³⁷ Cs	⁴⁰K	⁶⁰Co	^{Gross β}	²⁴¹Am inferred^b
Fish	2.7	112	1.2	73.2	<0.18
Crab	0.5	117	<0.6	83.6	<0.13
Lobster	0.6	120	<0.6	73.5	<0.13
Mollusc	0.7	113	<0.6	80.2	0.2

< MDA (less than Minimum Detectable Activity).
Results inferred from last five RIFE reports. This value is used in the dose assessment.

Table 35. Radioactivity in seaweed in the vicinity of Magnox sites in 2007
Site^a	Species	Mean radionuclide concentration (Bq kg^-1 wet weight)
Site^a	Species	⁴⁰K	⁶⁰Co	⁶⁵Zn	⁹⁵Zr	⁹⁵Nb	⁹⁹Tc	¹⁰⁶Ru	^110mAg	¹²⁵Sb	¹³¹I	¹³⁴Cs	¹³⁷Cs	²⁴¹Am	¹⁴⁴Ce	¹⁵⁴Eu	¹⁵⁵Eu	Gross β
Berkeley	Fucus vesiculosus	165	<0.22	-	<0.37	<0.25	-	-	-	<0.6	<0.25	<0.25	<0.5		<0.75	<0.22	<0.55	146
Bradwell	Unspecified	183	<0.41	<1.1	-	-	-	-	<0.41	-	-	<0.41	<0.58	<0.95	-	-	-	201
Chapelcross	Unspecified	-	0.5	-	-	-	988	<0.9	-	0.6	-	<0.1	6.1	2.4	<0.4	-	-	219
Hinkley Point A	Unspecified	204	<0.2	-	<0.3	<0.2	-	<1.4	-	<0.4	-	<0.2	<0.8	<0.8	<0.8	<0.5	<0.85	186
Hunterston A	Unspecified	-	<0.001	-	-	-	-	-	-	-	-	-	<0.018	-	-	-	-	0.12
Oldbury	Unspecified	142	<0.39	-	<0.33	<0.2	-	-	-	<0.47	<2.03	<0.23	<0.57	-	<0.76	<0.22	<0.47	134
Wylfa	Fucus vesiculosus	279	<0.6	-	<2.1	<2.1	-	<2.1	<2.1	<2.1	<0.6	<0.6	0.8	-	<2.1	<2.1	<2.1	184
	Porphyra	188	<0.6	-	<2.1	<2.1	-	<2.1	<2.1	<2.1	<0.6	<0.6	1.0	-	<2.1	<2.1	<2.1	105
	Unspecified	287	1.1	-	<2.1	<2.1	-	<2.1	<2.1	<2.1	<0.6	<0.6	0.9	-	<2.1	<2.1	<2.1	238

Sampling of seaweed is not required at Dungeness A or Sizewell A

Table 36. Radioactivity in sediments in the vicinity of Magnox sites in 2007
Site^a	Mean radionuclide concentration (Bq kg^-1 dry weight)
Site^a	⁴⁰K	⁵⁸ Co	⁶⁰Co	⁶⁵Zn	⁹⁰Sr	⁹⁵Zr	⁹⁵Nb	¹⁰⁶Ru	^110mAg	¹²⁵ Sb	¹³¹ I	¹⁴⁴Ce	¹³⁴Cs	¹³⁷Cs	²⁴¹Am	¹⁵⁴Eu	¹⁵⁵Eu	Pu α	Gross β
Berkeley	493	-	<1.2	-	<0.42	<2.2	<0.88	-	-	<2.4	<1.0	<4.8	<1.2	21.5	-	<1.5	<2.8	-	632
Bradwell	662	-	<1.7	<4.5	<0.63	-	-		<2.1	-	-	-	<1.7	<25	<4.3	-	<5	-	1022
Chapelcross	-	-	<1.6	-	-	<1.0	<1.0	<6.0	-	<2.8	-	-	<1.0	66.0	148	-	-	82.0	701
Dungeness A	521	-	<0.92	-	<0.43	<1.9	<1.1	<8.9	-	<3.2	<1.4	<8.7	<1.4	<1.7	-	<2.3	<6.2	-	400
Hinkley Point A	648	-	<1.1	-	<0.78	<2	<0.32	<9.1	-	<2.8	-	<7.2	<1.2	23.4	<5.2	<2.1	<3.6	-	753
Oldbury	538	-	<1.4	-	<1.1	<2.1	<1.1	-	-	<2.9	<1.1	<5.2	<1.3	23.0	-	<1.4	<3.2	-	718
Sizewell A	238	-	<0.85	-	0.55	<1.3	<0.71	<5.9	-	<1.7	<0.78	<3.3	<1	<2.3	<2.4	<0.92	<2	-	220
Wylfa	477	-	<0.6	-	-	<2.1	<2.1	<2.1	<2.1	<2.1	<0.6	<2.1	<0.6	52.0	10.5	<2.1	<2.1	-	610

Sediments are not sampled at Hunterston A.

Table 37. Net gamma dose rates in the vicinity of Magnox sites associated with marine discharges in 2007
Site	Sediment type	Mean dose rate (µGy h^-1) (Corrected for background and cosmic radiation)
Berkeley	Silt	0.034
Bradwell	Mud/silt	0.024
Chapelcross	Pipeline^a	0.17
	Over Mud - Stake net fishermen	0.009
	Salt marsh - Wild fowlers	0.015
Dungeness A^b	Mud/silt/sand/shingle	0.0047
Hinkley Point A	Mud/silt/sand	0.039
Hunterston A ^c	Sand	0.027
Oldbury	Shingle/silt/sand	0.037
Sizewell A	Sand	0.0062
Trawsfynydd ^d	Lake edge	0.061
Wylfa	Silt/sand	0.037

Gamma dose rate in air, measured 2 m from the above ground sections of the discharge pipeline.
Average background and cosmic contribution of 0.047 µGy h^-1 subtracted from gross average.
Average background and cosmic contribution of 0.06 µGy h^-1 subtracted from gross average.
Trawsfynydd data refers to lake edge samples.

Table 38. Radioactivity in fish^a and water from Trawsfynydd Lake in 2007
Radionuclide	Mean radionuclide concentration^b Fish (Bq kg^-1 wet weight for fish, Bq m^-3 for water)
Radionuclide	Perch	Brown trout	Rainbow trout	Hot lagoon water	Cold lagoon water
⁶⁰Co	< 0.39	< 0.37	< 0.58	-	-
⁹⁰S	1.21 ± 0.40	< 0.39	< 0.37	-	-
⁹⁵Nb	< 120	< 54	< 93	-	-
⁹⁵Zr	< 14	< 8.1	< 15	-	-
¹⁰⁶Ru	< 7.8	< 5.7	< 9.3	-	-
¹²⁵Sb	< 1.6	< 1.0	< 1.7	-	-
¹³⁴Cs	< 0.55	< 0.52	< 0.84	<4	<4
¹³⁷Cs	129	34.2	< 0.60	20	16
¹⁴⁴Ce	< 5.0	< 2.9	< 5.8	-	-
¹⁵⁴Eu	< 1.1	< 1.1	< 1.7	-	-
¹⁵⁵Eu	< 1.7	< 0.94	< 1.9	-	-
²³⁸Pu	< 0.0016	< 0.0031	< 0.0026	-	-
^{239 + 240}Pu	< 0.0031	< 0.0058	< 0.0069	-	-
²⁴¹Am	< 0.0037	< 0.0026	< 0.0053	-	-
α particulate	-	-	-	2	1
β particulate	-	-	-	65	63

Edible parts only
Mean values include measurements that are quoted as less than values. Therefore Table values are pessimistic.

