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球床氟盐冷却高温反应堆作为第四代反应堆,选用2LiF-BeF2做冷却剂。2LiF-BeF2中含有微观吸收截面很大6Li核素,其摩尔含量会对冷却剂的温度反应性系数造成影响,因此研究6Li摩尔含量对冷却剂温度反应性系数的影响十分必要。本文以无限球床为计算模型,利用SCALE6(Standardized Computer Analyses for Licensing Evaluation)对不同6Li摩尔含量的冷却剂温度反应性系数进行研究。分析结果表明,当冷却剂中6Li摩尔含量占Li元素总量的0.005%时,冷却剂中6Li和7Li的宏观吸收截面大致相当;随着6Li摩尔含量的增大,冷却剂的温度反应性系数由负向正转变,并逐渐增大;基于四因子公式的分析表明,引起冷却剂的温度反应性系数由负变正的主要因素为热中子利用系数的变化。
Ball bed fluoride salt cooling high-temperature reactors as the fourth generation reactors, use 2LiF-BeF2 as coolant. 2LiF-BeF2 contains 6Li nuclides with large micro-absorption cross-section, and the molar content of 2LiF-BeF2 will influence the temperature reactivity coefficient of coolant. Therefore, it is necessary to study the effect of 6Li molar content on coolant temperature reactivity coefficient. In this paper, the infinitesimal ball bed is used as a model to study the coolant temperature reactivity coefficients of different 6Li molar content by using SCALE6 (Standardized Computer Analyzes for Licensing Evaluation). The results show that when the content of 6Li in the coolant accounts for 0.005% of the total amount of Li, the macroscopic absorption cross sections of 6Li and 7Li in the coolant are approximately the same. With the increase of 6Li molar content, the temperature reactivity coefficient From negative to positive transition, and gradually increased; based on four-factor analysis showed that the main cause of the coolant temperature reactivity coefficient from negative to positive for the thermal neutron utilization factor changes.