§ Mr. D. E. Thomasasked the Secretary of State for Wales if he will publish a list of the estimated maximum exposures of members of the public in respect of Trawsfynydd nuclear power station, showing (a) the dose equivalent for each year of operation, expressed in millisieverts and (b) the average dose equivalent of the 10-year period ending in each recent year, expressed in millisieverts; what changes are expected to take place concerning maximum exposures of members of the public; and if he will make a statement.
§ Mr. Mark Robinson(a) The data are all available in MAFF annual reports entitled "Radioactivity in Surface and Coastal Waters of the British Isles", copies of which are available in the Library of the House. The close equivalent (m Sv) to the critical group resulting from the discharge of liquid effluent into Lake Trawsfynydd for each year of operation is as follows:
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Prior to 1968 Too low to measure accurately 1968 0.2 1969 0.2 1970 0.15 1971 0.25 1972 0.3 1973 0.3 1974 0.35 1975 0.4 1976 1.05
Prior to 1968 Too low to measure accurately 1977 0.15 1978 <0.1 1979 <0.1 1980 <0.15 1981 0.55 1982 0.35 1983 0.25 1984 0.32 1985 0.21 (b) The average annual dose equivalent (m Sv) for 10-year periods (assuming the dose for 1978 and 1979 lo be 0.1 m Sv each year and the dose for 1980 to be 0.15 m Sv). 1968–77 0.34 1969–78 0.33 1970–79 0.32 1971–80 0.32 1972–81 0.35 1973–82 0.35 1974–83 0.35 1975–84 0.34 1976–85 0.32 We do not expect any major change to the exposures of members of the public, but the situation will be kept under review.
§ Mr. D. E. Thomasasked the Secretary of State for Wales what information is available to his Department of the additional exposure to radiation of members of the public expected to arise from the prospective new nuclear power station at Trawsfynydd; what assessment level would be used in the safety case for a new station in respect of the maximum radiation exposure of any member of the public during normal operations; and if he will make a statement.
§ Mr. Mark RobinsonNo decisions have been taken by the CEGB about the timing of the closure of the present station at Trawsfynydd, or about whether it should be replaced.
If any further nuclear power station were to be constructed at Trawsfynydd, any additional exposure to members of the public would depend on the type of station constructed and it is not possible to make a precise calculation at this stage. However, the criteria recommended by ICRP will be fully taken into account in assessing the safety case for any such power station.
§ Mr. D. E. Thomasasked the Secretary of State for Wales whether his Department provided information to the Radioactive Waste Management Advisory Committee relevant to the study of liquid radioactive discharges from Trawsfynydd nuclear power station mentioned in the sixth annual report of that body; what reports his Department has received of that study; whether any further studies have been undertaken or commissioned; and if he will make a statement.
§ Mr. Mark RobinsonThe information was provided by the Directorate of Fisheries Research at the request of the Department, which received a copy of the relevant paper. The directorate carries out an extensive programme of monitoring in the aquatic environment around major United Kingdom nuclear sites, including the effects of liquid radioactive discharges from Trawsfynydd nuclear power station. The results are published annually by MAFF in a series of reports entitled "Radioactivity in Surface and Coastal Waters of the British Isles".
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§ Mr. D. E. Thomasasked the Secretary of State for Wales if, further to his reply to the hon. Member for Merionnydd Nant Conwy on 12 December, Official Report, column 317, concerning the estimated doses of radioactivity received by critical groups in respect of Trawsfynydd nuclear power station, he will state (a) what members of the public comprise the critical group mentioned, (b) what pathway or pathways of exposure are relevant for members of that critical group and (c) the annual number of sample measurements used to derive the estimated annual doses received by members of that critical group; and if he will make a statement.
§ Mr. Mark Robinson(a) The members of the public comprising the critical group are anglers who consume rainbow and brown trout caught in the Lake.
(b) The relevant pathway is internal irradiation from the consumed fish.
(c) Approximately four samples per year each of rainbow and brown trout are analysed on behalf of the Department to assess the critical group dose. Each sample consists of approximately six individual fish. Further, more numerous analyses are carried out by the site operator as a condition of authorisation. The results of these two programmes are in agreement. The actual numbers of samples vary somewhat from year to year depnding on availability.