Table 39. Radioactivity in sediment and moss from Trawsfynydd Lake in 2007
Location	Sample	Mean radionuclide concentrations (Bq kg^-1 dry weight for sediment, Bq kg^-1 wet weight for moss)
Location	Sample	⁴⁰K	⁶⁰Co	⁹⁰Sr	⁹⁵Nb	⁹⁵ Zr	¹⁰⁶ Ru	¹²⁵Sb	¹³⁴Cs	¹³⁷Cs	¹⁴⁴Ce	¹⁵⁴Eu	¹⁵⁵Eu	²³⁸ Pu	^239-240 Pu	²⁴¹Am
Lake bed sediment	Core 0-3 cm	961	<5.4	12.8	<270	<47	<42	<11	<3	1570	<23	<6.3	<6.4	7.16	20.5	39.1
Lake bed sediment	Core 3-21cm	759	13.1	48.1	<260	<47	<48	<15	<2.9	4000	<29	<12	<7.8	19.4	83.4	170
Peat	Gram samples	555	18.7	52.7	<110	<21	<23	<34	5.37	2440	<17	13.4	<4.8	20.3	55.1	104
Fish farm	Core 0-3 cm	328	< 3.0	48.1	< 340	< 64	< 54	< 11	< 4.2	746	< 33	< 7.7	< 12	3.35	9.82	21.3
Fish farm	Core 3-21 cm	393	< 0.71	34.4	< 73	< 14	< 12	< 3.5	< 1.0	456	< 8.8	< 1.9	< 2.6	0.423	1.56	2.76
Bailey bridge	Core 0-3 cm	175	< 2.5	82.5	< 250	< 45	< 41	< 10.3	< 3.2	1120	< 22	< 6.6	< 5.6	8.10	29.6	65.7
Bailey bridge	Core 3-21 cm	215	3.61	93.6	< 130	< 23	< 21	< 6.6	< 1.5	1160	< 15	5.68	< 4.3	5.98	15.5	62.7
Footbridge	Core 0-3 cm	712	< 2.2	7.41	< 250	< 44	< 32	< 8.1	< 3.1	602	< 19	< 6.0	< 5.6	0.460	2.86	3.96
Footbridge	Core 3-14 cm	593	< 2.0	16.1	< 98	< 19	< 19	< 5.2	< 1.2	951	< 14	< 2.5	< 4.9	1.37	5.90	10.4
Cae Adda	Core 0-3 cm	425	<1.1	5.22	< 130	< 24	< 19	< 4.3	< 1.6	323	< 13	< 3.1	< 4.2	0.294	1.17	2.21
Cae Adda	Core 3-21 cm	337	< 0.59	6.66	< 69	< 14	< 10	< 2.3	< 0.84	122	< 7.5	< 1.8	< 2.6	0.0554	0.209	0.433
Gwylan Stream	Moss (Fontinalis)	113	<1	-	-	-	-	-	<1	45	-	-	-	-	-	-
Afon Prysor	Moss (Fontinalis)	70	<1	-	-	-	-	-	<1	4	-	-	-	-	-	-

Table 40. Gamma dose rates around Trawsfynydd Lake in 2007
Location	Substrate	Mean dose rate (µGy h^-1)^a
Fish farm	Tarmac	0.053
Bailey bridge	Grass/rock	0.068
Footbridge	Grass/rock	0.065
Cae Adda	Grass/rock	0.057

Less cosmic radiation.

4.2 Airborne and terrestrial pathways

In the terrestrial environment, the primary pathway for radioactivity into food is via milk; hence, grass and milk are monitored at local farms every calendar quarter. Grass is taken from a location near to the site and the four nearest farms. Milk is collected from farms selected to represent the area around the site, preferably with four farms in an inner zone (1-5 km) and another four in an outer zone (5-10 km). Control samples may also be selected from farms at a greater distance. Where no farms are available in the inner zone, a larger number of farms in the outer zone are monitored. Results of the analyses on grass are used as an indicator for radioactivity in vegetables for calculating radiation doses to the public. The exception is Chapelcross where vegetables are grown locally for environmental monitoring.

Since generation ceased at Berkeley, Hinkley Point A, Hunterston A, Bradwell and Trawsfynydd, aerial discharges have fallen by over an order of magnitude, so terrestrial environmental monitoring specific to the decommissioning sites has been greatly reduced, or assimilated into monitoring programmes for nearby operating stations. Monitoring of the milk from farms in the vicinity of Trawsfynydd has ceased altogether, although samples of grass are still analysed for carbon-14. Concentrations of iodine-131 (half life ~8 days) are significant only for generating stations. Concentrations of sulphur-35 are significant only for generating stations and stations in their first year of defuelling. Discharges from Magnox sites will not contribute to environmental concentrations of these radionuclides after this time, as they will have been lost through radioactive decay.

Results for monitoring of grass (vegetables at Chapelcross) are shown in Table 41. Results from the sampling location nearest to the site are shown, in addition to bulked samples from the farms that also provide milk samples. Generally, levels of radioactivity are elevated near to the site. Results for monitoring in milk are given in Table 42. Results were very similar to those reported for 2006. Iodine-131 was below the limit of detection in milk and vegetation around generating stations. Strontium-90 levels were similar to those of recent years. Carbon-14 levels in samples from farms did not differ significantly from the natural background level of 240 Bq kg^-1 carbon. Tritium levels in milk were similar to those in recent years. Tritium concentrations in green vegetables were lower than in 2006 reflecting the decrease in tritium discharges in 2007.

Table 41. Radioactivity in herbage in the vicinity of Magnox sites in 2007
Site	Location	Mean radionuclide concentration (Bq kg^-1 wet weight)
Site	Location	³ H	⁷ Be	¹⁴C^b	³⁵S	⁴⁰ K	⁶⁰Co	⁶⁵ Zn	⁹⁰Sr	⁹⁵Nb	⁹⁵ Zr	¹⁰⁶ Ru	^110m Ag	¹²⁵ Sb	¹³¹I	¹³⁴Cs	¹³⁷Cs	¹⁴⁴ Ce	¹⁵⁴ Eu	¹⁵⁵ Eu	²⁴¹ Am
Berkeley	Nearest site	-	79.5	219	-	160	<0.52	-	-	<0.6	<1.1	-	-	<1.4	<0.45	<0.62	<0.77	<2.5	<0.75	<1.62	-
Bradwell	Nearest site	-	-	256	-	244	<0.78	<2.02	-	-	-	-	<0.71	-	-	<0.82	<0.75	-	-	-	<3.2
Bradwell	Outer farms	-	-	246	-	232	<0.65	<1.61	-	-	-	-	<0.6	-	-	<0.66	<0.63	-	-	-	<3.1
Chapelcross^a	Samples taken 1 Km from site	36.0	-	240	<1.9	-	<0.1	-	0.5	-	-	-	-	-	-	<0.1	<0.1	-	-	-	-
Dungeness A	Farms	-	-	-	<4.5	-	<0.11	-	-	<0.17	<0.22	<1.2	-	<0.41	<0.16	<0.17	<0.14	<13.7	<4.6	<7.1	-
Hinkley Point A	Nearest site	-	102	-	-	308	<0.28	-	-	<0.31	<0.53	<2.8	-	<0.66	-	<0.32	<0.35	<2	<0.53	<0.87	-
Hinkley Point A	Inner farms	-	79.3	-	-	298	<0.23	-	-	<0.27	<0.46	<2.2	-	<0.69	-	<0.27	<0.32	<1.8	<0.52	<0.91	-
Hunterston A ^c	Inner milk farms	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Hunterston A ^c	Outer milk farms	-	-	-	-		-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Oldbury	Nearest site	-	173	272	<2.5	187	<0.75	-	-	<0.65	<0.77	-	-	<1.3	<0.52	<0.7	<0.87	<2.8	<0.67	<1.8	-
Oldbury	Inner farms	-	82.8	255	<2	200	<0.68	-	-	<0.66	<0.97	-	-	<1.5	<0.57	<0.7	<0.82	<2.9	<0.77	<1.6	-
Sizewell A	Nearest site	-	-	424	<2.2	-	<0.55	-	-	<0.48	<0.75	<3.3	-	<0.93	<0.6	<0.6	<0.58	<3.5	<1.0	<1.9	-
Sizewell A	Inner farms	-	-	322	<7.3	-	<0.59	-	-	<0.41	<0.81	<3.8	-	<1.1	<0.55	<0.54	<0.51	<2.6	<0.87	<1.74	-
Trawsfynydd	Nearest location	-	-	238	-	-	< 1	-	-	-	-	-	-	-	-	<1	< 1	-	-	-	-
Trawsfynydd	Bulk farms	-	-	166	-	-	< 1	-	-	-	-	-	-	-	-	<1	<1.2	-	-	-	-
Wylfa	Nearest site	-	-	329	< 10	-	<0.09	-	-	<0.4	<0.4	<0.4	<0.4	<0.4	<0.09	<0.09	<0.09	<0.4	<0.4	<0.4	-
Wylfa	Inner farms	-	-	323	<4.4		<0.09	-	-	<0.4	<0.4	<0.4	<0.4	<0.4	<0.09	<0.09	<0.09	<0.4	<0.4	<0.4	-

