Continues-Energy Deterministic Neutron-Transport Calculation Method (2020.01- 2023.12)

The critical tool of nuclear reactor core neutronics analysis is the neutron-transport theory, for which the deterministic methods are widely employed by nuclear power engineering due to its high efficiency and low cost. However, the traditional multi-group approximation is still employed, causing two problems. (1) A neutron spectrum has to be assumed and employed during the multi-group nuclear data library production before knowing the exact definition of the calculation scenario. (2) The resonance self-shielding calculation has to be carried out to modify the microscopic cross sections with the spatial geometry and nuclide composition of the specific scenario, to consider the self- and cross-shielding effects and the nuclide interference effect. Consequently, in this project, a continues-energy deterministic neutron-transport calculation method, which has never been investigated before, is proposed to fully eliminate the multi-group approximation. It is planned to expand the smoothly continuous neutron flux in the non-resonance region, the probabilistic neutron flux in the unrecognized resonance region and the oscillatingly continuous neutron flux in the recognized resonance region by using proper orthogonal basis functions. The single- and bi-coupling relationships between different energy regions have to be carefully considered and the iterative strategies have to be designed. At the end, the entire methodology is planned to be verified and validated by using the measured data from active nuclear power plants. It is believed that this fundamental cutting-edge investigation will not only play a significant scientific role in developing neutron-transport theory, but also provide a better innovation perspective for nuclear-power software autonomy.

Research on the Key Techniques of Pin-by-pin PWR In-core Fuel Manangement Calculation (2018.01- 2021.12)

PWR in-core fuel management calculation provides pin-by-pin power distribution for safety and economy analysis of the corresponding reactor core by simulating the multi-physics coupling process including neutronics, thermal-hydraulics and nuclide depletion, et al. However, there are too more approximations in the current in-core fuel management calculation, which limits the safety and economic characteristics of the PWR reactor core through calculation accuracy. Consequently, based on the research foundation in our team, the pin-by-pin in-core fuel management calculation method, which is as the most possible next generation method, is proposed to be investigated mainly on its key techniques including: (1) heterogeneous leakage model for pin-by-pin homogenization, (2) pin-cell homogenized few-group constants parameterization, and (3) multi-physics coupling technique in three-dimensional whole core pin-by-pin calculation. Under the background of "Go Global" strategy, the research of this project is of important academic significance for the development and perfection of PWR core analysis theory, and is also a key step in the independent innovation of nuclear power softwares. Thus, it is a frontier basic research.