Analysis of Doppler coefficients for typical PWR UO2 and MTR U3Si2-Al fuels using ENDF/B-VI and VII

作者：Kim Kyung O; Jo Daeseong^*

来源：Annals of Nuclear Energy, 2015, 85: 1024-1028.

DOI：10.1016/j.anucene.2015.07.021

• Doppler coefficient
• PWR UO2
• MTR U3Si2-Al
• ENDF/B-VI
• ENDF/B-VII

This study was performed to evaluate the Doppler coefficients for two types of uranium fuels and to investigate the effect of the neutron cross-section on these evaluations. A series of calculations was performed using MCNP6.1 and KENO6 codes which are three-dimensional neutron transport codes based on Monte Carlo method. The typical PWR UO2 lattice and the Material Testing Reactor (MTR) U3Si2-Al lattice were considered as fuel models of this study. The latest cross-sections (ENDF/B-VI and VII) at the desired temperatures were also generated from the makxsf code, and applied to the MCNP calculations. As a result, there were some differences (about 300-400 pcm) among the neutron multiplication factors (k(eff)) at each enrichment because of the codes and nuclear data used in these evaluations. Although the Doppler coefficient was changed to be less negative with increasing uranium enrichment regardless of types of nuclear fuel, their behaviors were significantly different between those. The Doppler coefficient for UO2 fuel followed an asymptotic curve, while the coefficient for the other followed an exponential curve which more significantly became less negative with increasing uranium enrichment. Also, the Doppler coefficient for UO2 fuel was about 2 times more negative than those for U3Si2-Al fuel. It was estimated that additional study was required for investigating the cause of occurrence because there was a difference more than two standard deviation (2 sigma) between the Doppler coefficients derived from different cross-sections at some enrichments.

• 出版日期2015-11