vegetables at Chapelcross.
Bq kg^-1 carbon.
There were no herbage sampled in 2007

Table 42. Radioactivity in milk in the vicinity of Magnox sites in 2007
Site^a	Location	Mean radionuclide concentration (Bq l^-1)
Site^a	Location	³ H	¹⁴C^b	³⁵S	⁴⁰ K	⁶⁰Co	⁶⁵Zn	⁹⁰Sr	⁹⁵Nb	⁹⁵ Zr	¹⁰⁶ Ru	^110m Ag	¹²⁵ Sb	¹³¹I	¹³⁴Cs	¹³⁷Cs	¹⁴⁴ Ce	¹⁵⁴ Eu	¹⁵⁵ Eu	²⁴¹ Am
Bradwell	Outer farms	-	259	-	52.4	<0.24	<0.53	<0.022	-	-	-	<0.2	-	-	<0.23	<0.22	-	-	-	<1.3
Bradwell	Control farms	-	256	-	58.9	<0.26	<0.63	<0.023	-	-	-	<0.21	-	-	<0.25	<0.24	-	-	-	<0.95
Chapelcross	Inner farms	15.3	241	<0.4	-	<0.03	-	0.03	-	-	-	-	-	<0.2	<0.03	<0.02	-	-	-	-
Chapelcross	Outer farms	<10	242	<0.4	-	<0.03	-	0.03	-	-	-	-	-	<0.05	<0.03	<0.03	-	-	-	-
Dungeness A	Farms	-	198	<0.91	-	<0.14	-	<0.021	<0.12	<0.5	<2.5	-	<0.77	<0.33	<0.44	<0.36	<3.7	<0.75	<1.8	-
Hinkley Point A	Inner farms	-	258	<1	-	<0.1	-	<0.03	<0.1	<0.2	<0.7	-	<0.3	-	<0.1	<0.1	<0.6	<0.2	<0.3	-
Hinkley Point A	Control farms	-	-	<0.8	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-
Hunterston A	Inner ring	<20	-	<0.43	-	<0.085	-	-	-	-	-	-	-	<0.48	<0.06	0.1	-	-	-	-
Hunterston A	Outer ring	<20	-	<0.52	-	<0.042	-	-	-	-	-	-	-	<0.44	<0.035	<0.097	-	-	-	-
Oldbury	Inner farms	-	298	<0.79	<47	<0.19	-	<0.028	<0.16	<0.26	-	-	<0.36	<0.16	<0.2	<0.19	<0.75	<0.2	<0.44	-
Sizewell A	Inner farms	-	246	<0.78	-	<0.18	-	<0.069	<0.23	<0.3	<1.3	-	<0.53	<0.21	<0.2	<0.23	<0.8	<0.28	<0.34	-
Sizewell A	Outer farms	-	286	<0.78	-	<0.16	-	<0.027	<0.18	<0.27	<1.2	-	<0.43	<0.19	<0.21	<0.2	<.1.1	<0.36	<0.65	-
Wylfa	Inner farms	-	170	<0.92	47.0	<0.29	-	-	<0.75	<0.75	<0.75	<0.75	<0.75	<0.29	<0.29	<0.29	<0.75	<0.75	<0.75	-
Wylfa	Outer farms	-	179	<0.9	46.4	<0.29	-	-	<0.75	<0.75	<0.75	<0.75	<0.75	<0.29	<0.29	<0.29	<0.75	<0.75	<0.75	-

Milk sampling is not required for Trawsfynydd and Berkeley. Oldbury's results are used for Berkeley's dose assessment.
Bq kg^-1 carbon.

In addition to statutory environmental monitoring programmes the sites are required to analyse soil cores by gamma-ray spectrometry. Cores are taken from pasture at one of five specified locations (local farms), rotating the location annually so that each location is sampled once every five years. Two types of core are taken: a shallow core (5 cm depth) which is used to determine specific activity (in Bq kg^-1) and a deep core (30 cm) used to determine the integrated deposition (in Bq m^-2). Results are presented in Table 43.

Table 43. Radioactivity in soil in the vicinity of Magnox sites in 2007
Site^a	Radionuclide
	Activity concentration (Bq kg^-1 dry weight)					Activity Loading (Bq m ^-2)
	Gross β	⁴⁰K	⁶⁰Co	¹³⁴Cs	¹³⁷Cs	Gross β	⁴⁰K	⁶⁰Co	¹³⁴Cs	¹³⁷Cs
Bradwell	604	365	2.68	2.93	16.1	120027	56158	366	386	2178
Dungeness A^b	940	-	<0.8	<1.4	<14	278395	-	<375	<358	2960
Hinkley Point A	630	-	<0.7	<0.8	7.6	131013	-	<234	<248	1495
Oldbury	799	814	<1.7	<1.5	8.0	58688	73053	<71	<119	442
Sizewell A	559	-	<1.0	<0.5	8.3	35051	-	<62	<31.0	511
Wylfa	604	-	<1.3	<1.5	34.5	56400	-	<120	<150	3120

Soil sampling is not required at Berkeley, Chapelcross, Hunterston A or Trawsfynydd.
No 30 cm deep soil sampling was obtainable at Dungeness A due to stony substrate of the ground.
Gross β (as ⁴⁰K)

The second addition to sites’ statutory environmental monitoring programmes is the requirement to deploy passive air samplers around the sites and analyse these by gamma-ray spectrometry. Results are shown in Table 44. Data for the natural radionuclides beryllium-7 and potassium-40 are included if reported, as these are indicators of the influence of cosmic radiation and dust loading, respectively. The results presented in Tables 43 and 44 are “baseline” data, as both quantities are useful primarily for trend analysis.

