铅冷快堆燃料棒芯块热裂纹机理与数值模拟

Mechanism and Numerical Simulation of Heat-induced Crack in Fuel Pellet of Lead Cooled Fast Reactor

核反应堆工作时,燃料棒内的温度最高,导致燃料棒芯块产生很大的热应力与应变,因而燃料棒芯块经常发生径向开裂破坏(龟裂)。采用数值模拟方法分析了燃料棒芯块开裂的力学机理,在ABAQUS软件中用Python语言进行了二次开发,估算了燃料棒芯块的径向开裂情况。发现燃料棒产热功率越大、芯块直径越大,芯块越容易发生径向开裂,开裂块数随着产热功率增加而增加。当芯块直径为7.8 mm时,芯块产热功率为100 MW/m^3不会发生开裂。当产热功率为200、300、400 MW/m^3时,最小开裂块数为3、4、6块,与工程实际中观察到的燃料芯块裂纹形状与开裂块数基本一致。

When the nuclear reactor is working,the temperature in the fuel rod is very high,which results in large thermal stress and strain in the fuel rod core block.Thus,the fuel rod core block is often suffered from radial cracking.Therefore,the numerical simulation method was used to analyze the mechanical mechanism of fuel rod core block cracking.The secondary development was carried out by Python language in ABAQUS software,and the radial cracking of fuel rod core block was estimated.It is found that the larger the heat production power and the diameter of the core block,the more likely the core block is to crack radially.And the number of cracked blocks increases with the increase of heat production power.When the diameter of the core block is 7.8 mm and the heat production power 100 MW/m^3,the core block will not crack.When the heat production rate is 200,300 and 400 MW/m^3,respectively,the minimum number of cracked blocks is 3,4 and 6 respectively.It is basically consistent with the crack shape and number of cracked blocks observed in the engineering practice.