Description of the approach to assuring nuclear installation safety reliability in the U.K. (Illustrated by reference to the proposed Sizewell PWR station)

A review is given of the standards, regulations and procedures produced and utilised in the U.K. for assuring nuclear installation safety reliability. It concentrates on those relevant to electricity power stations and is illustrated by the procedure applied to the proposed Sizewell B station. However, similar principles have been developed applying to nuclear reprocessing and waste management, and similar procedures are being applied. In the United Kingdom the Central Electricity Generating Board (CEGB) is responsible for the safety of its employees and the public from any nuclear hazards arising from its installations. The safety criteria and assessment procedures required by the CEGB are described in the paper. The safety requirements take into account the Safety Assessment Principles of the Nuclear Installations Inspectorate (NII) which are also discussed. The overall reliability requirements are discussed in detail with particular reference to protective systems. A brief description is presented of the degraded core accident analysis of the Sizewell ''B'' pressurized water reactor (PWR). This together with a presentation and discussion of the results of this probabilistic safety assessment was prepared for the Public Enquiry concerned with planning permission for the station. The frequency with which releases of activity would occur are shown to be considerably lower than required by the principles and regulations of the authorities concerned. 8 refs