Table 44. Radioactivity on passive air samplers in the vicinity of Magnox sites in 2007
Site^a	Radionuclide (Bq per collector)
Site^a	⁷Be	⁴⁰K	⁶⁰Co	¹³¹I	¹³⁴Cs	¹³⁷Cs
Bradwell	-	<3.6	<0.29	-	<0.3	<0.3
Chapelcross^b	-	-	<1.3	-	<1.0	<1.1
Dungeness A	-	-	<0.3	<5.6	<0.59	<0.33
Hinkley Point A	-	-	<0.06	-	<0.07	<0.08
Oldbury and Berkeley	16.2	<8.6	<0.22	<0.5	<0.22	<0.3
Sizewell A	-	-	<0.14	<0.15	<0.15	<0.16
Wylfa	14.9	-	<0.23	<0.23	<0.23	<0.23

Deployment of passive air samplers is not required for Chapelcross, Hunterston A or Trawsfynydd.
Although there are no requirements for Chapelcross to report these, the measurements from passive air samplers are reported.

Bradwell is required to sample water from streams within 1 km of the site and analyse those samples for tritium and by gamma-ray spectrometry. All other radionuclides measured with the exception of potassium-40 were below the minimum detectable activity.

Tritium mean activity 13.8 Bq l^-1. Range 4 Bq l^-1 - 29 Bq l^-1.
Potassium-40 mean activity 4 Bq l^-1. Range 2.2 Bq l^-1 - 10.6 Bq l^-1.

4.2.1 Direct radiation

Two types of monitoring are carried out, the purpose in each case being to detect any differences from naturally occurring background radiation levels and to assess the radiation exposure to members of the public.

Environmental gamma dose rates are measured by a portable instrument at selected locations in the landward area surrounding each site. Measurement locations are distributed at approximately 30º intervals in inner (approximately 1 km) and outer (approximately 10 km) rings. Measurements are repeated over pasture at intervals of no more than three months. As the impact of Berkeley has diminished, the joint programme (Section 4.1) is performed by Oldbury.

The results are summarised in Table 45. Data are summarised as a mean of the inner and outer rings. Experience has shown that there is no significant difference in the dose rates in the inner and outer rings, therefore no distinction is made in the report. The most notable exception is at Dungeness A, where the dose rate in the inner ring has been significantly lower than that in the outer ring in previous years. This is due to a change of ground type from the inner ring, where the ground is shingle, to the outer ring, where the ground is soil. Consequently, from 2003 measurements in the outer ring are no longer required in the CEAR. The results are similar to previous years.

Table 45. Net gamma radiation dose rates measured in air over pasture in the vicinity of Magnox sites (µGy h^-1)^ain 2007
Site	Mean gamma dose rate (µGy h^-1) (corrected for background and cosmic radiation)
Berkeley	0.04
Bradwell	0.031
Dungeness A ^b	0.048
Hinkley Point A	0.046
Oldbury	0.037
Sizewell A	0.024
Trawsfynydd	0.051
Wylfa	0.038

No measurements made for Hunterston A or Chapelcross

Thermoluminescence dose meters (TLDs) are deployed on the perimeter fence and further afield around some sites in order to obtain a cumulative measurement of direct gamma radiation (integrated gamma radiation dose). They are changed every three months. Doses to members of the public at the critical location are assessed from these measurements (Section 5.4).

The results are given in Table 46. Data were summed across the year at each monitoring location, so that the range shows the total annual values for the least and most exposed locations at the site fence. The mean value is the annual average across all monitoring locations at the site fence; the value determined “nearest to the critical location” is that used for assessing public dose. The measurements include the local background together with any external gamma dose contribution from aerial discharges. Background is the average figure calculated from TLDs exposed in the environment around the site. In addition to cosmic background, there is a significant contribution from terrestrial gamma radiation, which varies according to local geology (Reference 29). Therefore, although TLDs are exposed typically up to 30 km around each site, in previous years only those between 0.1 and 2.5 km were used to assess the local background.

Table 46. Integrated gamma radiation dose measured around Magnox sites (µSv y^-1) in 2007
Site	Site Fence^a			Background
Site	Range	Mean	Nearest to Critical Location	Mean ^b	Standard Deviation
Berkeley	364 - 598	504	472	439	111
Bradwell	656 - 2247	1345	692	741	178
Chapelcross^{^c}	473 - 1715	804	1314	-	-
Dungeness A	331 - 866	459	372	555	174
Hinkley Point A	229 - 10593	1397	981	730	128
Hunterston A	496 - 1085	778	711	541	117
Oldbury	183 - 636	390	445	474	153
Sizewell A (Critical Habitation)	406 -1283	655	540	570	155
Sizewell A (Dog walkers)	-	-	851	-	-
Sizewell A (Fishermen, Anglers)	-	-	851	-	-
Sizewell A (Fishermen, Commershal)	-	-	588	-	-
Trawsfynydd	758 -1387	967	879	745	64
Wylfa	679 -1082	825	876	784	95

No correction made for background.
Mean of readings made using TLDs used for background correction.
Background not measured at Chapelcross.

5.0 Radiological impact of Magnox operations

5.1 Critical group doses

Doses to critical groups presented in this chapter are not always solely attributable to the Magnox sites, but include contributions from other sources, which may be of greater significance than the contribution from the Magnox site itself. In particular, doses from aquatic pathways around Chapelcross, Hunterston A and Wylfa are dominated by discharges from Sellafield. Thus, Sellafield’s discharges account for over 99% of the dose from aquatic pathways at Chapelcross. Similarly, discharges from the French reprocessing plant at Cap de la Hague contribute to doses around Dungeness A, Bradwell and Sizewell A. There are also small contributions to doses from aquatic pathways from discharges from the British Energy sites adjacent to Dungeness A, Hinkley Point A, Hunterston A and Sizewell A. The contribution to doses from terrestrial pathways may be more significant from these British Energy sites, especially at Hunterston and Hinkley Point where discharges of sulphur-35 from the Magnox sites are no longer detectable. However, doses due to direct radiation from British Energy stations are negligible (Reference 30), so the doses due to direct radiation reported in this chapter can be attributed primarily to the Magnox sites.

Doses from food consumption are presented in one of three ways, depending on the results of radionuclide measurements of the relevant food. Where all radionuclides are measurable, the dose from consumption of that food is presented as a single positive number. Where some radionuclides are measurable, but others are below the limit of detection, the dose from consumption of that food is presented as a range. The lower bound is determined assuming that measurements below the limit of detection are zero, the upper bound is determined assuming that they are equal to the limit of detection. Where all measurements are less than the limit of detection, the lower bound is zero, so the dose from consumption of that food is reported as below the upper bound.

5.2 Aquatic pathways

Critical group doses from consumption of seafood have been assessed from the measured concentrations of radionuclides in relevant foodstuffs (Table 34), the results of site-specific habit surveys published by FSA and SEPA (Reference 27) and the most recent dose coefficients in ICRP Publication 72 (Reference 31). No samples of crustacea from the area around Bradwell, Chapelcross, Berkeley and Oldbury were available to the Company and no samples of molluscs were available from areas around Chapelcross, Hinkley Point A, Oldbury and Berkeley. The FSA (Reference 27 ) however conduct independent surveys and data on activity in seafoods may be found in FSA (Reference 8). Where sites measured americium-241 in seafood (Table 34) the gamma-screening method was used because use of the more sensitive α spectrometry method is not cost-effective for the low doses from consumption of seafood. However, the gamma method often yields results below the limit of detection that give unrealistically high assessments of doses from consumption of seafood; therefore the average of americium-241 measurements from the last five RIFE reports has been averaged and used in the assessment of critical group doses. These data are recorded in Tables 34 a-h as americium-241 inferred.

Consumption and occupancy data for aquatic pathways are summarised in Table 47. Where consumption data are species specific, the relevant species data from Table 34 have been used, if available, in dose calculations. Otherwise, data for closely related species have been used, or if those are also unavailable, data have been averaged across the groups ‘fish’, ‘crustacea’ and ‘molluscs’, as appropriate. It has been assumed that consumption of non-critical foods generally add about a further 10% of dose to the dose from consumption of critical foods (Reference 32).

