反应堆内几种常用核素的多普勒效应研究

反应堆从零功率到满功率运行中,其中燃料和结构材料的温度范围都跨度很大.由于多普勒效应的存在,仅仅使用MCNP自带的常温下的点截面数据库不能够计算如反应性温度系数这样与温度相关的物理参数的量.为了定量地了解反应堆中几种常用核素的多普勒效应,使用NJOY加工这些核素,得到较高温度下的ACE格式点截面数据,并对比它们的多普勒展宽情况,发现238 U和240Pu等重核的多普勒效应最为明显.最后通过对238 U、240 Pu重核随着温度升高的多普勒展宽程度,预测到以铀、钚等为燃料的反应堆中,多普勒效应所引起温度系数的绝对值趋于减小.

Study on Doppler Effects of Some Frequently Used Radionuclide in Reactors

From zero to full power operation,the temperature range of reactor power fuels and structural materials are of a great span.Thus,by using the point cross section database under room temperature in MCNP alone,the physical parameters,such as the reactive temperature coefficient related to the reaction temperature can not be obtained due to the existence of the Doppler effects.In this paper,the Doppler effects of the several radio-nuclides frequently using in reactors are studied quantitatively by suing NJOY software.By analyzing the temperature ACE format point-sectional data under higher temperatures,and comparing the Doppler broadening of the radio-nuclides,one can come to the conclusion that Doppler effects of 238U and 240Pu are the strongest.The last but not the least,we can predict that the absolute value of the temperature coefficient calculate caused by the Doppler effects tend to dearease.