熔盐堆钍铀、铀钚燃料循环核数据不确定度分析

Uncertainty Analysis of Nuclear Data for Th-U and U-Pu Fuel Cycles in Molten Salt Reactor

反应堆物理设计不确定度是第4代核能系统的QMU(quantification of margins and uncertainties)有效性认证所必须的参数之一,核数据不确定度是其重要来源。基于自主开发的耦合程序BUND(burnup uncertainty of nuclear data),将SCALE程序TRITON和TSUNAMI-3D模块耦合,完成了熔盐堆钍铀燃料循环、铀钚燃料循环核数据引起的有效增殖因数keff不确定度分析,并与ENDF/B-Ⅶ.1协方差数据库计算结果进行了对比。结果显示:初始时刻,两种燃料循环模式下,核数据导致的keff不确定度分别为0.490%和0.582%。随燃耗的增加,核数据引起的keff不确定度增加。寿期末,两种燃料循环模式下,对keff不确定度影响显著增加的反应道分别为239Pu(nubar)、(n,f)、(n,γ)、105 Rh(n,γ)、135 Xe(n,γ)和234 U(n,γ)、143 Nd(n,γ)、131,135 Xe(n,γ)等。

Uncertainty of reactor physical design is one of the necessary parameters for the QMU（quantification of margins and uncertainties）validation of the Generation-Ⅳnuclear reactors,and uncertainty of nuclear data is an important source.Using BUND（burnup uncertainty of nuclear data）code to couple TRITON and TSUNAMI-3 D modules of SCALE code,calculations of uncertainties for the effective multiplication factorkeffin the molten salt reactor for Th-U and U-Pu fuel cycles were performed.The results were compared with the calculation results of uncertainty for keffby the covariance data from ENDF/B-Ⅶ.1.It is found that,at the beginning of life,the uncertainties for keff of Th-U and U-Pu fuel cycles are 0.490% and 0.582%,respectively,and they increase with burnup time.At the end of life,reaction channels 239 Pu（nubar）,（n,f）,（n,γ）,105 Rh（n,γ）,135 Xe（n,γ）and 234 U（n,γ）,143 Nd（n,γ）,131,135 Xe（n,γ）are significant for keffuncertainties of U-Pu and Th-U fuel cycles.