Probability of Pipe Fracture in the Primary Coolant Loop of a PWR Plant. Volume 8: Pipe Fracture Indirectly Induced by an Earthquake

摘要

In this volume the probability that a double-ended guillotine break in the primary coolant loop of a pressurized water reactor occurs simultaneously with (and is indirectly caused by) a seismic event is considered. The pipe break is a consequence of a seismically initiated failure in a system other than the primary piping itself. Events studied that can lead to an indirectly induced pipe break include structural and mechanical failures, missile impact, pressure transients, jet impingement, fire, and explosion. Structural failures of the supports for the reactor pressure vessel, reactor coolant pump, and steam generator have the highest probability of causing a double-ended pipe break. Furthermore, it was found that structural failure of the containment dome and a failure of the reactor coolant pump flywheel have the highest potential for a missile-caused pipe break. Since structural failure proved to be a major factor, a model to estimate the probability of structural failure was developed; this model is based on the engineering factors of safety and seismic hazard. Preliminary results indicate that the probability of a double-ended pipe break indirectly caused by a seismic event during the plant life is on the order of 10 to the minus 9.