中国先进研究堆启动临界外推优化研究  

Optimization of critical extrapolation for the restart of China advanced research reactor

作　　者：冉怀昌 甄建霄 李建龙[1] 葛艳艳[1] 王玉林[1] RAN Huaichang;ZHEN Jianxiao;LI Jianlong;GE Yanyan;WANG Yulin(China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院,北京102413

出　　处：《核技术》2020年第12期82-87,共6页Nuclear Techniques

基　　金：中国先进研究堆运行与改造项目资助。

摘　　要：中国先进研究堆(China Advanced Research Reactor,CARR)长时间停堆后重新启动需进行临界外推,重水光激中子既是反应堆启动中子源,也是探测器本底。外推过程中,本底使外推曲线呈“凸”状,使外推的临界棒位均大于实际临界棒位,这样的外推过程是危险的。曲线拟合的方法可以得到探测器中子本底值和反应堆临界棒位,采用拟合得到的本底值来修正外推临界棒位,使外推结果明显改善,修正的外推棒位基本上满足实验棒位和探测中子计数倒数线性关系。同时,拟合得到的临界棒位也是反应堆临界棒位的重要参考值。在外推过程中,随着数据的增多,修正的临界棒位越来越接近临界棒位,曲线拟合得到的临界棒位值偏离也越来越小,明显改善了外推过程。[Background]Critical extrapolation is necessary during the restart of China advanced research reactor(CARR)after a long shutdown period.The photoneutron in the heavy water tank is not only the neutron source during the reactor restart,but also the background of the detector.During the extrapolation process,the background neutron makes the extrapolation curve"convex",and the extrapolated critical rod position is overtakes the actual critical rod position,so the extrapolation process is dangerous.[Purpose]This study aims to optimize critical extrapolation by making use of neutron background value of detector.[Methods]Based on the control rod grid worth curve in CARR and extrapolation formula,the background value was obtained by fitting method to improve the extrapolation process.The critical extrapolation formula of control rod was derived,and the background value was obtained by fitting with the measured neutron numbers corresponding to different rod positions in the experiment.Then,the background value was applied to the correction of extrapolated critical rod position value.[Results]The extrapolation results show obvious improvement,and the modified extrapolated rod position basically satisfies the linear relationship between the experimental rod position and the reciprocal of detection neutron count.[Conclusions]The data fitting method can get the background value of the detector,which can significantly improve the extrapolation process.

关 键 词：中国先进研究堆 临界外推 曲线拟合 本底值 

分 类 号：TL375.5[核科学技术—核技术及应用]