本文選題：隨機中子場 + 核臨界安全�。� 參考：《中國工程物理研究院》2016年博士論文

【摘要】：隨機中子動力學研究中子在裂變材料中輸運的隨機過程。中子與介質(zhì)相互作用以及源中子出射等都是隨機過程,導致中子輸運存在隨機性,這種隨機效應一般是可以忽略的,但在弱中子源(簡稱弱源)條件下是很重要的。在次臨界裂變系統(tǒng)中,可通過弱中子場的漲落信息獲取增殖系統(tǒng)的中子學參數(shù),相關(guān)研究在裂變裝置反應性測量和核材料檢測等領(lǐng)域得到廣泛應用。在超臨界裂變系統(tǒng)中,弱中子場隨機過程導致中子脈沖爆發(fā)時間的隨機性,該過程在臨界反應堆啟動、核武器點火和超臨界事故評價與分析中十分要緊,它決定了裂變系統(tǒng)在脈沖爆發(fā)時所處的狀態(tài)。隨機中子動力學研究始于20世紀50年代,主要的研究手段是脈沖堆弱源點火實驗和次臨界中子噪聲測量。半個多世紀以來,以脈沖堆點火過程的脈沖爆發(fā)等待時間分布為代表的隨機性,一直缺乏定量分析方法和工具。直到2011年,模擬隨機中子動力學過程的廣義半馬爾科夫過程(GSMP)模擬方法取得了重要進展,很好地揭示了脈沖堆實驗中子點火規(guī)律。本文對GSMP模擬方法的理論和數(shù)學基礎(chǔ)進行完善,給出了詳細的算法設(shè)計原理和實施策略。運用該方法解釋了Godiva和Caliban上的脈沖實驗結(jié)果,進一步驗證了GSMP模擬方法的正確性和可行性。把GSMP模擬方法引入到點堆中子動力學方程(PKEs)的求解中,對數(shù)值方法的實現(xiàn)策略做了詳細的研究,并對反應性變化對中子代時間的影響給予關(guān)注。在核工業(yè)領(lǐng)域,核臨界安全至關(guān)重要,核燃料加工與乏燃料處理是核臨界事故的易發(fā)環(huán)節(jié)。這類事故多發(fā)生在弱源條件下,中子場的早期隨機過程的影響不可忽略,盡管核臨界事故的評價與分析方法得到深入研究,但對這一因素缺乏定量分析方法。本文結(jié)合GSMP方法對隨機中子場瞬態(tài)的模擬和對PKEs的求解,發(fā)展了弱源啟動的核臨界安全評價與分析的方法和程序。為了擺脫對裂變系統(tǒng)動力學參數(shù)的依賴,有必要基于GSMP模擬方法研制一個三維連續(xù)能量粒子輸運的瞬態(tài)MC程序。為此,本文開展了相關(guān)的理論研究、算法構(gòu)造和優(yōu)化、數(shù)據(jù)結(jié)構(gòu)和程序框架的設(shè)計工作,并完成了TiBES程序的研制和考核。該程序除了在弱中子場瞬態(tài)模擬中的應用外,本文還試圖研究該方法應用到時空中子動力學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.

【學位授予單位】：中國工程物理研究院
【學位級別】：博士
【學位授予年份】：2016
【分類號】：O571.5

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