§ Mr. Dempseyasked the Secretary of State for Energy if he will make a statement about the recent leak of radioactivity on the Windscale site.
§ Mr. BennBNFL is constructing a new silo at Windscale for the storage of high-activity solid waste, comprising mainly the cladding from irradiated fuel elements. On 10th October 1976 a routine survey of the completed excavation for this revealed significant radiation levels in one corner of the excavation. These levels were high enough to require strict control of access to the excavation. They had not been present during the actual digging of the excavation. The source of the radioactive contamination was not identified and a more detailed survey was carried out on 17th October 1976.
This survey confirmed the presence of contamination, and British Nuclear Fuels Limited started investigations to determine the location and magnitude of the source. It informed the Nuclear Installations Inspectorate.
The Inspectorate discussed the situation on site with British Nuclear Fuels Limited, and has continued to monitor the progress of the investigations. These have involved further excavations and the drilling of boreholes.
The results of the investigations to date, first reported to me on 8th December, suggest that the contamination arises from a seepage of water some 311W 15 ft. below the ground through the concrete wall of an old silo in which is stored high-activity waste, principally the cladding from irradiated Magnox fuel. This waste is stored under water. This silo extends 20 ft. below ground and the part in question is of single walled construction, in contrast to an extension to it and new silos which are double-walled. There is no evidence of contamination from this leak reaching ground water, nor has the leak caused any contamination of surface water.
BNFL is urgently doing further work positively to identify the source and then to establish, with the Inspectorate, remedial action. The work is being carried out under full radiation protection supervision.
There has been no radiation exposure of any workers above permitted limits. There is no contamination outside the Windscale site and, therefore, no hazard to members of the public.
The Inspectorate has agreed that work on construction of the new silo may be resumed, since it is unlikely to impede the investigation and remedial work or to cause radiation hazards to workers. The Inspectorate is continuing to monitor the work. I shall report again to the House in the light of further advice from the Inspectorate as the work proceeds.