Validation And Application Of The Neutron Activation Calculation Code ABURN

Nuclear reactors produce a large number of high-energy neutrons during operation,and the materials inside the reactor will be activated by neutron irradiation and become radioactive,thus causing radiation damage to the staff.In order to accurately evaluate the neutron activation of materials,several neutron activation calculation programs have been developed at home and abroad,including the ABURN program developed by North China Electric Power University.According to the national guidelines for nuclear energy software development,the ABURN program needs to be fully tested and validated to ensure its calculation accuracy and engineering usability.In this paper,we conduct a validation study on the calculation method and calculation function of the ABURN program,and realize the application in the dose rate calculation of nuclear device shutdown.This paper first investigates the models and methods for neutron activation calculations,including the linear sub-chain method(TTA)and the Chebyshev rational approximation method(CRAM)used in the ABURN program.The linear chain benchmark problems(11 decay chains and 2 activation chains)published by UKAEA,the United Kingdom Atomic Energy Commission,were then selected to test and validate the calculation method of the ABURN procedure.The results show that the calculation results of the ABURN program for the linear chain benchmark problem are in good agreement with the analytical solution.In addition,based on the problem identified during the validation process that "the traditional CRAM method in the form of 14th-order PFD is limited in the selection of time steps for calculating the long-term decay of short-lived nuclides",the CRAM method in the form of higher-order IPF was introduced to enhance the inclusiveness of time steps.Subsequently,a comprehensive validation of the ABURN program was performed for the important calculation functions(atomic number,mass,activity,decay heat,photon energy spectrum,nuclide traces and contributions).Two IAEA benchmark calculations and 14 UKAEA benchmark calculations were selected and the results of the ABURN program were compared with the European activation program FISPACT-2007.The results show that the deviation of the ABURN program is basically within 1%for the above physical quantities and major nuclides,and the calculation results are accurate and reliable.In addition,the ABURN program is more outstanding than the FISPACT program in terms of nuclide trace tracing and contribution statistics.In nuclear devices,radionuclides produced by neutron activation of materials will continue to undergo decay reactions,and the high-energy photons produced by decay will pose radiation hazards to the staff,so the relevant shutdown dose rate for deactivation needs to be calculated and analyzed to ensure the personal safety of staff during the maintenance of nuclear devices.In this paper,based on the international mainstream strict two-step method(R2S),the coupled calculation interface module of the activation program ABURN and Monka program is developed to complete the automatic coupling of neutron transport calculation-neutron activation calculation-photon transport calculation;and realize the application of ABURN program in the shutdown dose rate calculation of nuclear device shutdown.In this paper,the fusion experimental device ITER-T426 and the pressurized water reactor HBR-2 unit were selected,the developed coupling program was used for modeling and shutdown dose rate deactivation calculation analysis,and the comparative evaluation of the calculation results was completed.The validation and application research work of this paper for the ABURN program enhances the usability of the ABURN program.The research results of this paper have certain theoretical research value and engineering application prospects.