基于蒙特卡洛程序的快堆少群截面制作方法研究

Research on Few Group Cross-Section Generation Method For Fast Reactor Based on Monte Carlo Code

为了提高快堆中子学分析精度,解决传统确定论方法制作快堆少群截面面临的复杂共振问题,基于组件均匀化-堆芯输运计算两步法,从各向异性散射、能群结构、泄漏修正等方面,开展了采用蒙特卡洛程序制作堆芯输运计算所需的组件均匀化少群截面的方法研究。数值结果表明:采用蒙特卡洛程序制作快堆少群截面,可以很好地处理中等质量核素的共振效应;采用1阶散射截面或者输运修正后的少群截面可以有效考虑各向异性散射的影响;少群截面的能群数目减小会导致堆芯有效增殖因子(k_(eff))减小;泄漏修正会导致堆芯k_(eff)增大。采用蒙特卡洛程序制作快堆少群截面,堆芯输运得到的k_(eff)偏差小于100pcm(1pcm=10^(-5)),功率分布偏差小于2%。

In order to improve the accuracy of neutronics analysis for fast reactors and solve the complex resonance problem faced by traditional deterministic method in making few group cross-sections of fast reactors,this paper,based on the two-step method of assembly homogenization-core transport calculation,studies the method of assembly homogenized few group cross-section by using the Monte Carlo code from the aspects of anisotropic scattering,energy group structure and leakage correction.The numerical results show that the resonance effect of medium-mass nuclides can be well treated in the fast reactor few group cross-section generation based on the Monte Carlo code;the effects of anisotropic scattering can be effectively considered with 1-order scattering cross-section or transport modified few group section.Core effective multiplication factor(k_(eff))may decrease due to the decrease in the number of energy groups of few group cross-section;core k_(eff)may increase due to the leakage correction.When Monte Carlo code is used in few group cross-sections generation of fast reactor,the k_(eff)deviation of core transport is less than 100 pcm(1pcm=10^(−5)),and the power distribution deviation is less than 2%.