Research on Source Term Calculation of Corrosion Products under Fusion Reactor Pulse Condition

活化腐蚀产物是聚变堆的主要源项之一，由于聚变堆的中子通量密度是按短时脉冲产生的，使得进行长周期的源项分析时需要计算大量的脉冲，因此需要研究脉冲的等效处理方法以提高计算效率。目前可用的脉冲等效处理方法主要有稳态(SS)方法、等效稳态(ESS)方法和连续脉冲(CP)方法。本文在活化腐蚀产物源项分析程序CATE3.0的基础上，增加了脉冲等效处理功能，并对中国聚变工程实验堆(China Fusion Engineering Test Reactor, CFETR)的包层水冷回路进行了建模仿真。分别采用SS、ESS和CP三种方法对CFETR活化腐蚀产物源项进行计算，并以精确脉冲建模(EP)方法的计算结果为基准进行比较和分析。结果表明：在单级脉冲运行下，前期使用ESS方法近似处理的CP方法(CP(ESS))计算精度最高，半衰期为102 s~104 s的核素，当末尾的脉冲时间在10~15个左右半衰期后就可以趋于稳定；在多级脉冲一级等效下，CP(ESS)方法同样适用，并且末尾保留少量脉冲时，计算结果就能达到较高的精度；此外，脉冲时间越短，脉冲等效处理方法的计算时间节省效益越显著。Activated corrosion products are one of the main source terms of fusion reactor. Because the neutron flux density of fusion reactor is generated by short-time pulse, a large number of pulses are involved in the long-period source term analysis. So it is necessary to study the equivalent treatment method of pulses to improve the calculation efficiency. At present, the available pulse equivalent treatment methods mainly include steady state (SS) method, equivalent steady state (ESS) method and continuous pulse (CP) method. In this paper, on the basis of the activated corrosion products source term analysis program CATE3.0, the pulse equivalent treatment function was added, and simulated the blanket water cooling loop of the China Fusion Engineering Test Reactor (CFETR). SS, ESS and CP methods were used to calculate the source terms of CFETR activated corrosion products, and the calculation results of exact pulse (EP) modeling method were used as the basis for systematic comparison and analysis. The results show that in the single-level pulse operation, the CP method, which is approximated by ESS method in the early stage (CP(ESS)), has higher calculation accuracy. Nuclides with a half-life period of 102 s~104 s can stabilize when the final pulse time is about 10~15 half-life period. In the multistage pulse first-level equivalence, CP(ESS) method is also applicable, and it is highly accurate when a small number of pulses are retained at the end. In addition, the shorter the pulse time, the more significant the computational time saving benefit of pulse equivalent treatment methods.