Research on In-Core Reactivity Control Method and Neutron Characteristic Analysis of a Space Gas-Cooled Reactor

Abstract

Compared with the conventional power system, the space nuclear reactor power system can provide a more stable and longer-life electricity supply, which can better meet the requirements of deep space exploration. For space gas-cooled reactors, the impact of the submerged accidents after a launch abort situation must be considered. In such an accident, the core void is filled with seawater and wet sand, the neutron spectrum in the reactor is thermalized, and the reactivity increases significantly and probably making the reactor supercritical. In this paper, the research focuses on a novel control system named the control ring. Two different neutron-absorption materials are doped in the control ring, and the reactivity control effect of the control ring in submerged accidents is analyzed with different enrichments of fuel. Also, the burnup and neutron spectrum of these two materials are also studied. The result shows that the performance of the reactivity control effect of gadolinium in the submerged accidents is equal to boron-10, and the control effect of the control drums will slightly increase when gadolinium is doped in the control ring. In addition, the reactivity penalty of gadolinium is smaller than boron-10. These results can provide a reference for the design of space gas-cooled nuclear reactors.