Failure probability of PWR reactor coolant loop piping. [Double-ended guillotine break]
This paper describes the results of assessments performed on the PWR coolant loop piping of Westinghouse and Combustion Engineering plants. For direct double-ended guillotine break (DEGB), consideration was given to crack existence probability, initial crack size distribution, hydrostatic proof test, preservice inspection, leak detection probability, crack growth characteristics, and failure criteria based on the net section stress failure and tearing modulus stability concept. For indirect DEGB, fragilities of major component supports were estimated. The system level fragility was then calculated based on the Boolean expression involving these fragilities. Indirect DEGB due to seismic effects was calculated by convolving the system level fragility and the seismic hazard curve. The results indicate that the probability of occurrence of both direct and indirect DEGB is extremely small, thus, postulation of DEGB in design should be eliminated and replaced by more realistic criteria.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5186529
- Report Number(s):
- UCRL-86249; ON: DE84009540
- Country of Publication:
- United States
- Language:
- English
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21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
DESIGN BASIS ACCIDENTS
PROBABILITY
PWR TYPE REACTORS
BLOWDOWN
CRACKS
FAILURES
LEAKS
PIPES
PRIMARY COOLANT CIRCUITS
SEISMIC EFFECTS
ACCIDENTS
COOLING SYSTEMS
ENERGY SYSTEMS
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
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220900* - Nuclear Reactor Technology- Reactor Safety
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