“The NECP-SARAX system developed by the Nuclear Engineering Computational Physics Laboratory of Xi'an Jiaotong University has shown excellent performance in the analysis of physical characteristics of fast reactor cores. Regarding the accuracy of the TULIP program in the calculation and analysis of fast spectrum problems, 147 critical experimental devices were selected for calculation and analysis. It was found that for experimental devices with thick reflection layers, the deviation between the calculated keff by the TULIP program and the calculated value by the Monte Carlo program exceeded 10-2. By optimizing the resonance calculation strategy and non resonance region calculation method of the TULIP program, the improved program has good computational and analytical capabilities for fast spectrum systems.”