随机中子动力学应用

发布时间：2018-04-28 13:45

本文选题：随机中子场 + 核临界安全　；参考：《中国工程物理研究院》2016年博士论文

【摘要】：随机中子动力学研究中子在裂变材料中输运的随机过程。中子与介质相互作用以及源中子出射等都是随机过程,导致中子输运存在随机性,这种随机效应一般是可以忽略的,但在弱中子源(简称弱源)条件下是很重要的。在次临界裂变系统中,可通过弱中子场的涨落信息获取增殖系统的中子学参数,相关研究在裂变装置反应性测量和核材料检测等领域得到广泛应用。在超临界裂变系统中,弱中子场随机过程导致中子脉冲爆发时间的随机性,该过程在临界反应堆启动、核武器点火和超临界事故评价与分析中十分要紧,它决定了裂变系统在脉冲爆发时所处的状态。随机中子动力学研究始于20世纪50年代,主要的研究手段是脉冲堆弱源点火实验和次临界中子噪声测量。半个多世纪以来,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2011年,模拟随机中子动力学过程的广义半马尔科夫过程(GSMP)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。本文对GSMP模拟方法的理论和数学基础进行完善,给出了详细的算法设计原理和实施策略。运用该方法解释了Godiva和Caliban上的脉冲实验结果,进一步验证了GSMP模拟方法的正确性和可行性。把GSMP模拟方法引入到点堆中子动力学方程(PKEs)的求解中,对数值方法的实现策略做了详细的研究,并对反应性变化对中子代时间的影响给予关注。在核工业领域,核临界安全至关重要,核燃料加工与乏燃料处理是核临界事故的易发环节。这类事故多发生在弱源条件下,中子场的早期随机过程的影响不可忽略,尽管核临界事故的评价与分析方法得到深入研究,但对这一因素缺乏定量分析方法。本文结合GSMP方法对随机中子场瞬态的模拟和对PKEs的求解,发展了弱源启动的核临界安全评价与分析的方法和程序。为了摆脱对裂变系统动力学参数的依赖,有必要基于GSMP模拟方法研制一个三维连续能量粒子输运的瞬态MC程序。为此,本文开展了相关的理论研究、算法构造和优化、数据结构和程序框架的设计工作,并完成了TiBES程序的研制和考核。该程序除了在弱中子场瞬态模拟中的应用外,本文还试图研究该方法应用到时空中子动力学方程求解中的可行性。
[Abstract]:Random neutrons dynamics study the random process of neutron transport in fission materials. The interaction of neutrons with the medium and the source neutron emission are random processes, which lead to the randomness of the neutron transport. This random effect is generally negligible, but it is very important in the weak source (short source) condition. In the system, the neutron parameters of the proliferation system can be obtained by the fluctuation information of the weak neutron field. The related research is widely used in the field of reactivity measurement and nuclear material detection in the fission device. In the supercritical fission system, the random process of the weak neutron field causes the randomness between the time of the burst of the neutron pulse, and the process is started at the critical reactor. Nuclear weapon ignition and critical accident evaluation and analysis are very important. It determines the state of the fission system in the pulse burst. The random neutron dynamics study began in 1950s. The main research means are the pulse reactor ignition experiment and the subcritical neutron noise measurement. The pulse reactor has been ignited for more than half a century. There is a lack of quantitative analysis methods and tools. Until 2011, important progress has been made in the generalized semi Markov process (GSMP) simulation method to simulate the stochastic neutron dynamics process. The law of ignition of the pulsed reactor is well revealed. The principle of the GSMP simulation method is discussed in this paper. The theory and the mathematical basis are perfected, and the detailed algorithm design principle and implementation strategy are given. Using this method, the results of the pulse experiment on Godiva and Caliban are explained, and the correctness and feasibility of the GSMP simulation method are further verified. The GSMP simulation method is introduced to the solution of the neutron dynamic equation (PKEs) of the point heap, and the numerical method is applied to the numerical method In the nuclear industry, nuclear fuel processing and spent fuel treatment are the easy links of Nuclear Critical accidents. This kind of accident occurs mostly in the weak source conditions, and the effect of the early random process of the neutron field cannot be ignored. Although the evaluation and analysis methods of Nuclear Critical accidents are studied in depth, the quantitative analysis method is lacking for this factor. In this paper, the methods and procedures for the critical safety evaluation and analysis of the weak source start are developed by combining the simulation of the random neutron field transient and the solution of the PKEs by the GSMP method. Depending on the number of dependencies, it is necessary to develop a transient MC program for a three-dimensional continuous energy particle transport based on the GSMP simulation method. To this end, the relevant theoretical research, algorithm construction and optimization, the design of the data structure and program framework are carried out, and the development and assessment of the TiBES program are completed. This program is not only in the weak neutron field transient simulation. In addition, we also try to study the feasibility of this method in solving the equations of spacetime neutron dynamics.

【学位授予单位】：中国工程物理研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O571.5

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