Research On Uncertainty Calculation Of Neutron Activation Based On Direct Derivation Method

In the field of neutron activation calculation,due to the natural uncertainty of nuclear data,the calculation results are inevitably uncertain,which will have an important impact on the source term analysis and radiation shielding design of nuclear facilities,so it is necessary to calculate and analyze the uncertainty of neutron activation calculation accurately and efficiently.Based on the activation calculation program ABURN independently developed by the source term research group of nuclear facilities in North China Electric Power University,this paper first studies the reading method of nuclear data and its uncertainty in EAF-2010 open source data library,and then uses the direct derivation method in deterministic method to analyze the uncertainty of activation calculation,develops relevant program modules and selects typical examples to complete the test and verification.The calculation of neutron activation uncertainty needs nuclear data and its uncertainty as input parameters,which mainly come from nuclear data library.EAF2010 is the latest version in the EAF series of European activation data library,and it is open source published all over the world.In this paper,firstly,the storage content and storage format of EAF-2010 activation data library are studied,and the reading process and method of decay data library,cross section data library and cross section uncertainty data library are determined,and the read nuclear data are processed,including calculating decay daughter nuclide,collapsing cross section and calculating absolute uncertainty of cross section,finally,the developed EAF-2010 library reading function module is integrated into the activation calculation program ABURN.Compared with the sampling statistical method,the direct derivation method in the deterministic method has the advantages of accurate calculation results and high calculation efficiency,but it needs additional derivation and solution of the sensitivity coefficient equation.In this paper,firstly,the activation coefficient matrix and sensitivity coefficient matrix needed for uncertainty analysis are constructed based on the direct derivation method,finally,the sensitivity and uncertainty analysis module of nuclide inventory is developed based on the direct derivation method and Gear algorithm,and integrated into the activation calculation program ABURN.Then,four typical examples are selected for testing and verification.The results show that the calculated results of ABURN program for nuclide inventory,its sensitivity coefficient and relative uncertainty have little deviation from the analytical solution and the numerical solution of European activation program FISPACT,most of the deviation is less than 1%,and the maximum deviation is less than 2%,which shows that this method and program have the ability to analyze the sensitivity and uncertainty of nuclide inventory with high precision.The research work in this paper can provide tools and data support for radiation protection and source term analysis of nuclear facilities,and has certain theoretical methods and engineering practice value.