The development of the combined fission matrix method in small advanced reactor design and optimization

Abstract

The Monte Carlo neutron transport method is widely used in small advanced reactor core designs and optimizations but with a high computational cost. As an efficient and accurate neutron transport method, the combined fission matrix method is promising in small reactor design and optimization. However, it cannot well predict the strong reflector impact on the fission matrix in small reactors. A predictor–corrector correction ratio method is proposed in this work to solve the problem. The method will be validated in the Holos and Simons transportable small reactors. Compared to the Monte Carlo result, the combined fission matrix method has a 36 pcm keff error with 1.7% 2D RMSE in the Holos core and 9 pcm keff error with 0.3% 2D RMSE in the Simons core. With a similar accuracy, the combined fission matrix method is much faster than the Monte Carlo method.