Table 47. Consumption and occupancy data for aquatic critical groups in the vicinity of Magnox sites (Reference 27)
Site^a	Consumption, kg y^-1				Exposure over sediments
Site^a	Fish	Crustacea	Molluscs	Other species	h y^-1	Substrate
Berkeley & Oldbury (2007)	14 (eels and other fish)	2.7 (shrimp)	-	-	900	Mud, stones and saltmarsh
Bradwell (2007)	25	1.1(crabs and lobsters)	2.9 (Pacific and European oysters)	-	3100	Mud
Chapelcross (A) (2005)	31 (salmonids)	-	-	-	950	Mud
Chapelcross (B) (2005)	-	-	-	19 (wildfowl)	450	Salt marsh
Chapelcross (C) (2005)	-	-	-	-	390	Handling nets
Chapelcross (C) (2005)	-	-	-	-	610	Handling sediment
Dungeness A (A) (2005)	51	9.3 (crabs & shrimp)	17 (king scallop)	-	1500	Mud & sand
Dungeness A (B) (2005)				-	2000	Rye Harbour house boats over mud
Hinkley Point A (2006)	40	12 (shrimp)	1.9 (whelk)	-	1300	Mud
Hunterston A (2007)	47	18 (Nephrops & squat lobster)	21 (king scallop)	-	440	Mud, sand or stones
Sizewell A (2005)	23	11 (Crab & lobster)	5.1 (Pacific oyster & mussel)	-	720	Mud
Trawsfynydd (2005)	1.3 (Brown trout)	-	-		450	Lake shore
	60 (Rainbow trout)

Wylfa (2004)	22	6.5 (Crab & lobsters)	1.5		270	Sand and stones

Where there is more than one critical group, separate groups are denoted (A), (B) etc.

Tables 48 and 49 present contributions to critical group doses by pathway and radionuclide respectively. Doses from ingestion are frequently dominated by the upper bound concentration of americium-241. Otherwise, doses are dominated by ingestion of caesium-137. Results are similar to those of recent years.

Table 48. Critical group (adult) doses from consumption of sea foods in the vicinity of Magnox sites by pathway (µSv) in 2007
Site	Fish	Crustacea	Molluscs	Other pathways	Total
Bradwell	< 1.6	< 0.03	< 0.1	0.2	< 1.9
Chapelcross	2.5 - 3.5	-	-	0.3	2.5 - 3.8
Dungeness A	< 1.9	< 0.5	< 0.3	0.3	< 3.0
Hinkley Point A	0.4 - 1.3	0.1 - 0.2	< 0.05	0.2	0.5 - 1.7
Hunterston A	0.9 - 2.6	0.1 - 0.6	0.3 - 0.9	0.4	1.3 - 4.4
Oldbury & Berkeley	< 0.6	0.001	-	0.06	0.001 - 0.7
Sizewell A	< 0.7	0.002 - 0.1	<0.2	0.1	0.002 - 1.1
Wylfa	0.9 - 1.7	0.05 - 0.2	0.074 - 0.077	0.2	1.0 - 2.2

Table 49. Critical group (adult) doses from consumption of sea foods in the vicinity of Magnox sites by radionuclide (µSv) in 2007
Site	⁶⁰Co	⁶⁵Zn	⁹⁰Sr	^110mAg	¹³⁴Cs	¹³⁷Cs	²⁴¹Am
Bradwell	< 0.06	< 0.2	-	< 0.05	< 0.3	< 0.3	< 0.9
Chapelcross	< 0.01	< 0.01	< 0.09	< 0.009	< 0.06	2.5	< 0.8
Dungeness A	< 0.07	-	-	-	< 0.4	< 0.5	< 1.8
Hinkley Point A	< 0.06	-	-	-	< 0.3	0.5	0.002 - 0.7
Hunterston A	< 0.2	-	-	-	-	1.3	< 2.5
Oldbury & Berkeley	< 0.01	-	-	-	< 0.06	< 0.08	0.001 - 0.5
Sizewell A	< 0.04	-	-	-	< 0.2	< 0.2	0.002 - 0.6
Wylfa	0.09 - 0.1	-	-	-	-	0.8	0.06 - 1.0

Data for the radionuclide concentrations in the fish species sampled from Trawsfynydd Lake (Table 38) have been used with site-specific consumption data (Reference 27) (Table 47) and the most recent dose coefficients (Reference 31) to assess the dose from consumption of fish from the lake (Table 50). Although samples of perch were analysed this species is no longer consumed and is therefore not evaluated in Table 50. Doses are dominated by ingestion of caesium-137 and caesium-134. Doses are similar to those in recent years.

Table 50. Critical group (adult) doses to consumers of fish from Trawsfynydd Lake (µSv) in 2007
Foodstuff	⁶⁰ Co	⁹⁰ Sr	¹³⁴Cs	¹³⁷Cs	²⁴¹Am	²³⁸Pu	^239/40Pu	Total
Rainbow trout	<0.1	<0.6	<1	<0.5	<0.06	<0.04	<0.1	<2.4
Brown trout	<0.002	<0.01	<0.01	0.6	<0.0007	<0.0009	<0.002	<0.6
Total	<0.1	<0.6	<1	<1	<0.06	<0.04	<0.1	<3

Doses from external exposure are shown in Table 51. The data used to calculate the dose rates are the gross values measured by the sites i.e. with no background and cosmic contribution subtracted. The background and cosmic contributions contributions, averaged over all substrates for the North West, South West and South East were then subtracted. Where appropriate, they have been added to the doses from consumption of fish and seafood to yield the doses summarised in Table 1. Where a range of doses is reported for consumption the upper bound figure has been used for Table 1.

Table 51. Critical group doses in the vicinity of Magnox sites from external exposure associated with aquatic discharges (µSv) in 2007
Site	Dose (µSv)
Berkeley	33
Bradwell	55
Chapelcross (A)	7.6
Chapelcross (B)	5.5
Dungeness A	5.9
Hinkley Point A	31
Hunterston A	10
Oldbury	34
Sizewell A	5.8
Trawsfynydd	13
Wylfa	8.8

5.3 Airborne and terrestrial pathways

Critical group doses from consumption of terrestrial foods have been assessed from the observed concentrations of radionuclides in grass and milk (Tables 41 and 42), national consumption data for the UK (Reference 27), and the most recent dose coefficients (Reference 31). Monitoring of terrestrial foodstuffs required in the SEMP extends only to milk, although the sampling of grass is also required. Therefore, data for radionuclides in milk have been used directly, whereas it has been assumed that data for grass (Table 41) may be applied to green vegetables and legumes.

The FSA (Reference 33) recommends that the two foodstuffs contributing most to the critical group dose are assigned critical consumption rates and national average consumption rates are assumed for other foods. However, this approach requires several foodstuffs to be monitored, but only the monitoring of milk is required of Magnox sites by the EA although the concentration of radionuclides in some other foods is inferred from data on grass. Therefore, critical consumption rates (Reference 27) have been assigned to milk, green vegetables and legumes (Table 52) and it has been assumed that consumption of non-critical foods generally adds about a further 10% of dose to the dose from consumption of critical foods (Reference 32).

Table 52 Consumption data for terrestrial critical groups in the vicinity of Magnox sites (Reference 27)
Foodstuff	Consumption (kg y^-1) ^a
Foodstuff	Adult	Child	Infant
Milk	240	240	320
Legumes^b	50	25	10
Green vegetables	45	20	10

These are the above average consumption rates i.e. the 97 ^th percentile of the distribution across all consumers
Consumption of legumes not included for Chapelcross.

