Burnup performance analysis for candidate materials of the LWR accident tolerant control rod

The accident tolerant fuel (ATF) is considered to be one of the most advanced concepts to improve the safety of light water reactors (LWRs). The accident tolerant control rod (ATCR) is a significant aspect in the ATF concept. The melting temperature of traditional LWR control rod (CR) materials, such as silver-indium-cadmium (AIC) alloy, is too low to endure the high temperature under several accident conditions. Consequently, varieties of candidate materials for control rod have been proposed in the previous researches because of the outstanding characters of high-temperature behavior, as well as reactivity worth, stability in coolant water and so on. In this paper, the burnup performance of the sesquioxides of the rare-earth elements (RE₂O₃) and the hafnia (Hf) are analyzed and compared to the traditional AIC control rod. Two parameters are chosen to reveal the burnup performance of the candidate control rod materials, the initial control rod reactivity worth and the stability of the control rod reactivity worth along with the assembly burnup. The candidate-material control rods and the AIC control rod are placed in the ATF assembly with the same conditions, and the assembly is depleted to sufficient burnup. Numerical results indicate that Eu₂O₃, Dy₂O₃, Sm₂O₃ and Hf are excellent ATCR materials compared to AIC.