核数据引起的研究堆有效增殖因子计算不确定度量化

Quantification of calculated effective multiplication factor uncertainty caused by nuclear data in research reactor

为了深入研究核数据不确定度对JRR-3M研究堆有效增殖因子计算的影响,建立了一套基于蒙特卡罗法的核数据不确定度量化流程。具体方法为:使用核数据扰动软件SANDY扰动目标核素的重要反应道生成扰动文件,再通过核数据加工软件NJOY对扰动文件进行处理,最终利用核反应堆物理模拟软件OpenMC进行蒙特卡罗模拟。针对JRR-3M研究堆的控制棒全插、反应堆临界、控制棒全拔三种运行工况,对多个关键核素(如235U、238U、Hf等)的核数据不确定度给有效增殖因子计算带来的影响进行了详细分析。研究结果表明,177Hf、235U、1H、27Al的核数据不确定度对JRR-3M有效增殖因子具有显著影响。临界、控制棒全插和控制棒全提这3种工况下,核数据不确定引起的有效增殖因子总不确定度分别为660.8×10^(-5)、588.5×10^(-5)、708.4×10^(-5)。在各个工况下,235U的次级粒子能量分布的影响都是最大的。研究发现,对以铪为主要组成材料的控制棒内,只有177Hf的核数据不确定度起主要影响。

To delve into the impact of nuclear data uncertainty on the effective multiplication factor calculation for the JRR-3M research reactor,this study established a nuclear data uncertainty quantification process based on SANDY.The specific methodology involved perturbing important reaction pathways of the target nuclides with SANDY to generate perturbation files,processing these files with NJOY,and ultimately utilizing OpenMC for Monte Carlo simulations.The influence on the effective multiplication factor due to several key nuclides(such as 235U,238U,Hf,etc.)data uncertainty was calculated and analysed for three operational conditions of the JRR-3M research reactor.For critical,control rods fully inserted and control rods fully withdrawn conditions,total effective multiplication factor uncertainties are 660.8×10^(-5),588.5×10^(-5) and 708.4×10^(-5),respectively.In all operational conditions,the impact of the fission release neutron energy distribution of 235U is the most notable.The study reveals that within hafnium control rods only the nuclear data uncertainty of 177Hf plays a major role.