Evaluation of reaction jet behavior caused by sodium-water reaction in steam generator of sodium-cooled fast reactor using particle method

東ヶ崎 駿*; Jang, S.*; 小坂 亘  ; 内堀 昭寛 ; 岡野 靖

Togasaki, Shun*; Jang, S.*; Kosaka, Wataru; Uchibori, Akihiro; Okano, Yasushi

In the steam generator of a sodium-cooled fast reactor, if a heat transfer tube fails and high-pressure water/steam leaks into the sodium, a rapid chemical reaction called the sodium-water reaction occurs. The high-temperature, high-velocity, and corrosive reaction jets formed by this reaction bring thermal and mechanical loads on other tubes, causing secondary ruptures of neighbouring tubes. Thus, it is important to evaluate the behaviour of the reaction jet after a leak has occurred in the safety assessment of sodium-cooled fast reactor plants. Numerical solutions to evaluate the effects of the propagation of tube failures have attracted attention, and a computer program called SERAPHIM has been developed as one of these solutions. Although SERAPHIM can evaluate reaction jet behavior in detail, it requires high computational performance and time. Significantly, an analysis code based on the particle method approach has been developed by the Japan Atomic Energy Agency. This code is a breakthrough in our field, aiming to lower computational costs and enhance our understanding of the reaction jet behavior. The vapor jet from the broken hole in the heat transfer tube is simulated by the particle method, and the interaction of the jet with the tube and sodium is modeled as a force acting on the particles. This approach significantly reduces computational cost while providing accurate results, a promising advancement in our research. In this study, we upgraded the particle method code by improving the physical models that make up this code and introducing new models. As a result, the particle method code calculated the maximum temperatures similar to the results obtained with the SERAPHIM in a short computation time. The particle method code has the potential to become one of the fastest methods for parameter analysis in complex systems.