小型模块化固态燃料熔盐堆TMSR-SF2的热工水力设计与安全事故分析
发布时间：2019-02-17 20:56
【摘要】：钍基熔盐堆-固态燃料2号堆(TMSR-SF2)是基于球床熔盐堆固态燃料1号堆(SF1)的小型模块化堆型,这种新型概念堆吸收了SF1的氟盐冷却剂、包覆材料颗粒、高温低压运行、高热惰性、高安全裕度、高燃耗球床、在线换料、非能动余热排出系统等诸多优点,并通过小型模块化思维引入了包括简约系统,小体积优势、一体化设计、建造运输组装流程模块化、低启动资金、多模块功率调节、核热应用在内的新特点,相较SF1拥有显著的经济性与安全性优势。小型模块化反应堆目前已成为国内外研究的前沿领域,SF2作为TMSR-SF系列的下一代堆型,其热工水力设计与安全事故分析具有重要的研究意义与战略价值。本文第一部分基于熔盐堆与小型模块化反应堆调研结果,提出了SF2的初步设计方案。然后使用Fluent软件完成了堆芯各部件与整体的热工水力设计,主要包括以下几方面关键问题:(1)下降环腔与下腔室设计,缓解了局部湍流对结构的冲击效应;(2)反射层熔盐孔道与活性区进出口挡板设计,显著降低了压降并展平了温度分布;(3)上腔室设计,强化了冷却剂搅浑程度;(4)球床稳态与瞬态模拟,求解了温度分布与响应时间。除此之外,还使用经验与理论关系式完成了熔盐换热器与RVACS的初步计算。最终基于模拟结果完成了SF2的初步方案的优化设计,为安全事故分析提供了基本输入参数。本文第二部分使用RELAP软件开展了安全事故分析,研究工作包括以下内容:(1)对SF2进行全堆节点化建模并对比验证了模型的等效性;(2)完成了一系列典型事故的模拟与分析,证明了SF2的高安全性,且安全系统与固有安全性具有的良好的互补性;(3)证明了小型模块化设计对事故种类、进程与物理现象的显著简化与整合作用;(4)通过一系列瞬态扰动事件的模拟与分析证明了固有安全性的高稳定作用;(5)综合考虑各类继发事件与安全策略,提出了依靠主循环泵冷却堆芯的事故缓解措施,验证了热惰性在固有安全性中的重要地位和强化手段;(5)对主要安全系统进行了不确定性研究,对其系统设计裕度提出了具体要求,证明了RVACS在事故前期与后期的局限性,给出了相应改进方法;(6)开展了关键反应性参数的敏感性分析,证明了冷却剂反应性反馈在瞬态扰动中的稳定作用;(7)发现了事故后期回路因自然循环产生的振荡与逆流现象,揭示了其生成机制。最后通过比较分析事故模拟结果,总结了安全特性,提出了事故策略选择,证明了SF2当前设计可以满足主要安全设计准则。
[Abstract]:Thorium base molten salt reactor-solid fuel reactor 2 (TMSR-SF2) is a small modular reactor based on ball bed molten salt solid fuel reactor 1 (SF1). This new concept reactor absorbs the fluorine coolant of SF1, coated material particles, and operates at high temperature and low pressure. Many advantages such as high thermal inertia, high safety margin, high burn-up ball bed, on-line reloading, inactive residual heat removal system and so on, are introduced through small modular thinking, including simple system, small volume advantage, integrated design, etc. The new features such as modularization of construction transportation assembly process, low start-up fund, multi-module power regulation and nuclear heat application have significant advantages over SF1 in economy and safety. As the next generation reactor of TMSR-SF series, SF2 has great significance and strategic value in thermal hydraulic design and safety accident analysis. In the first part of this paper, based on the investigation results of molten salt reactor and small modular reactor, a preliminary design scheme of SF2 is proposed. Then the thermohydraulic design of the core components and the whole system is completed by using Fluent software, which mainly includes the following key problems: (1) the design of the descending ring cavity and the lower chamber, which alleviates the impact effect of local turbulence on the structure; (2) the design of inlet and outlet baffle of molten salt channel and active zone in reflective layer can significantly reduce the pressure drop and flatten the temperature distribution, (3) the design of the upper chamber strengthens the muddy degree of the coolant; (4) the steady state and transient simulation of the ball bed, the temperature distribution and the response time are solved. In addition, the preliminary calculation of molten salt heat exchanger and RVACS has been done by using empirical and theoretical relations. Finally, based on the simulation results, the optimization design of the initial scheme of SF2 is completed, which provides the basic input parameters for the safety accident analysis. In the second part of this paper, the safety accident analysis is carried out by using RELAP software. The research work includes the following contents: (1) the full-heap nodal modeling of SF2 is carried out and the equivalence of the model is compared and verified; (2) A series of typical accidents are simulated and analyzed, which proves the high security of SF2 and the good complementarity between the safety system and the inherent safety. (3) it is proved that the miniature modular design can simplify and integrate the accident types, processes and physical phenomena, (4) the high stability of inherent security is proved by the simulation and analysis of a series of transient disturbance events. (5) considering all kinds of secondary incidents and safety strategies, the accident mitigation measures which rely on the core cooling of the main circulating pump are put forward, and the importance of thermal inertia in the inherent safety is verified and the strengthening means are proved. (5) the uncertainty of the main safety system is studied, the design margin of the system is put forward, the limitation of RVACS in the early and late period of the accident is proved, and the corresponding improvement method is given. (6) sensitivity analysis of key reactivity parameters is carried out, which proves the stabilizing effect of reactivity feedback of coolant in transient disturbance. (7) Oscillation and countercurrent phenomena caused by natural circulation in the later stage of the accident are found, and the formation mechanism is revealed. Finally, by comparing and analyzing the results of accident simulation, the safety characteristics are summarized, and the choice of accident strategy is put forward. It is proved that the current design of SF2 can meet the main safety design criteria.
