Neutronic Optimization of Thorium Molten Salt Reactor Moderated by Zirconium Hydride Rod

Zirconium hydride (ZrH) is a commonly used reactor moderator due to its high temperature resistance, irradiation damage resistance and slowing-down power. This study aims to optimize core physical design of a ZrH moderated molten salt reactor to realize the self-sustaining operation by thorium uranium conversion, and to have low MA production. MOC program was used to analyze the effects of different fuel salts on start-up and breeding performance. In order to improve the thorium uranium conversion performance, the core structure and the design of the moderator rods were optimized and analyzed. The results show that when the volume ratio of molten salt is between 0.5 and 0.9, the critical ²³³U concentration reduces to around 2%. The average thorium uranium conversion ratio (CR) of the ZrH moderated molten salt reactor with the fertile zone and the FLi fuel salt can reach 1.028 in 50 a. The design of the movable moderator rods in the reactor can achieve a self-sustaining operation for 38 a, and the production of MA at the end of life reduces about 43% and 8%, respectively, compared with the production of MA using FLi fuel salt and FLiBe fuel salt under the condition that the moderators don’t move, and lower than that of the graphite moderated molten salt reactor under the same power output.