Doses to adults, showing the contribution from individual pathways, are given in Table 53. As the same concentration data were applied to higher rate consumption of both green vegetables and legumes, the results for these two categories are grouped together as ‘vegetables’. Contributions to the critical group doses by individual radionuclides are shown in Table 54. Equivalent data for children and infants are given in Tables 55 to 58. The results of the assessments are dominated by ingestion of iodine-131 in milk, where iodine-131 is still reported. As these results are mainly upper bound figures, the actual ingestion doses may be lower. Doses are broadly similar to last year.

Table 53. Critical group (adult) doses from the consumption of milk and vegetables in the vicinity of Magnox sites (by pathway) (µSv) in 2007
Site	Vegetables	Milk	Other Pathways (µSv)	Total
Bradwell	0.003 - 2.4	0.08 - 2.2	0.5	0.08 - 5.1
Chapelcross	1.4 - 1.8	0.2 - 1.2	0.3	1.6 - 3.3
Dungeness A ^a	< 0.9	< 5.2	0.6	< 6.7
Hinkley Point A ^a	< 1.0	0.08 - 1.3	0.2	0.08 - 2.5
Hunterston A ^a	-	0.3 - 3.1	0.3	0.3 - 3.4
Oldbury and Berkeley	< 3.5	0.5 - 3.2	0.7	0.5 - 7.4
Sizewell A ^a	0.4 - 3.5	0.2 - 3.3	0.7	0.6 - 7.5
Trawsfynydd ^b	< 3.6	-	0.4	< 4
Wylfa	0.2 - 0.8	< 4.0	0.5	0.2 - 5.3

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

Table 54. Summary of doses to terrestrial critical groups (adult) in the vicinity of Magnox sites from the consumption of milk and vegetables (by radionuclide) (µSv) in 2007
Site	Critical Vegetables + Milk, µSv
Site	³ H	¹⁴ C	³⁵ S	⁶⁰ Co	⁹⁰ Sr	¹³¹ I	¹³⁴ Cs	¹³⁷ Cs
	³ H	¹⁴ C			⁹⁰ Sr	¹³¹ I	¹³⁴ Cs
Bradwell	-	0.08	-	< 0.4	< 0.2	-	< 2.4	< 1.6
Chapelcross	0.09 - 0.1	-	< 0.04	< 0.06	1.5	< 0.7	< 0.3	< 0.2
Dungeness A ^a	-	-	< 0.08	< 0.1	< 0.1	< 2.1	< 2.3	< 1.3
Hinkley Point A ^a	-	0.08	< 0.03	< 0.2	< 0.2	-	< 1.1	< 0.8
Hunterston A ^a	< 0.09	-	< 0.01	< 0.05	-	< 2.4	< 0.2	0.2 - 0.3
Oldbury and Berkeley	-	0.5	< 0.05	< 0.4	< 0.2	<1.9	< 2.1	< 1.6
Sizewell A ^a	-	0.5	< 0.08	< 0.3	< 0.3	< 2.3	< 2.0	< 1.3
Trawsfynydd ^b	-	-	-	< 0.3	-	-	< 1.8	< 1.5
Wylfa	-	0.2	< 0.1	< 0.2	-	< 1.7	< 1.5	< 1.0

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

Table 55. Critical group (child) doses from the consumption of milk and vegetables in the vicinity of Magnox sites (by pathway) (µSv) in 2007
Site	Vegetables	Milk	Other Pathways (µSv)	Total
Site
Bradwell	0.002 - 1.1	0.1 - 2.4	0.4	0.1 - 3.9
Chapelcross	1.4 - 1.6	0.5 - 2.3	0.4	1.9 - 4.3
Dungeness A ^a	< 0.7	< 7.2	0.8	< 8.7
Hinkley Point A ^a	< 0.5	0.1 - 1.5	0.2	0.1 - 2.2
Hunterston A ^a	-	0.2 - 6.4	0.6	0.2 - 7
Oldbury and Berkeley	< 2.3	0.7 - 4.7	0.7	0.7 - 7.7
Sizewell A ^a	0.3 - 2.5	0.2 - 5.1	0.8	0.5 - 8.4
Trawsfynydd ^b	< 1.7	-	0.2	< 1.9
Wylfa	0.2 - 0.6	< 6.1	0.7	0.2 - 7.4

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

Table 56 Summary of doses to terrestrial critical groups (child) in the vicinity of Magnox sites from the consumption of milk and vegetables (by radionuclide) (µSv) in 2007
Site	Critical Vegetables + Milk, µSv
Site	³ H	¹⁴ C	³⁵ S	⁶⁰ Co	⁹⁰ Sr	¹³¹ I	¹³⁴ Cs	¹³⁷ Cs
	³ H	¹⁴ C			⁹⁰ Sr	¹³¹ I	¹³⁴ Cs
Bradwell	0.0	0.1	-	< 1.0	< 0.3	-	< 1.3	< 0.9
Chapelcross	0.08 - 0.1	-	< 0.05	< 0.1	1.8	< 1.6	< 0.2	< 0.1
Dungeness A ^a	-	-	< 0.1	< 0.4	< 0.3	< 4.5	< 1.6	< 0.9
Hinkley Point A ^a	-	0.1	< 0.06	< 0.4	< 0.4	-	< 0.6	< 0.4
Hunterston A ^a	< 0.1	-	< 0.03	< 0.2	-	< 5.7	< 0.2	0.2 - 0.3
Oldbury and Berkeley	-	0.7	< 0.08	< 0.8	< 0.4	< 3.2	< 1.1	< 0.8
Sizewell A ^a	-	0.5	< 0.1	< 0.7	< 0.7	< 3.8	< 1.0	< 0.8
Trawsfynydd ^b	-	-	-	< 0.5	-	-	< 0.6	< 0.5
Wylfa	-	0.2	< 0.1	< 0.8	-	< 3.8	< 1.0	< 0.7

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

Table 57. Critical group (infant) doses from the consumption of milk and vegetables in the vicinity of Magnox sites (by pathway) (µSv) in 2007
Site	Vegetables	Milk	Other Pathways (µSv)	Total
Bradwell	0.002 - 0.8	0.3 - 5.1	0.6	0.3 - 6.5
Chapelcross	0.8 - 0.9	0.9 - 8.7	1.0	1.7 - 11
Dungeness A ^a	< 0.8	< 25	2.6	< 28
Hinkley Point A ^a	< 0.3	0.3 - 3.1	0.3	0.3 - 3.7
Hunterston A ^a	-	0.4 - 28	2.8	0.4 - 31
Oldbury and Berkeley	< 2.6	1.8 - 15	1.8	1.8 - 17
Sizewell A ^a	0.2 - 3.0	0.6 - 17	2.0	0.8 - 22
Trawsfynydd ^b	< 1.1	-	0.1	< 1.2
Wylfa	0.1 - 0.7	< 22	2.3	0.1 - 25

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

Table 58. Summary of doses to terrestrial critical groups (infant) in the vicinity of Magnox sites from the consumption of milk and vegetables (by radionuclide) (µSv) in 2007
Site	Critical Vegetables + Milk, µSv
Site	³ H	¹⁴ C	³⁵ S	⁶⁰ Co	⁹⁰ Sr	¹³¹ I	¹³⁴ Cs	¹³⁷ Cs
	³ H	¹⁴ C			⁹⁰ Sr	¹³¹ I	¹³⁴ Cs
Bradwell	-	0.3	-	< 2.5	< 0.5	-	< 1.5	< 1.0
Chapelcross	0.09 - 0.1	-	< 0.1	< 0.3	1.4	< 7.2	< 0.2	< 0.1
Dungeness A ^a	-	-	< 0.3	< 1.3	< 0.5	< 20	< 2.3	< 1.4
Hinkley Point A ^a	-	0.3	< 0.3	< 1.0	< 0.6	-	< 0.8	< 0.5
Hunterston A ^a	< 0.3	-	< 0.1	< 0.5	-	<26	< 0.2	0.2 - 0.3
Oldbury and Berkeley	-	1.8	< 0.3	< 2.0	< 0.6	<11	< 1.2	< 0.9
Sizewell A ^a	-	0.8	< 0.3	< 1.8	< 1.1	< 14	< 1.2	< 1.0
Trawsfynydd ^b	-	-	-	< 0.5	-	-	< 0.3	< 0.3
Wylfa	-	0.1	< 0.4	<2.5	-	< 17	< 1.5	< 1.1

