随机中子动力学及其数值模拟研究进展

Progress in Research on Stochastic Neutron Dynamics and Its Numerical Simulation

随机中子动力学是核动力设计和核反应堆安全中的重要课题,本文从随机中子动力学的基础概念和研究方法出发,介绍随机中子动力学研究的历史发展和研究现状.裂变中子与光子的多重性是反应堆零功率中子噪声主要来源,对中子涨落的方程描述及其求解,演化出零功率中子噪声与功率反应堆噪声的随机理论.随机中子动力学的重要应用包括反应性微观测量、功率反应堆噪声测量和分析、核临界漂移分析和核材料识别与检测等.在半个多世纪的研究中,以脉冲堆点火过程的脉冲爆发等待时间分布为代表的随机性,一直缺乏定量分析方法和工具.直到近几年,模拟随机中子动力学过程的广义半马尔科夫过程模拟方法取得了重要进展,很好地揭示了脉冲堆实验中子点火规律.最后讨论随机中子动力学研究中有待解决的研究课题.

Stochastic neutron dynamics is important task in nuclear power plant design and nuclear reactor safety.In this paper,basic concepts and research methods for stochastic neutron kinetics are introduced and historical development and research status in the field are sketched out.Multiplicities of fission neutrons and photons are main sources of zero power reactor noise.Based on description equation of neutron fluctuation and its solution,stochastic theory of zero power and power reactor noise is evolved.Stochastic neutron dynamics are applied in important areas such as reactivity microscopic measurement,power reactor noise measurement and analysis,nuclear criticality excursion analysis,nuclear material detection and identification and so on.In the past half century,however,it lacks available method and tool to implement quantitative analysis of problems such as probability distribution of burst waiting time of neutron initiation in pulse reactor.In recent years,important progress is made in generalized semi-Markov process simulation method,which is applied to stochastic neutron kinetic process simulation.It reveals inherent law of neutron initiation experiments conducted in pulse reactor.At last,research topics to be solved in stochastic neutron dynamics are discussed.