Failure probability estimate of Type 304 stainless steel piping
- Westinghouse Savannah River Co., Aiken, SC (USA)
The primary source of in-service degradation of the SRS production reactor process water piping is intergranular stress corrosion cracking (IGSCC). IGSCC has occurred in a limited number of weld heat affected zones, areas known to be susceptible to IGSCC. A model has been developed to combine crack growth rates, crack size distributions, in-service examination reliability estimates and other considerations to estimate the pipe large-break frequency. This frequency estimates the probability that an IGSCC crack will initiate, escape detection by ultrasonic (UT) examination, and grow to instability prior to extending through-wall and being detected by the sensitive leak detection system. These events are combined as the product of four factors: (1) the probability that a given weld heat affected zone contains IGSCC, (2) the conditional probability, given the presence of IGSCC, that the cracking will escape detection during UT examination, (3) the conditional probability, given a crack escapes detection by UT, that it will not grow through-wall and be detected by leakage, and (4) the conditional probability, given a crack is not detected by leakage, that it grows to instability prior to the next UT exam. These four factors estimate the occurrence of several conditions that must coexist in order for a crack to lead to a large break of the process water piping. When evaluated for the SRS production reactors, they produce an extremely low break frequency. The objective of this paper is to present the assumptions, methodology, results and conclusions of a probabilistic evaluation for the direct failure of the primary coolant piping resulting from normal operation and seismic loads. This evaluation was performed to support the ongoing PRA effort and to complement deterministic analyses addressing the credibility of a double-ended guillotine break.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (USA)
- Sponsoring Organization:
- DOE/DP
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 5619261
- Report Number(s):
- DP-MS-89-83; CONF-8910192--8; ON: DE90000659
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220700* -- Nuclear Reactor Technology-- Plutonium & Isotope Production Reactors
36 MATERIALS SCIENCE
360103 -- Metals & Alloys-- Mechanical Properties
360105 -- Metals & Alloys-- Corrosion & Erosion
ACCIDENTS
ALLOYS
AUSTENITIC STEELS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CORROSION
CORROSION RESISTANT ALLOYS
CRACK PROPAGATION
CRACKS
HEAT AFFECTED ZONE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH ALLOY STEELS
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
LOSS OF COOLANT
MATERIALS
NATIONAL ORGANIZATIONS
NICKEL ALLOYS
PIPES
PROBABILITY
PRODUCTION REACTORS
REACTOR ACCIDENTS
REACTORS
SAVANNAH RIVER PLANT
SEISMIC EFFECTS
STAINLESS STEEL-304
STAINLESS STEELS
STEEL-CR19NI10
STEELS
STRESS CORROSION
US AEC
US DOE
US ERDA
US ORGANIZATIONS
WELDED JOINTS
ZONES