The CEGB aseismic piping research programmer

The paper presents the Central Electricity Generating Board Research and Development Programme for securing improvements in the aseismic design of piping systems for future U.K. PWR stations replicating Sizewell B. The initial thrust of the programme established in 1987 centered on providing the basis for justifying increases in the allowables permitted in ASME Section III Equation 9 Level D analysis. This aspect was addressed primarily through the EPRI/CEGB Exchange Agreement on Seismic Testing and Analysis. The UK work involved dynamic testing of straight pipes and attached components (Berkeley Nuclear Laboratories) complementary theoretical analysis (National Nuclear Corporation) and piping system tests at the HDRZ facility, FRG (the SHAM programme). A summary of the results of these activities is presented. ASME Equation 9 analysis involves stress indices: the current approach cites B indices, whereas proposed changes advocate either B or C indices in alternative approaches. There is a need to consider the development of more appropriate indices than either B or C and U.K. work in this area is described. In the longer term a Design by Rule approach is preferred. The paper concludes by exploring some of the envisaged requirements