Probability of pipe failure in the reactor coolant loops of Westinghouse PWR Plants. Volume 1. Summary report
As part of its reevaluation of the double-ended guillotine break (DEGB) of reactor coolant loop piping as a design basis event for nuclear power plants, the US Nuclear Regulatory Commission (NRC) contracted with the Lawrence Livermore National Laboratory (LLNL) to estimate the probability of occurrence probability. This report describes a probabilistic evaluation of reactor coolant loop piping in PWR plants having nuclear steam supply systems designed by Westinghouse. Two causes of pipe break were considered: pipe fracture due to the growth of cracks at welded joints (''direct'' DEGB), and pipe rupture indirectly caused by failure of component supports due to an earthquake (''indirect'' DEGB). The probability of direct DEGB was estimated using a probabilistic fracture mechanics model. The probability of indirect DEGB was estimated by estimating support fragility and then convolving fragility and seismic hazard. The results of this study indicate that the probability of a DEGB from either cause is very low for reactor coolant loop piping in these plants, and that NRC should therefore consider eliminating DEGB as a design basis event in favor of more realistic criteria. 17 refs., 15 figs., 11 tabs.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5655355
- Report Number(s):
- NUREG/CR-3660-Vol.1; UCID-19988-Vol.1; ON: TI85015267
- Country of Publication:
- United States
- Language:
- English
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21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
PWR TYPE REACTORS
LOSS OF COOLANT
PRIMARY COOLANT CIRCUITS
COMPUTER CALCULATIONS
EARTHQUAKES
FATIGUE
LEAKS
PIPES
PROBABILISTIC ESTIMATION
PROBABILITY
REACTOR SAFETY
RISK ASSESSMENT
SEISMIC EFFECTS
SENSITIVITY ANALYSIS
STAINLESS STEEL-316
WELDED JOINTS
ACCIDENTS
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
COOLING SYSTEMS
CORROSION RESISTANT ALLOYS
ENERGY SYSTEMS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
MATERIALS
MECHANICAL PROPERTIES
MOLYBDENUM ALLOYS
NICKEL ALLOYS
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
REACTORS
SAFETY
SEISMIC EVENTS
STAINLESS STEELS
STEELS
WATER COOLED REACTORS
WATER MODERATED REACTORS
220900* - Nuclear Reactor Technology- Reactor Safety
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Light-Water Moderated
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