keff uncertainty quantification and analysis due to nuclear data during the full lifetime burnup calculation for a small-sized prismatic high temperature gas-cooled reactor

Abstract

To benefit from recent advances in modeling and computational algorithms, as well as the availability of new covariance data, sensitivity and uncertainty analyses are needed to quantify the impact of uncertain sources on the design parameters of small prismatic high-temperature gascooled reactors (HTGRs). In particular, the contribution of nuclear data to the k eff uncertainty is an important part of the uncertainty analysis of small-sized HTGR physical calculations. In this study, a small-sized HTGR designed by China Nuclear Power Engineering Co., Ltd. was selected for k eff uncertainty analysis during full lifetime burnup calculations. Models of the cold zero power (CZP) condition and full lifetime burnup process were constructed using the Reactor Monte Carlo Code RMC for neutron transport calculation, depletion calculation, and sensitivity and uncertainty analysis. For the sensitivity analysis, the Contribution-Linked eigenvalue sensitivity/Uncertainty estimation via Track length importance Characterization (CLUTCH) method was applied to obtain sensitive information, and the ''sandwich'' method was used to quantify the k eff uncertainty. We also compared the k eff uncertainties to other typical reactors. Our results show that 235 U is the largest contributor to k eff uncertainty for both the CZP and depletion conditions, while the contribution of 239 Pu is not very significant because of the design of low discharge burnup. It is worth noting that the radioactive capture reaction of 28 Si significantly contributes to the k eff uncertainty owing to its specific fuel design. However, the k eff uncertainty during the full lifetime depletion process was relatively stable, only increasing by 1.12% owing to the low discharge burnup design of small-sized HTGRs. These numerical results are beneficial for neutronics design and core parameters optimization in further uncertainty propagation and quantification study for small-sized HTGR.