Development and validation of NECP-SARAX: An advanced neutron analysis code system for accelerator-driven subcritical systems

An accelerator-Driven Subcritical System (ADS) is a facility that utilizes high-energy spallation neutrons to transmute minor actinide nuclides and long-lived fission products, supporting the “partitioning and transmutation” strategy. However, the energy of spallation neutrons can reach hundreds of megaelectron volts, which represents a huge challenge to the deterministic neutron transport methods. To address this challenge, NECP-SARAX, an advanced neutron analysis code system, has been developed by the Nuclear Engineering Computational Physics Laboratory, Xi'an Jiaotong University. To apply NECP-SARAX code in the ADS, the influence of high-energy spallation neutrons on the system was evaluated as the first step. Next, SARAXLIB-HE, a high-energy neutron database, was established based on high-energy evaluation databases JENDL4.0-HE, JENDL-HE-2007, and IAEA-ADS-HE. To address neutron leakage and the impact of external sources, the NECP-SARAX code has been enhanced by incorporating a fixed source transport solver for fission materials during the process of generating few-group cross-sections. Finally, verifications of assembly and reactor benchmarks demonstrated that the SARALIB_HE database and the SARAX code are suitable for calculating and analyzing the ADS.