asked the Secretary of State for Energy when he expects the Health and Safety Executive to publish a report on the seepage of contaminated water from a storage silo at Windscale found in October 1976.
The Health and Safety Executive (HSE) has today published a full report on this incident. I have arranged for copies to be placed in the Library of the House.The report describes the very thorough review carried out jointly by the nuclear installations inspectorate (NII) and radiochemical inspectorate (RCI). British Nuclear Fuels Limited (BNFL) has cooperated fully with the inspectorates and has conducted much supportive research into possible remedial actions and into the radiological effects of the leak.The report's conclusion is that the leak does not constitute a hazard to the safety of workers at the site; to the environment beyond the immediate vicinity of the leak; or to the public. The greater part of this activity which has leaked from the silo is retained in the soil close to the silo and above the water table. It is estimated that nuclides not absorbed by soil would take some years to migrate to the site boundary, during which time their radioactivity would decay to a negligible level. In view of this, the report concludes that the primary objective (though it will take some time to achieve) should be to empty the silo and dispose of its contents safely rather than attempt to seal the leak with the silo full, which, besides being hazardous and of uncertain effectiveness with present techniques, could prejudice the possibility of emptying the silo later. The company has accordingly been required to develop the necessary techniques for emptying the silo.However, HSE also considers it important that contingency plans should be available to seal the leak or to stop the spread of activity should the monitoring of the area reveal that the rate of leakage is increasing, or that activity is spreading away from the immediate vicinity of the silo.The Company has, therefore, been required to continue to monitor activity and assess the environmental impact of potential activity; and to develop contingency plans to seal the leak or erect a curtain wall outside the silo. Development work on a means of sealing the silo will include work on a means of sealing from the inside which will not prejudice the retrieval of material from it. If a practicable technique is developed, it could be used to prevent further discharges from the silo pending its emptying.The report also notes that the silo no longer receives waste. The first extension, now in use, is of different construction, having cavity walls permitting for, and recovery of, any water leakage. A further extension, now under construction, has double containment of the base as well as cavity walls.