【学位授予单位】：中国科学院研究生院(上海应用物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TL33;TL426
，
本文编号：2425579
[Abstract]:Thorium base molten salt reactor-solid fuel reactor 2 (TMSR-SF2) is a small modular reactor based on ball bed molten salt solid fuel reactor 1 (SF1). This new concept reactor absorbs the fluorine coolant of SF1, coated material particles, and operates at high temperature and low pressure. Many advantages such as high thermal inertia, high safety margin, high burn-up ball bed, on-line reloading, inactive residual heat removal system and so on, are introduced through small modular thinking, including simple system, small volume advantage, integrated design, etc. The new features such as modularization of construction transportation assembly process, low start-up fund, multi-module power regulation and nuclear heat application have significant advantages over SF1 in economy and safety. As the next generation reactor of TMSR-SF series, SF2 has great significance and strategic value in thermal hydraulic design and safety accident analysis. In the first part of this paper, based on the investigation results of molten salt reactor and small modular reactor, a preliminary design scheme of SF2 is proposed. Then the thermohydraulic design of the core components and the whole system is completed by using Fluent software, which mainly includes the following key problems: (1) the design of the descending ring cavity and the lower chamber, which alleviates the impact effect of local turbulence on the structure; (2) the design of inlet and outlet baffle of molten salt channel and active zone in reflective layer can significantly reduce the pressure drop and flatten the temperature distribution, (3) the design of the upper chamber strengthens the muddy degree of the coolant; (4) the steady state and transient simulation of the ball bed, the temperature distribution and the response time are solved. In addition, the preliminary calculation of molten salt heat exchanger and RVACS has been done by using empirical and theoretical relations. Finally, based on the simulation results, the optimization design of the initial scheme of SF2 is completed, which provides the basic input parameters for the safety accident analysis. In the second part of this paper, the safety accident analysis is carried out by using RELAP software. The research work includes the following contents: (1) the full-heap nodal modeling of SF2 is carried out and the equivalence of the model is compared and verified; (2) A series of typical accidents are simulated and analyzed, which proves the high security of SF2 and the good complementarity between the safety system and the inherent safety. (3) it is proved that the miniature modular design can simplify and integrate the accident types, processes and physical phenomena, (4) the high stability of inherent security is proved by the simulation and analysis of a series of transient disturbance events. (5) considering all kinds of secondary incidents and safety strategies, the accident mitigation measures which rely on the core cooling of the main circulating pump are put forward, and the importance of thermal inertia in the inherent safety is verified and the strengthening means are proved. (5) the uncertainty of the main safety system is studied, the design margin of the system is put forward, the limitation of RVACS in the early and late period of the accident is proved, and the corresponding improvement method is given. (6) sensitivity analysis of key reactivity parameters is carried out, which proves the stabilizing effect of reactivity feedback of coolant in transient disturbance. (7) Oscillation and countercurrent phenomena caused by natural circulation in the later stage of the accident are found, and the formation mechanism is revealed. Finally, by comparing and analyzing the results of accident simulation, the safety characteristics are summarized, and the choice of accident strategy is put forward. It is proved that the current design of SF2 can meet the main safety design criteria.
【学位授予单位】：中国科学院研究生院(上海应用物理研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TL33;TL426
，
本文编号：2425579
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