Development Of Cfd-Based High-Energy Line Break Evaluation Methodology And Its Application In The Evaluation Of Supersonic Jet Impingement Load Characteristics

Recently, the U.S. Nuclear Regulatory Commission indicated the non-conservativeness of ANSI/ANS 58.2, which is a technical standard for evaluating the jet impingement load owing to the high-energy line break accident in a nuclear power plant. Therefore, it is necessary to develop a new methodology that can accurately evaluate the characteristics of jet impingement load caused by a supersonic steam jet. In this study, a numerical analysis methodology for evaluating this load was developed and verified. In addition, the conservativeness of the ANSI jet model was investigated using the developed methodology. The results showed that the ANSI jet model could not sufficiently consider the physical behavior of the under-expanded steam jet and predicted a lower jet impingement load than the numerical analysis results at certain conditions. Thus, it is necessary to improve the jet impingement load evaluation model or introduce a new evaluation technique.