Includes contribution from neighbouring BE site
Milk sampling is not required at Trawsfynydd

External radiation and inhalation dose per unit activity discharged have been assessed for a range of radionuclides at each site using a Gaussian plume model for the dispersion, using the methodology (Reference 34) based on the recommendations of the HPA (Reference 35). The resultant concentrations in air have been applied with occupancy data, discharge data and either dose per unit intake data for inhalation (Reference 31) to estimate inhalation dose or mean gamma decay energies to calculate direct radiation dose from the discharge plume. β particulate is dominated by cobalt-60 at most sites. Therefore, cobalt-60 has been considered to be representative of β particulate.

Exposure has been assessed for occupancy at the critical habitation for each site, together with any other candidate group that may have been identified. Occupancy inside and outside is given in hours per year for each group in Table 59. For critical habitations, BNFL default assumptions for occupancy have been adopted for all Magnox sites, i.e. the fraction of time spent indoors is 50% for farmers and 90% for the general population. No allowance is made for time spent away from home. Actual occupancy data (where available) show these assumptions to be reasonably pessimistic. Where time is spent indoors, a shielding factor of 0.2 is applied to calculate the dose from direct gamma radiation by the discharge plume.

Table 59. Occupancy data for terrestrial critical groups in the vicinity of Magnox sites
Site^a	Occupancy^b,c, h y ^-1
Site^a	Inside	Outside
Berkeley	4380	4380
Bradwell	7884	876
Chapelcross	5830	510
Dungeness A	7884	876
Hinkley Point A	4380	4380
Hunterston A	4380	4380
Oldbury	4380	4380
Sizewell A (A)	7884	876
Sizewell A (B) (fishermen)	-	3650
Sizewell A (C)	-	250
Sizewell A (D)	-	90
Trawsfynydd	4380	4380
Wylfa	7884	876

Where there is more than one critical group, separate groups are denoted (A), (B) etc
Occupancy data also apply to assessment of critical group dose from direct radiation.
Occupancy data apply to critical habitation, except for Sizewell A where (B) applies to fishermen, (C) to anglers and (D) to dog walkers.

Inhalation and external doses to adults for each site (assessed from the dispersion model) are presented in Table 60. Those to children and infants are shown in Tables 61 and 62. Children and infants are not considered for Sizewell A’s group B, which consists of commercial fishermen. Additionally, infants are not considered for Sizewell A’s group C, which consists of sports anglers, although it is reasonable to expect that children may be present in this group. Sizewell A’s group D consists of people walking their dogs on the beach. As this activity may involve whole family groups, both children and infants have been considered. For the two generating stations dose from the plume is dominated by argon-41. The relevant pathway is external radiation from the plume itself. For other radionuclides, the dominant pathway is inhalation, except for β particulate (cobalt-60) which is dominated by external radiation from activity deposited from the plume on to the ground (ground gamma). For decommissioning sites, doses are attributable mainly to tritium (inhalation) and β particulate (ground gamma). With the exception of Dungeness A and Sizewell A which ceased generation at the end of 2006, doses are similar to those reported in 2006. Doses to adults from consumption (Table 53) have been added to those from the plume to determine which age group’s dose is summarised in Table 2 (which excludes doses from argon-41 where these are included in the measurement of direct radiation).

Table 60. Summary of inhalation and external doses to adult terrestrial critical groups from discharges to air (µSv) in 2007
Site	Group	³H	¹⁴C	³⁵S	⁴¹Ar	β particulate	Total	Total exc. ⁴¹Ar^b
Berkeley	Critical habitation	0.000048	0.000091	-	-	0.00085	0.001	0.001
Bradwell	Critical habitation	0.00016	0.00025	-	-	0.00043	0.00085	0.00085
Chapelcross	Critical habitation	0.19	0.0000088	0.00001	-	-	0.19	0.19
Dungeness A	Critical habitation	0.0022	0.078	0.00014	-	0.016	0.097	0.097
Hinkley Point A	Critical habitation	0.00014	0.000032	-	-	0.00002	0.00019	0.00019
Hunterston A	Critical habitation	0.0000065	0.000023	-	-	0.000054	0.000084	0.000084
Oldbury	Critical habitation	0.0055	0.044	0.00046	0.12	0.0022	0.18	0.052
Sizewell A (A)	Critical habitation	0.0039	0.011	0.00041	-	0.00019	0.016	0.016
Sizewell A (B)^a	Fishermen	0.0014	0.0041	0.00014	-	0.00027	0.0058	0.0058
Sizewell A (C)^a	Anglers	0.00064	0.0019	0.000067	-	0.00011	0.0027	0.0027
Sizewell A (D)	Dog walkers	0.00078	0.0023	0.000082	-	0.000096	0.0033	0.0033
Trawsfynydd	Critical habitation	0.00062	0.00044	-	-	0.00006	0.0011	0.0011
Wylfa	Critical habitation	0.011	0.13	0.0042	0.13	0.029	0.3	0.17

Additive to dose from consumption of seafoods.
Where the dose from argon-41 is included in the measurement of direct radiation dose.

Table 61. Summary of inhalation and external doses to child terrestrial critical groups from discharges to air (µSv) in 2007
Site	Group	³H	¹⁴C	³⁵S	⁴¹Ar	β particulate	Total	Total exc. ⁴¹Ar^b
Berkeley	Critical habitation	0.00004	0.000084	-	-	0.00047	0.0006	0.0006
Bradwell	Critical habitation	0.000087	0.00015	-	-	0.00016	0.00039	0.00039
Chapelcross	Critical habitation	0.17	0.0000083	0.0000099	-	-	0.17	0.17
Dungeness A	Critical habitation	0.0016	0.063	0.00011	-	0.013	0.078	0.078
Hinkley Point A	Critical habitation	0.000062	0.000015	-	-	0.0000042	0.000081	0.000081
Hunterston A	Critical habitation	0.000003	0.000014	-	-	0.000017	0.000034	0.000034
Oldbury	Critical habitation	0.0028	0.024	0.00024	0.04	0.00057	0.068	0.028
Sizewell A (A)^a	Critical habitation	0.0017	0.0055	0.00018	-	0.00004	0.0074	0.0074
Sizewell A (C)^a	Anglers	0.00028	0.00095	0.000031	-	0.000023	0.0013	0.0013
Sizewell A (D)^a	Dog walkers	0.00034	0.0012	0.000037	-	0.00002	0.0015	0.0015
Trawsfynydd	Critical habitation	0.0003	0.00024	-	-	0.000016	0.00055	0.00055
Wylfa	Critical habitation	0.0061	0.077	0.0024	0.048	0.01	0.14	0.096

Children are not included in Sizewell A group B, which is composed of commercial fishermen.
Where the dose from argon-41 is included in the measurement of direct radiation dose.

