Equipment Qualification in the United Kingdom for the Sizewell "b" Pressurized Water Reactor

Sizewell "B" is the first in what is intended to be a series of Pressurised Water Reactors (PWR) in the United Kingdom (UK). Having been based upon a standardized US design, it was subjected to EQ requirements of IEEE Standards 627-1980, 323-1983, 344-1975 and ancilliary standards such as IEEE 382-1985, as interpreted by the Central Electricity Generating Board (CEGB) in their attachment specifications for environmental and seismic qualification. The same requirements for test sequence will apply in the UK as in the US, with a few modifications. Thermal aging must be performed in harsh environments, but when possible maintenance and surveillance will substitute for a conventional qualified life in mild environments. One reason for the CEGB\´s confidence in this approach is their long-standing practice of "type approval" of electrical and I&C equipment on all their power stations. "Type approval" is basically a sequence of testing to determine the equipment\´s reliability under normal operating and maintenance conditions. Radiation aging differs in that the design basis fault (DBF) source terms result in doses and dose rates considerably less than those required for a similar design plant in the US. Seismic qualification is being performed to the requirements of IEEE Standard 344-1975 with an all UK sites required response spectra. In order to address some specific concerns of the regulatory agency, a ground acceleration of 0.4 g is being employed. Harsh environment testing addresses margin by the use of two peak transients rather than increased temperature above the required envelope.