Boiling Water Reactor Recirculation Line Break Acoustic Loads: A Bounding Approach

Recent industry communications have identified issues pertaining to incorrectly calculated recirculation line break acoustic loads or structural evaluations that need to include, but have previously excluded, the recirculation line break acoustic loads. Various organizations have studied the recirculation line break event and have developed methodologies to calculate the decompression loads caused by this event on various boiling water reactor internal components. In general, loads are calculated in a plant specific and operating condition specific manner. Once these loads are available then the necessary structural evaluations can be performed. With the various flexibility options that an operating boiling water reactor can be licensed for it can become difficult to know when the recirculation line break acoustic loads must be updated and subsequently, which structural evaluations must be updated as well. In this paper a simple extension of an existing, benchmarked, acoustic loads methodology is suggested in which a bounding set of input parameters is evaluated in order to predict acoustic loads that will bound all flexibility options that are currently implemented at operating plants. The objective of this approach is to save the utilities time and money by enabling a single iteration of loads calculation and structural analysis. This approach is shown to produce loads that are approximately a factor of 1.5 larger than those predicted using typical operating parameters.