Optimization of energy-group structure for LWR high-fidelity neutronics calculation based on the contributon theory

ABSTRACT

Deterministic high-fidelity neutronics calculation is to solve the neutron transport equation using the multi-group (MG) nuclear data libraries. The energy-group structure (ES) in MG nuclear data libraries has a significant impact on the precision and efficiency of neutronics calculation. Therefore, to meet the requirement of high precision and efficiency for high-fidelity neutronics calculation, the contributon theory is adopted to select the optimal ESs for the high-fidelity neutronics code NECP-X which is developed by Nuclear Engineering Computational Physics (NECP) lab. at Xi’an Jiaotong University (XJTU). By combining the contributon theory with the exhaustive searching method, the optimal ESs can be selected effectively. Two optimal ESs named NECP-69 and NECP-47 are obtained and the nuclear data processing code NECP-Atlas developed by NECP lab. is utilized to generate the corresponding MG nuclear data libraries for NECP-X. The neutronics parameters of the MOX pin cell problems and the VERA benchmarks are evaluated. The numerical results show that more precise neutronics parameters are obtained based on the optimal ESs compared with those based on the conventional WIMS-69 and HELIOS-47 for NECP-X.