HL Deb 18 December 1984 vol 458 cc638-40WA
The Earl of Cranbrook

asked Her Majesty's Government:

What measures are being taken to reduce liquid discharges of radioactivity from Sellafield.

The Parliamentary Under-Secretary of State, Department of the Environment (The Earl of Avon)

The Radiochemical Inspectorate of my department, jointly with the Ministry of Agriculture. Fisheries and Food, have already put forward formal proposals for a variation of the authorisation under the Radioactive Substances Act 1960, so that the limits will reflect the substantial reductions in actual discharges that have been achieved in the past few years and place extra controls on the amounts discharged over short periods, and on solvent and particulates. This variation, which also contains a formal requirement that the best practicable means must be used to limit discharges, is expected to come into force early in the New Year.

The Site Ion Exchange Plant (SIXEP), constructed at a cost of £130 million, will come into operation next year and will make possible a further reduction in discharges of caesium, to one-tenth of the maximum released in recent years. The new salt evaporator, also due to come into operation next year at a cost of £30 million, will make possible a parallel reduction in discharges of plutonium and other alpha emitters, to about 200 curies a year. Formal proposals to replace the existing authorisation by a new and more stringent one will be put forward by the authorising departments next year, and the opportunity will also he taken to set specific limits on a much larger number of individual radionuclides. The local authorities will be consulted about the new draft authorisation, as will the water and health authorities, and sea fisheries committees.

Beyond that, the achievement of a further significant reduction on a continuing basis depends on the construction of major new treatment plant. The Government, after a review of the options in consultation with the company, have approved the company's proposal to build a floc precipitation plant, costing £150 million, which would be in operation by 1991. The target is to reduce discharges to less than 20 curies a year of alpha activity and about 8,000 curies a year of beta/gamma activity (other than tritium). The latter figure is below the level currently achieved by the only plant in any way comparable, the newer French reprocessing plant at Cap de la Hogue, and the alpha figure is approximately equal to the current figure for that plant. These figures include an allowance for the new reprocessing plant for oxide fuel. Further reductions will be obtained when the present reprocessing plant for magnox fuel goes out of operation in the early years of the next century. At that time the target will be to reduce discharges to not more than 5 curies a year of alpha activity and not more than 2,000 curies a year of beta/gamma activity (other than tritium).

This programme of measures complies with the recommendation of the Paris Commission on the prevention of pollution from land-based sources that contracting parties should take account of the best available technology at nuclear reprocessing plants, in order to minimise radioactive discharges to the marine environment. The Radioactive Waste Management Advisory Committee have confirmed that, in their view, this programme take full account of all the scientific evidence, and is consistent with the United Kingdom's policy objectives for radioactive waste management, particularly the objective of reducing discharges to the lowest level reasonably practicable. The estimated annual radiation dose to the small critical group of people eating large amounts of fish and shellfish will be reduced to well below 10 per cent. of the limit recommended by the International Commission on Radiological Protection, as compared with 54 per cent. in 1982.

The two authorising departments plan to review the authorisation every three years, in line with a recommendation in the Black Report. For the purposes of such reviews, they will draw upon the results from an expanded programme of environmental monitoring they have now required BNFL to carry out as from January 1985, as well as their own check monitoring and relevant research. They will also take full account of advice on the health aspects of discharges, and my right honourable friend the Minister for Health is considering, in the light of the Black Report, how such advice can be best provided.