Large LOCA-earthquake event combination probability assessment - Load Combination Program Project I summary report
This report summarizes work performed to establish a technical basis for the NRC to use in reassessing its requirement that earthquake and large loss-of-coolant accident (LOCA) loads be combined in the design of nucelar power plants. A systematic probabilistic approach is used to treat the random nature of earthquake and transient loading to estimate the probability of large LOCAs that are directly and indirectly induced by earthquakes. A large LOCA is defined in this report as a double-ended guillotine break of the primary reactor coolant loop piping (the hot leg, cold leg, and crossover) of a pressurized water reactor (PWR). Unit 1 of the Zion Nuclear Power Plant, a four-loop PWR-1, is used for this study. To estimate the probability of a large LOCA directly induced by earthquakes, only fatigue crack growth resulting from the combined effects of thermal, pressure, seismic, and other cyclic loads is considered. Fatigue crack growth is simulated with a deterministic fracture mechanics model that incorporates stochastic inputs of initial crack size distribution, material properties, stress histories, and leak detection probability. Results of the simulation indicate that the probability of a double-ended guillotine break, either with or without an earthquake, is very small (on the order of 10/sup -12/). The probability of a leak was found to be several orders of magnitude greater than that of a complete pipe rupture.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5336554
- Report Number(s):
- UCID-18694; ON: TI85016669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
EARTHQUAKES
ENRICHED URANIUM REACTORS
FAILURES
FRACTURE MECHANICS
LEAKS
LOSS OF COOLANT
MECHANICS
NUCLEAR FACILITIES
NUCLEAR POWER PLANTS
PIPES
POWER PLANTS
POWER REACTORS
PWR TYPE REACTORS
REACTOR ACCIDENTS
REACTORS
SEISMIC EFFECTS
SEISMIC EVENTS
STRESS ANALYSIS
THERMAL POWER PLANTS
THERMAL REACTORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
ZION-1 REACTOR