压水堆核电站燃料组件弯曲对堆芯中子学的影响分析计算

在压水堆核电站中,由于燃料组件装配的压紧力、冷却剂流动、辐射蠕变、燃耗等因素会导致燃料组件的弯曲,燃料组件的弯曲对组件间的水隙分布产生影响,从而影响中子的慢化行为及堆芯的传热性能,进而对反应堆堆芯的运行参数造成影响。本文分析了组件弯曲的成因及机理、影响及后果（包括对堆芯功率分布、径向功率倾斜、焓升因子、热点因子等参数的影响）,并使用蒙特卡罗软件JMCT,对组件弯曲的确定论计算程序的正确性进行了验证。最后通过确定论的计算程序模块,对CPR1000核电站的组件弯曲情况进行了模拟分析,计算结果表明:在某一燃耗下,随着水隙增加或减小,燃料组件功率会随之增加或减小,使堆芯的功率分布发生倾斜,影响核电站的安全运行。

Analysis and calculation on core neutronics affected by the assembly bowing in pressurized water reactor nuclear power plant

In a pressurized water reactor nuclear power plant, the compression force of the fuel assembly, coolant flow, radiation creep, burnup and other factors will cause the bowing of the fuel assembly. The bowing of the fuel assembly affects the distribution of the water gap between the assemblies. It affects the slowing behavior of neutrons and the heat transfer performance of the core, which in turn affects the operating parameters of the reactor core. This paper discusses the cause and mechanism, influence and consequences of assembly bowing (including the influence on core power distribution, core radial power tilt, nuclear enthalpy rise hot channel factor, heat flux hot channel factor and other parameters), and uses Monte Carlo software JMCT to verify the correctness of the calculation program of component bowing PCM. Finally, through the deterministic calculation program, a simulation analysis of the assemblies bowing of the CPR1000 nuclear power plant is carried out. The calculation results show that: at certain fuel consumption, as the water gap increases or decreases, the fuel assembly power will increase or decrease, the power distribution of the core will tilt, affecting the safe operation of nuclear power plants.