Seismic Test Results of the Main Steam Isolation Valve for Japanese Boiling Water Reactor Nuclear Power Plants (Part 2)

Abstract

Abstract The functional requirements of Main Steam Isolation Valves (MSIVs) provided in the Boiling Water Reactor (BWR) nuclear power plants in Japan have been previously evaluated via seismic tests and so forth. However, since the response acceleration has increased in line with a recent reassessment of standard earthquake ground motions, it is necessary to evaluate seismic operability with respect to high acceleration. In addition, from the viewpoint of equipment fragility in seismic PRA, it is necessary to determine practical seismic operability limits. We already confirmed that MSIV has capable of maintaining correct function for response accelerations up to 15 × 9.8 m/s2 in all directions (see Ref.[1]) using a resonant shaking table in the Central Research Institute of the Electric Power Industry (CRIEPI) (see Ref.[2]), which is capable of seismic tests at acceleration levels previously unachievable. Additional seismic tests for a MSIV were conducted and we obtained results confirming that validated seismic operability was possible even at response accelerations as high as 20 × 9.8 m/s2. The seismic operability results obtained for this MSIV will be applied to a fragility analysis of seismic PRA.