基于RELAP5和子通道程序的熔盐冷却快堆多尺度热工流体耦合程序开发及应用

Development and application of multi-scale thermal fluid coupling program for molten salt cooled fast reactor based on RELAP5 and sub-channel program

自然循环氯盐冷却快堆具有结构简单、固有安全性高和经济性好等特点,是一种非常具有发展潜力的第四代先进核能系统。采用全自然循环驱动的45 MWth小型自然循环氯盐冷却快堆(Small Natural Circulation Chloride Cooled Fast Reactor,SN3CFR)一回路设计,由于系统分析程序堆芯热工模型较为简化,无法模拟堆芯内部详细的紊流交混和横流混合等三维热工流体现象。为了更加精确和高效地开展一回路自然循环热工安全特性研究,基于熔盐冷却快堆子通道分析程序ThorSUBTH和系统分析程序RELAP5-TMSR,开发了适用于熔盐冷却快堆多尺度热工流体耦合程序。通过水平圆管算例和简单闭合循环回路算例开展了耦合程序验证;为进一步评估其适用性,针对SN3CFR自然循环一回路主冷却系统,建立了多尺度模型,计算了反应堆稳态运行参数,分析了反应性引入事故瞬态。结果表明:多尺度热工耦合程序算例计算值与参考结果吻合良好,验证了程序正确性;SN3CFR在额定功率工况下计算值与设计值符合良好,在反应性引入事故工况下各关键热工参数均满足设计限值,验证了耦合程序的适应性。多尺度热工流体耦合程序能够为自然循环熔盐冷却堆的系统设计、优化和安全分析提供有效的计算和分析工具,具有重要的工程意义。

[Background]The natural circulation chloride cooled fast reactor(N3CFR)has the characteristics of simple structure,high inherent safety and good economy.It is an advanced fourth-generation nuclear energy system with development potential.However,we are not able to calculate 3D thermal fluids in core when modeled using RELAP5-TMSR.[Purpose]This study aims to improve the applicability and accuracy of the RELAP5-TMSR program in transient analysis and safety assessment of small natural circulation chloride cooled fast reactor(SN3CFR).[Methods]Firstly,the coupling code was developed with an external explicit method,and verified by the horizontal tube model based on the system analysis code RELAP5-TMSR and the sub-channel code ThorSUBTH.Then,according to the natural circulation primary circuit main cooling system,a multiscale model of the SN3CFR was established to evaluate the applicability of the coupled code.Finally,the reactor steady-state operating parameters and the reactivity insertion incident conditions were calculated and analyzed.[Results]The results show that the coupling code is in good agreement with the verification examples,and all key thermal parameters of SN3CFR meet design limits under reactive introduction accident conditions.[Conclusions]The development of a multiscale thermal hydraulics coupling code can perform system analysis fast and calculate the thermal fluid of the core more accurately,which is of great significance for the system design,safety analysis and optimization of molten salt cooled reactors.