Evaluation of JNES Equipment Fragility Tests for Use in Seismic Probabilistic Risk Assessments for U.S. Nuclear Power Plants (NUREG/CR-7040, BNL-NUREG-94629-2011)

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Publication Information

Manuscript Completed: January 2011
Date Published: April 2011

Prepared by:
R. Kennedy¹
J. Nie and C. Hofmayer²

¹RPK Structural Mechanics Consulting
28625 Mountain Meadow Road
Escondido, CA 92026

² Brookhaven National Laboratory
P.O. Box 5000
Upton, NY 11973-5000

S. Ali, NRC Project Manager

NRC Job Codes N6076 and N6998

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

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Abstract

The Japan Nuclear Energy Safety Organization (JNES) is conducting a multi-year equipment fragility test program to obtain realistic equipment fragility capacities for use in the seismic probabilistic risk assessments (SPRAs) of nuclear power plants (NPPs) in Japan. This test program started in 2002 and is planned to continue until 2012. The purpose of this test program is to improve the quality of the seismic fragility capacity database by determining realistic equipment fragility capacities from full-scale shaking table tests, and consequently to allow more accurate SPRAs to be performed to quantify the risk of NPPs during beyond-design-basis earthquakes. This test program reflects a philosophical shift from the design-proving test in the past that was intended to demonstrate the success of equipment under design basis or slightly larger earthquakes, to the current fragility test that determines the (ultimate) seismic capacity under beyond-design-basis earthquakes. This program consists of the test of a series of safety significant equipment, which are scheduled in two phases. Phase I includes large horizontal shaft pumps, large vertical shaft pumps, electrical panels, and control rod insertion capability and Phase II includes fans, valves, tanks, support structures, and overhead cranes.

As part of collaborative efforts between the United States and Japan on seismic issues, the U.S. Nuclear Regulatory Commission (NRC) and Brookhaven National Laboratory (BNL) participated in this program by evaluating the results of the JNES equipment fragility tests. The goal of this research effort was to compare the JNES fragility results with the fragility data typically used in current U.S. SPRAs and assess the impact that the new test results may have on current SPRAs and how this data can be utilized for future SPRAs. The JNES fragility results are also useful for seismic margin analyses (SMAs), which are important in design certification (DC) or combined license (COL) applications because of the lack of full SPRAs at the DC or COL stage. This report summarizes the BNL evaluation of the JNES equipment fragility test data and provides insights on the applicability and application of this data in U.S. SPRA practices.