Burnup Calculation Method Study Based On Taylor Expansion And Truncation

Burnup calculation is an important part of reactor physics calculation.With the rapid development of nuclear energy science and computer simulation technology,burnup calculation and analysis are increasingly demanded,which brings greater challenges to burnup calculation methods and codes.The main purpose of burnup calculation is to predict how nuclide number densities change over time and by simulating the changes to analyze the influence of depletion on lifetime of reactor core,power distribution and reactivity control.The optimal fuel consumption depth and refueling scheme can be obtained through the burnup simulation calculation to reduce nuclear plants cost in actual projects,which has certain practical significance.The burnup equation is established according to the burnup chain of isotopes,and the solution of burnup equation is the core of the burnup calculation.In this paper,we investigate the prevailing burnup calculation methods which is divided into analytical method and numerical method according to the different treatments of burnup chain.After summarizing and analyzing the advantages and disadvantages of each method as well as their respective applicability,the point-depletion code is developed based on Taylor expansion and truncation method.Taylor expansion and truncation method solves burnup equation by separating the long and short life nuclides,reducing the rigidity of the burnup matrix,increasing the calculation accuracy and stability.The data of the point-depletion code of this paper is derived from commercial program HELIOS-1.11 database,which is based on the real pressurized water reactor and all of which data is sourced from the Evaluation Library ENDF / B-VI.Finally,this paper comprehensively verifies and analyzes the point-depletion code developed.First of all,this code is compared to the ORIGEN2 depletion solver under fixed irradiation conditions,and the results confirm the reliability of the method and code.Then,based on the coupling strategy of mature Prediction-Correction theory and Sub-step method,UO2 and MOX fuel cell and assembly cases in the JAEA benchmark are calculated by coupling with micro computing module of HELIOS program to test the accuracy of the point-depletion code.The results show that the results of the point depletion code is consistent with HELIOS program and reference results,which verifies the feasibility and accuracy of this code which can provide tool support for reactor core burnup calculation.