Consequences of expansion joint bellows rupture
Expansion joints are used in piping systems to accommodate pipe deflections during service and to facilitate fitup. Typically, the expansion joint bellows is the thinnest part of the pressure boundary, bellows rupture frequencies are typically several orders of magnitude higher than pipe rupture frequencies. This paper reviews an effort to estimate the flow rates associated with bellows rupture. The Level I PRA (probabilistic risk assessment) for the Savannah River Site production reactors made the bounding assumption that bellows rupture would produce the maximum possible leakage - that of a double-ended guillotine break (DEGB). This assumption resulted in predictions of flooding of the reactor building with a high conditional probability that a Loss of Pumping Accident and core melting would follow. This paper describes analyses that were performed to develop a realistic break area and leak rate resulting from bellows rupture and therefore reduce the impact that bellows rupture can have on the estimated total core melt frequency. In the event of a 360 degree circumferential break of the bellows the resulting two sections will separate to the point where the force from the internal pressure acting to push the bellows open is just balanced by the spring force of the bellows itself. For the bellows addressed in this analysis, the equilibrium separation distance is 0.7 inches with normal pump lineup. The opening area is influenced by any initial compression or extension due to installation alignment, and by any operational displacements such as thermal expansion of the adjoining pipe. The influence of such factors is considered and the impact on the flooding rate and, hence, core melt frequency is reviewed.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 6862348
- Report Number(s):
- WSRC-MS-92-265; CONF-930352-3; ON: DE93002173
- Resource Relation:
- Conference: 2. international conference on nuclear engineering, San Francisco, CA (United States), 21-24 Mar 1993
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BELLOWS
RUPTURES
EXPANSION JOINTS
LOSS OF COOLANT
PROBABILISTIC ESTIMATION
REACTOR COOLING SYSTEMS
SPECIAL PRODUCTION REACTORS
ALIGNMENT
FLOW RATE
PIPES
REACTOR SAFETY
THERMAL EXPANSION
ACCIDENTS
COOLING SYSTEMS
EXPANSION
FAILURES
JOINTS
MECHANICAL STRUCTURES
PRODUCTION REACTORS
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTORS
SAFETY
220900* - Nuclear Reactor Technology- Reactor Safety
220600 - Nuclear Reactor Technology- Research
Test & Experimental Reactors