基于Dakota的燃料棒设计验证不确定度研究

燃料棒设计验证是评价燃料棒在反应堆内运行时安全性能的过程，其中输入参数的不确定度对评价结果有非常重要的影响。为了系统研究燃料棒设计验证的不确定度，使用Dakota中蒙特卡罗与拉丁超立方的非参数抽样方法，结合燃料棒性能分析软件开展了燃料棒设计验证计算，并与传统的不确定度计算方法进行了比较。结果表明，传统方法未充分考虑输入参数的不确定度，导致内压准则在正常运行条件下容易受到挑战，统计性的抽样方法弥补了这一缺陷，获得了较大的安全裕量，为燃料棒安全性以及经济性的提升提供了理论依据；同时，2种抽样方法所获得的燃料温度计算结果较传统方法更加具有参考意义；对于包壳腐蚀准则以及包壳应变准则，由于不确定度输入参数选取得当，抽样方法与传统方法的计算结果无明显区别。因此，基于非参数抽样的统计法对于评价燃料棒在反应堆内的安全性能更加具有实用性。

Uncertainty research of fuel rod design verification based on Dakota

Fuel rod design verification is the evaluation process of fuel rod safety performance during operation in reactor, in which the uncertainty of input parameters has important effect on evaluation results. To study the uncertainty systematically, fuel rod performance analysis software has been coupled with Dakota software to carry out fuel rod design verification, the results of nonparametric Monte Carlo and Latin Hypercube Sampling have been compared with those of traditional method. It turns out that the fuel rod inner pressure criterion is vulnerable to be under challenge for the reason of input uncertainty under consideration by traditional method. The defects can be made up by statistical nonparametric sampling, by which a larger safety margin is obtained, and a theoretical basis for fuel rod safety and economic performance enhancement is provided. Meanwhile, the temperature calculation result obtained by two sampling methods can be more referential compared with traditional method. For the cladding corrosion and strain criterion, the results of sampling methods and traditional method show no significant difference, for the reason that the uncertain input parameters are selected suitably. In conclusion, the statistical method based on nonparametric sampling can be more practically significant for safety performance evaluation of fuel rod in operation.