基于蒙特卡洛方法的燃料组件压紧力研究

An Investigation on the Hold-down Force of Fuel Assembly Based on Monte Carlo Algorithm

燃料组件压紧力受多个因素的影响,当前的确定论方法中,采用保守的假设,这些参数均取对燃料组件压紧最不利影响的值。随着目前工程上燃料组件燃耗的不断提高,采用这种方法已不能满足各工程项目的要求。文章研究了蒙特卡洛方法在压紧力计算中的运用,通过与目前在工程上采用的确定论分析方法的计算结果进行对比。采用蒙特卡洛方法能够获得更大的压紧力裕量,减小了分析方法及保守的假设带来的过度保守性,更能满足工程上对压紧的要求。文章还对比了最大压紧力和最小压紧力之间的极差的变化,分析了两种压紧力计算方法结果的离散度。采用蒙特卡洛方法计算的燃料组件压紧力极差更小,离散度低,数据更精确,为设计压紧系统时避免过大的压紧力提供指导。

The hold-down force of the fuel assembly is affected by many factors.In the current deterministic methodology,conservative assumptions are used.These parameters take the value that has the most adverse effect on the hold-down of the fuel assembly.With the continuous increase of burn-up,this method cannot meet the requirements of nuclear power projects.An investigation was carried out using Monte-carlo algorithm.By comparing with the calculation results of the deterministic methodology currently used in projects,more margins were gained,and reduced over-conservativeness due to analytical methods and conservative assumptions,which can meet the need in nuclear power projects.This paper also compares the range between the maximum and the minimum hold-down forces,and analyzes the dispersion of the two hold-down force calculation methods.The little dispersion is got with Monte Carlo algorithm,which means the result is more accurate.This provides guidance for avoiding excessive hold-down force when designing the hold-down system.