Host: The Japan Society of Mechanical Engineers
Name : The 30th International Conference on Nuclear Engineering (ICONE30)
Date : May 21, 2023 - May 26, 2023
The present study is relating the reactor power control using a system for removing fission product gases from a molten salt fast reactor. Because molten salt reactors are equipped with a fission gas removal system, such as Xe gas, controlling the reactor power using this system has been studied. In this system, the Xe gas is removed by injecting helium gas bubbles into the molten fuel salt. When the void fraction of helium gas increases by 1%, the reactivity of approximately -380 pcm δk/k is introduced. Transient behaviors under a single-phase flow are analyzed by RELAP5-3D code, and FLUENT code with a user defined function which incorporates the point kinetics model, assuming reactivity insertion. To verify that the single-phase flow calculations make sense, we are also calculating two-phase flow using FLUENT. As a result, it is conceivable that the reactor could be controlled by increasing or decreasing the void fraction, and the reactor is tripped if a void fraction increases by more than 4%. At reactor start-up, operation starts with a void fraction of about 4%, and by increasing the flow rate of molten fuel salt resulting in reducing the void fraction to about 0.4%, the reactor power can be increased to the rated power.
