Host: The Japan Society of Mechanical Engineers
Name : The 30th International Conference on Nuclear Engineering (ICONE30)
Date : May 21, 2023 - May 26, 2023
Accurate cognition of the neutron reaction rule is an important guarantee of the safety and economy of nuclear power plant. Since the material composition and geometry configuration of the new type reactor has gradually become more complex, it brings severe challenges to the high-fidelity reactor physics calculation. The resonance self-shielding calculation provides effective cross section for the neutron transport and depletion calculation, so it is a key point in the reactor physics calculation. The precision of resonance selfshielding cross section is an important basis for analyzing neutron behaviors in the reactor. The subgroup method has relatively high efficiency and good geometry applicability, so it is commonly applied to commercial core analyzing programs. The accuracy of the subgroup method depends on the subgroup parameters, which are generated by fitting the multivariate equations based on the resonance integrals. Therefore, the definition method of resonance integrals greatly influences the accuracy of the subgroup method.
Conventional resonance integral is generated based on a series of homogenous systems consisting of resonant nuclide and moderator nuclide, which is called the homogenous integral. Heterogeneous resonance integral is another type resonance integral which is generated by typical heterogeneous pin or slab problems. The subgroup parameters could be calculated either by homogenous or heterogeneous resonance integrals. However, the influence of these two kinds of resonance integrals for subgroup resonance calculation is still not clear. Since the new type of reactor is getting more and more complex, it is necessary to carry out the research to evaluate this influence. In this work, both the homogenous and heterogeneous resonance integrals are generated to fit the subgroup parameters, and a series of problems are calculated to analyze the accuracy. The calculating results display the application range of each kind of resonance integral. Finally, the potential improving method is also discussed. Better accuracy of subgroup parameters could be achieved by adopting the improved fine group structure.
