In order to improve the accuracy of photon heat release calculation for fast reactors,this paper studies the theory of high-precision photon cross-section production and the method of photon heat release calculation,and a library of photon cross-section related to the problem based on the self-developed photon cross-section processing code NGAMMA is generated.The cross-section library mainly includes neutron-photon ratio kinetic energy release(KERMA)factor,photo-atomic reaction cross-section,prompt photon production cross-section,delayed photon production cross-section and other data.The library is verified using the fast reactor benchmark problem ZPPR-9,and the computational results show that:(1)the computational accuracy of using the newly developed 94-group photon cross-section library to obtain the problem-related photon cross-section library by merging groups is significantly improved over the previous computational accuracy of directly generating the 21-group photon cross-section by utilizing NJOY.The relative deviation of the calculated results of photon heat release from the Monte Carlo results in the blanket region is reduced from-7.88％to less than 3％,and the relative deviation in the reflector region is reduced from 14.76％to 5.05％;(2)Consideration of delayed photon significantly affects the photon heat release,and compared with the consideration of prompt photon only,the consideration of delayed photon leads to an improvement of photon heat release in the inner and outer core regions by 33.11％;(3)The approximate calculation of the heat release of delayed photons by using the scaling factor method is in good agreement with the exact calculation results,and the relative deviation in each region is within±2％
Fast reactorPhoto cross sectionsNGAMMACoupled neutron and photonDelayed photon
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