物理学报2017，Vol.66Issue(1)：57-65,9.DOI:10.7498/aps.66.012801
抽样法与灵敏度法keff不确定度量化
Uncertainty quantification in the calculation of keff using sensitity and stochastic sampling method
摘要
Abstract
The sensitivity and uncertainty analysis (S/U) method based on the first order perturbation theory is commonly employed to calculate the uncertainties in-nuclear reactor's integral parameters,such as the neutron effective multiplication factor (keff),due to uncertainties in nuclear data.However,this method is only theoretically suitable for the linear model because of its first order approximation.Moreover,S/U method is difficult to incorporate into a neutronics code,because the adjoint angular flux is needed to obtain the sensitivity coefficient of an integral parameter to nuclear data.Meanwhile,the sampling approach based on parametric random sampling of input parameters,an easy implemented method,evaluates the uncertainties in the integral parameters by performing a set of neutronics simulations inputted with a set of stochastic nuclear data sampled from a multinomial normal distribution with nuclear cross section mean values and covariance data.The sampling approach is considered as a more exact method,as linear approximation is not needed.With the increase of computational power,the sampling methods with consuming more time are now possible.The sampling approach is incorporated into SURE,a sensitivity and uncertainty analysis code developed in IAPCM,as a functional module.A careful verification of the new function is necessary before it is used to analyze complicated problems,such as multi-physical coupling calculations of nuclear reactor.Two simple fast criticality benchmark experiments,namely Godiva (HEU-MET-FAST-001) and Jezebel (PU-MET-FAST-001),are selected to verify the sampling module of SURE.The uncertainties in nuclear data are given by multigroup covariance matrices processed from ENDF/B-Ⅶ.1 data.The uncertainties in the computed value of keff resulting from uncertainties in the nuclear data are calculated with both S/U and sampling methods.The uncertainties due to reaction cross sections for each nuclide in two benchmarks given by two methods with the multigroup covariance matrices are in good agreement.Since the S/U module of SURE code is verified extensively,the correctness of the sampling function of the code is confirmed as well.The distribution of the keff from the sampling approach obeys the normal distribution pretty well,which indicates that keff varies linearly with the nuclear data under its uncertainty range,since the nuclear data used in calculations are assumed to be normal distribution in the sampling method.The results from the sampling method also support the S/U method with linear approximation as a suitable uncertainty quantification method for keff calculation.关键词
不确定度量化/随机抽样法/灵敏度/核数据Key words
uncertainty quantification/stochastic sampling method/sensitivity/nuclear data引用本文复制引用
胡泽华,叶涛,刘雄国,王佳..抽样法与灵敏度法keff不确定度量化[J].物理学报,2017,66(1):57-65,9.基金项目
Project supported by the Key Laboratory of Neutron Physics of China Academy of Engineering Physics (Grant No.2013AA02),Sub-item of Special Project of the National Energy Bureau,China (Grant No.2015ZX06002008),National Magnetic Confinement Fusion Energy Research Project,China (Grant No.2015GB108002).中国物理研究院中子物理学重点实验室基金(批准号:2013AA02)、能源局06重大专项(批准号:2015ZX06002008)和国家磁约束核聚变能研究专项(批准号:2015GB108002)资助的课题. （Grant No.2013AA02）
