【摘要】：釷基熔鹽堆-固態(tài)燃料2號堆(TMSR-SF2)是基于球床熔鹽堆固態(tài)燃料1號堆(SF1)的小型模塊化堆型,這種新型概念堆吸收了SF1的氟鹽冷卻劑、包覆材料顆粒、高溫低壓運(yùn)行、高熱惰性、高安全裕度、高燃耗球床、在線換料、非能動余熱排出系統(tǒng)等諸多優(yōu)點(diǎn),并通過小型模塊化思維引入了包括簡約系統(tǒng),小體積優(yōu)勢、一體化設(shè)計、建造運(yùn)輸組裝流程模塊化、低啟動資金、多模塊功率調(diào)節(jié)、核熱應(yīng)用在內(nèi)的新特點(diǎn),相較SF1擁有顯著的經(jīng)濟(jì)性與安全性優(yōu)勢。小型模塊化反應(yīng)堆目前已成為國內(nèi)外研究的前沿領(lǐng)域,SF2作為TMSR-SF系列的下一代堆型,其熱工水力設(shè)計與安全事故分析具有重要的研究意義與戰(zhàn)略價值。本文第一部分基于熔鹽堆與小型模塊化反應(yīng)堆調(diào)研結(jié)果,提出了SF2的初步設(shè)計方案。然后使用Fluent軟件完成了堆芯各部件與整體的熱工水力設(shè)計,主要包括以下幾方面關(guān)鍵問題:(1)下降環(huán)腔與下腔室設(shè)計,緩解了局部湍流對結(jié)構(gòu)的沖擊效應(yīng);(2)反射層熔鹽孔道與活性區(qū)進(jìn)出口擋板設(shè)計,顯著降低了壓降并展平了溫度分布;(3)上腔室設(shè)計,強(qiáng)化了冷卻劑攪渾程度;(4)球床穩(wěn)態(tài)與瞬態(tài)模擬,求解了溫度分布與響應(yīng)時間。除此之外,還使用經(jīng)驗(yàn)與理論關(guān)系式完成了熔鹽換熱器與RVACS的初步計算。最終基于模擬結(jié)果完成了SF2的初步方案的優(yōu)化設(shè)計,為安全事故分析提供了基本輸入?yún)?shù)。本文第二部分使用RELAP軟件開展了安全事故分析,研究工作包括以下內(nèi)容:(1)對SF2進(jìn)行全堆節(jié)點(diǎn)化建模并對比驗(yàn)證了模型的等效性;(2)完成了一系列典型事故的模擬與分析,證明了SF2的高安全性,且安全系統(tǒng)與固有安全性具有的良好的互補(bǔ)性;(3)證明了小型模塊化設(shè)計對事故種類、進(jìn)程與物理現(xiàn)象的顯著簡化與整合作用;(4)通過一系列瞬態(tài)擾動事件的模擬與分析證明了固有安全性的高穩(wěn)定作用;(5)綜合考慮各類繼發(fā)事件與安全策略,提出了依靠主循環(huán)泵冷卻堆芯的事故緩解措施,驗(yàn)證了熱惰性在固有安全性中的重要地位和強(qiáng)化手段;(5)對主要安全系統(tǒng)進(jìn)行了不確定性研究,對其系統(tǒng)設(shè)計裕度提出了具體要求,證明了RVACS在事故前期與后期的局限性,給出了相應(yīng)改進(jìn)方法;(6)開展了關(guān)鍵反應(yīng)性參數(shù)的敏感性分析,證明了冷卻劑反應(yīng)性反饋在瞬態(tài)擾動中的穩(wěn)定作用;(7)發(fā)現(xiàn)了事故后期回路因自然循環(huán)產(chǎn)生的振蕩與逆流現(xiàn)象,揭示了其生成機(jī)制。最后通過比較分析事故模擬結(jié)果,總結(jié)了安全特性,提出了事故策略選擇,證明了SF2當(dāng)前設(shè)計可以滿足主要安全設(shè)計準(zhǔn)則。
[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.
【學(xué)位授予單位】：中國科學(xué)院研究生院(上海應(yīng)用物理研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TL33;TL426
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本文編號：2425579