中文摘要：

针对核电站发生破口失水事故后碎片在燃料包壳外表面形成污垢沉积的现象,采用一维模型建立了燃料包壳和周围冷却剂温度场的数值计算模型,与流体动力学分析软件CFX模拟结果进行对比,分析污垢厚度、污垢导热系数以及冷却剂流速对包壳温升的影响,并分析包壳温升瞬态变化.经计算发现,此计算模型计算结果与CFX模拟结果相近,最大相对偏差为2%.经分析发现污垢的产生导致包壳外表面温度突升,且温度升高的幅度随着污垢厚度增大而增大,随着污垢导热系数的减小而增大.存在一个临界冷却剂入口流速,当入口流速低于临界值时,堆芯内将产生沸腾危机.

英文摘要：

Aiming at the fragments of deposit on the fuel cladding caused by the loss of coolant accident of nuclear power stations, a numerical calculation model of the temperature field on the fuel cladding and the coolant is con-structed by using the one-dimensional model.Then, the numerical calculation results are compared with the CFX simulation ones, so as to analyze the influences of the thickness of the dirt, the thermal conductivity of the dirt and the flow rate of the coolant on the temperature rise of the fuel cladding and discuss the transient change of the tem-perature rise.Calculation results show that the numerical results are close to the CFX simulation ones, with a maxi-mum relative deviation of 2%.Through an analysis, it is also found that the dirt deposition leads to a temperature rise on the fuel cladding, and the extent of temperature rise increases with the increase of the dirt thickness as well as with the decrease of the thermal conductivity of the dirt.In addition, it is found that there exists a critical inlet flow rate of coolant, and a boiling crisis occurs in the reactor core when the inlet flow rate of coolant is below the critical value.