Application of probabilistic fracture mechanics to the PTS issue
As a part of the NRC effort to obtain a resolution to the PWR PTS issue, a probabilistic approach has been applied that includes a probabilistic fracture-mechanics (PFM) analysis. The PFM analysis is performed with OCA-P, a computer code that performs thermal, stress and fracture-mechanics analyses and estimates the conditional probability of vessel failure, P(F/E), using Monte Carlo techniques. The stress intensity factor (K/sub I/) is calculated for two- and three-dimensional surface flaws using superposition techniques and influence coefficients. Importance-sampling techniques are used, as necessary, to limit to a reasonable value the number of vessels actually calculated. Analyses of three PWR plants indicate that (1) the critical initial flaw depth is very small (5 to 15 mm), (2) the benefit of warm prestressing and the role of crack arrest are transient dependent, (3) crack arrest does not occur for the dominant transients, and (4) the single largest uncertainty in the overall probabilistic analysis is the number of surface flaws per vessel. 30 refs., 6 figs., 4 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5531074
- Report Number(s):
- CONF-850679-2; ON: TI85014654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
210200* -- Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
COMPUTER CODES
COMPUTERIZED SIMULATION
CONTAINERS
FAILURE MODE ANALYSIS
FAILURES
FRACTURE MECHANICS
MECHANICS
O CODES
PRESSURE VESSELS
PROBABILITY
PWR TYPE REACTORS
REACTORS
SIMULATION
STRESS ANALYSIS
STRESSES
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
THERMAL STRESSES
WATER COOLED REACTORS
WATER MODERATED REACTORS