Table 62. Summary of inhalation and external doses to infant terrestrial critical groups from discharges to air (µSv) in 2007
Site	Group	³H	¹⁴C	³⁵S	⁴¹Ar	β particulate	Total	Total exc. ⁴¹Ar^b
Berkeley	Critical habitation	0.000026	0.000057	-	-	0.0004	0.00048	0.00048
Bradwell	Critical habitation	0.000057	0.0001	-	-	0.00012	0.00028	0.00028
Chapelcross	Critical habitation	0.14	0.0000066	0.0000087	-	-	0.14	0.14
Dungeness A	Critical habitation	0.0011	0.043	0.00008	-	0.012	0.056	0.056
Hinkley Point A	Critical habitation	0.00004	0.00001	-	-	0.000004	0.000053	0.000053
Hunterston A	Critical habitation	0.000002	0.000009	-	-	0.000015	0.000026	0.000026
Oldbury	Critical habitation	0.0018	0.016	0.00018	0.038	0.0005	0.056	0.019
Sizewell A (A)^a	Critical habitation	0.0011	0.0037	0.00014	-	0.000035	0.005	0.005
Sizewell A (D)^a	Dog walkers	0.00022	0.00077	0.000028	-	0.000018	0.001	0.001
Trawsfynydd	Critical habitation	0.0002	0.00016	-	-	0.000013	0.00037	0.00037
Wylfa	Critical habitation	0.0039	0.052	0.0018	0.045	0.0083	0.11	0.066

Infants are not included in Sizewell A group B, which is composed of commercial fishermen or in Sizewell group C, which is composed of sports anglers.
Where the dose from argon-41 is included in the measurement of direct radiation dose.

5.4 Direct radiation

The assessments for 2007 are presented in Tables 63 (assessed annual dose from direct radiation) and 46 (summary information relating to dose rate at the site fence). Where more than one candidate reference group for direct radiation has been identified at a site, data for each of those groups are presented, identified by the letters (A), (B) etc.

In common with last year, dose rate at the site fence has been assessed at the 95% confidence level to be consistent with the requirements of the Environment Agency. If the measurement at the site fence exceeds the mean background by more than 1.96 standard deviations, then the dose is assessed from the measurement at the fence (less background), extrapolated to the critical location using inverse square law (the mid-point of the reactors acting as the reference point). Otherwise the dose rate at the site fence is estimated as background plus 1.96 standard deviations and the result is expressed as “<” in Table 63. A shielding factor of 0.2 has been applied to a dwelling for direct gamma radiation. Occupancy data are the same as those used to assess dose from direct radiation from the plume.

Measurements of background by TLD are not made at Chapelcross. In previous years the direct dose for Dungeness A included neutron radiation, which contributed significantly to the public dose. However, since cessation of generation in December 2006 there is no longer a neutron component to the direct radiation dose.

Doses for 2007 are generally similar to those for 2006 for all sites and at many of the decommissioning and defuelling sites are decreasing.

Table 63. Direct radiation doses to the most exposed members of the public at Magnox sites (µSv) in 2007
Site	Group	Gamma dose (µSv)
Berkeley	Critical habitation	< 60
Bradwell	Critical habitation	< 62.9
Chapelcross	Critical habitation	< 1
Dungeness A	Critical habitation	280
Hinkley Point A	Critical habitation	3.4
Hunterston A	Critical habitation	< 81.3
Oldbury	Critical habitation	< 6.9
Sizewell A (A)	Critical habitation	< 32.6
Sizewell A (B)	Fishermen	< 15.1
Sizewell A (C)	Anglers	3.5
Sizewell A (D)	Dog walkers	2.7
Trawsfynydd	Critical habitation	15.5
Wylfa	Critical habitation	<10.1

The most exposed group from each site represents the critical group for direct radiation, summarised in Table 3.

5.4.1 Summary of critical group doses

Doses to members of the public from discharges to water, discharges to air and from direct radiation have been considered separately above. The most exposed group of the public local to each site in 2007 constitutes the critical group for that year. Depending on the additive impact of each of these operations, the critical group could be represented by a group of people exposed through a single operation (e.g. discharges of liquid wastes) or through a combination of different operations (e.g. direct radiation and discharges of radioactivity to air). Where fishermen are exposed to the gaseous discharge plume or direct radiation, the resultant dose is added to the dose due to liquid discharges, rather than the dose due to gaseous discharges via consumption. Critical group doses for the sites are summarised in Table 4.

5.4.2 Collective doses

Collective doses resulting from discharges from Magnox sites, shown in Table 64, have been calculated in accordance with Section 1.4.3 and 1.6 of the Introduction. The collective dose to the population of the UK from operation of the Magnox fleet was 0.7 manSv (78 % from discharges of carbon-14, 14% from discharges of tritium and 6.6 % from discharges of sulphur -35). The significant reduction in the percentage contribution from argon-41 is directly attributable to the cessation of generation at Sizewell A and Dungeness A that are both steel pressure vessel stations and were the major contributors to the generation of this radionuclide whilst they were generating. The collective dose to the population of Europe was 5 manSv (92 % from discharges of carbon-14 and 4.4 % from discharges of tritium, and 3.0% from discharges of sulphur-35) and that to the world population was 32 manSv (99% from discharges of carbon-14). The collective dose commitments from generating stations are dominated by the dose from aerial discharges of carbon-14 because of its long radioactive half-life (5760 years) and its incorporation into the global carbon cycle. In contrast, collective dose commitments from liquid discharges are negligible. However, because the discharges of carbon-14 from decommissioning sites are several orders of magnitude lower than those from generating stations, dose commitments from liquid discharges are comparable to those from aerial discharges. With the exception of Dungeness A and Sizewell A, collective doses were generally similar to those reported last year.

Table 64. Collective dose commitments from discharges from Magnox sites (man Sv) in 2007
Site	Doses from aerial discharges, manSv			Doses from liquid discharges, manSv
Site	UK	Europe	World	UK	Europe	World
Berkeley	0.00015	0.00078	0.0048	0.0000002	0.0000011	0.0000011
Bradwell	0.00058	0.0035	0.021	0.00026	0.00099	0.0011
Chapelcross	0.085	0.19	0.22	0.0000067	0.000016	0.000019
Dungeness A	0.077	0.72	4.6	0.00056	0.0032	0.0037
Hinkley Point A	0.0004	0.0022	0.014	0.00073	0.0038	0.004
Hunterston A	0.000046	0.0004	0.0033	0.00000018	0.0000007	0.00000088
Oldbury	0.14	0.9	6.0	0.0011	0.0052	0.0056
Sizewell A	0.046	0.34	2.1	0.0032	0.015	0.018
Trawsfynydd	0.00089	0.0068	0.05	0.000027	0.000066	0.000075
Wylfa	0.32	2.5	19.0	0.000094	0.00022	0.0005

Substance	Peak concentration (mg m ^-3)
	Dungeness A		Wylfa
	Limit	Discharge	Limit	Discharge
Carbon monoxide	100	4.9	100	1.46
Organic compounds (excluding particulate matter)	20	0.12	20	<0.01
Total particulate matter	200	95	120	108
Heavy metals	5	1.32	5	0.75
Chlorine (as hydrogen chloride)	250	207	250	30.7
Sulphur dioxide	300	251	300	98.6

Site^a	Hazardous (t)	Non-hazardous (t)	Inert (t)
Berkeley	5	65 (Landfill) 48 (Metal)	80
Bradwell	1352 ^b	1656	323
Chapelcross	-	324 (landfill)	-
Dungeness A	13	60	0
Hinkley Point A	78	6615	-
Oldbury	27	535	96171 ^c
Sizewell A	31	300	0
Trawsfynydd	21	122 (landfill)	220
Wylfa	45	158	9.4
Maentwrog	-	-	25 ^d

Summary