Assessment of the impact of degraded shear wall stiffnesses on seismic plant risk and seismic design loads

Technical Report · Tue Feb 01 04:00:00 EST 1994

DOI:https://doi.org/10.2172/10134778· OSTI ID:10134778

Klamerus, E W; Bohn, M P ^[1]; Johnson, J J; Asfura, A P; Doyle, D J ^[2]

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1. Sandia National Labs., Albuquerque, NM (United States)
2. EQE Engineering, Inc., San Francisco, CA (United States)

Test results sponsored by the USNRC have shown that reinforced shear wall (Seismic Category I) structures exhibit stiffnesses and natural frequencies which are smaller than those calculated in the design process. The USNRC has sponsored Sandia National Labs to perform an evaluation of the effects of the reduced frequencies on several existing seismic PRAs in order to determine the seismic risk implications inherent in these test results. This report presents the results for the re-evaluation of the seismic risk for three nuclear power plants: the Peach Bottom Atomic Power Station, the Zion Nuclear Power Plant, and Arkansas Nuclear One -- Unit 1 (ANO-1). Increases in core damage frequencies for seismic initiated events at Peach Bottom were 25 to 30 percent (depending on whether LLNL or EPRI hazard curves were used). At the ANO-1 site, the corresponding increases in plant risk were 10 percent (for each set of hazard curves). Finally, at Zion, there was essentially no change in the computed core damage frequency when the reduction in shear wall stiffness was included. In addition, an evaluation of deterministic ``design-like`` structural dynamic calculations with and without the shear stiffness reductions was made. Deterministic loads calculated for these two cases typically increased on the order of 10 to 20 percent for the affected structures.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering; Sandia National Labs., Albuquerque, NM (United States); EQE Engineering, Inc., San Francisco, CA (United States)
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 10134778
• Report Number(s): NUREG/CR--5407; SAND--93-0234; ON: TI94008643; BR: GB0103012
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
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22 GENERAL STUDIES OF NUCLEAR REACTORS
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ARKANSAS-1 REACTOR
COMPUTER CALCULATIONS
DYNAMIC LOADS
MECHANICAL STRUCTURES
PEACH BOTTOM-1 REACTOR
PEACH BOTTOM-2 REACTOR
PEACH BOTTOM-3 REACTOR
POWER REACTORS
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GRAPHITE MODERATED
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LIGHT-WATER MODERATED
BOILING WATER COOLED
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REACTOR SAFETY
RISK ASSESSMENT
SEISMIC EFFECTS
WALLS
ZION-1 REACTOR
ZION-2 REACTOR