RELAP5-3D在固态燃料TMSR热工水力计算中的初步适用性分析

Preliminary Analysis on Capability of RELAP5-3D in Solid Fuel TMSR Thermal-hydraulic Simulation

钍基熔盐堆(TMSR)是第4代裂变反应堆,由FLIBE熔盐作冷却剂,能在高温下工作,并具有较高的热效率。TMSR堆芯由球形燃料组成,几何结构复杂,需采用三维模型,因此应用RELAP5-3D建立三维模型方法来代替传统的一维建模系统分析方法是很有必要的。文章研究了RELAP5-3D在TMSR热工水力计算中的适用性分析,通过比较RELAP5-3D与适用于TMSR的传热模型和压降模型,得到层流、湍流、过渡流传热经验关系式和压降关系式的差别,从而分析了RELAP5-3D的适用性。结合RELAP5-3D三维建模的特点,对TMSR堆芯进行三维建模,并进行稳态调试计算。在相同条件下,通过与CFX进行堆芯轴向温度结果对比,进一步验证了RELAP5-3D在TMSR三维堆芯建模中的可行性。在原有TMSR堆芯模型基础上,加入泵和换热器,形成完整的一回路模型,并进行稳态计算和LOFC事故分析。通过初步的理论分析与建模计算,证明RELAP5-3D在固态燃料TMSR热工水力计算中具备一定的适用性,可用于初步热工水力系统分析。

Thorium-based molten salt reactor （TMSR） is one of the fourth generation nuclear fission reactors. It uses FLIBE as the coolant, is capable of operating at high temperatures and has a high thermal efficiency. As the core of TMSR is composed of fuel pebbles and has a complex structure, three-dimensional model should be used. The research of using a three-dimensional model of RELAPS-3D method to replace the traditional one-dimensional system analysis is necessary. The applicability of RELAPS-3D in TMSR thermal-hydraulic simulation was analyzed by comparing the heat transfer model and pressure drop model of RELAPS-3D with the ones compatible for TMSR. The differences of the laminar flow, turbulence, convection transition empirical correlations and pressure drop empirical correlations were analyzed in order to verify the applicability of RELAP5-3D. According to RELAP5-gD three-dimensional modeling features, the three-dimensional core model of TMSR was set up and steady-state calculation was executed and achieved. Under the same conditions, the results of core axial temperature were compared between RELAP5-3D and CFX, which further verify that the three- dimensional modeling capability of RELAP5-3D is feasibility for TMSR. The TMSR core model was modified as a full loop model with pipes, pump and heat exchanger added. The steady-state calculation and LOFC accident simulation were executed and achieved. In general, according to the preliminary analysis and calculation, RELAP5-3D is basically feasible for TMSR thermal-hydraulic simulation and capable of preliminary thermal-hydraulic system analysis.