Optimized Designs for Control Rod Absorbers with a High-Fidelity Simulation Method Implemented in the Rmc Code

Abstract

A high-fidelity simulation method of the control rod absorbers is implemented in the Monte Carlo code RMC. For rare-earth absorbers and B4C which have been widely researched, detailed calculations and analyses are conducted for neutronic and depletion characteristics. Using this method, three kinds of optimized control rod absorbers are proposed with higher reactivity worth and favorable burnup stability. In these new designs, the composite absorbers possess higher reactivity worth and only average 20% reactivity loss at the end of cycle (EOC). The enriched absorbers have better neutron absorbing capacity and more stable radiation resistence, and the reactivity loss of enriched B4C reduces from 90% to only 7.42% at EOC. For mixed absorbers, the best properties are found for the Dy and B4C mixture when the proportion of Dy is about 60%. The coupling of ZrH2 and Hf achieves a better control efficiency, but unfortunately the reactivity loss increases at EOC.

Keywords: high-fidelity simulation, control rod absorbers, optimized designs, RMC