Method for calculating axial swelling effect of fast neutron reactor assembly

Abstract

The invention discloses a method for calculating an axial swelling effect of a fast neutron reactor assembly. The method comprises the following steps of 1, separating a transport computation grid from a burnup computation grid, wherein the transport computation grid is kept unchanged in the whole computation, and the burnup computation grid keeps growth of a same proportion along with axial swelling of a fuel assembly; 2, based on a variational nodal method, establishing a weak form of a neutron transport equation solution, wherein a section in a node is a function related to a spatial position, so that appearance of various materials is allowed in a transport computation node; 3, expanding a flux by utilizing a spherical harmonic function and a spatial orthogonal polynomial, and solving a flux expansion moment by adopting a response matrix method so as to obtain flux distribution of each node; and 4, calculating a burnup level of the node according to average power of a burnup node, obtaining a homogenized section of the burnup node according to burnup interpolation, and adjusting the homogenized section in the burnup node according to axial elongation of the assembly to obtain a required homogenized section in the computation node.

Description

technical field [0001] The invention relates to the technical field of nuclear reactor core design and safety, in particular to a method for calculating the axial swelling effect of fast neutron reactor components. Background technique [0002] Fast neutron reactors can convert fissile nuclides into fissile nuclides, greatly improving the utilization rate of uranium resources, which is of great significance to the sustainable development of nuclear energy. At present, fast reactors are still in the experimental and design stages, and accurate numerical simulations are essential for large-scale commercial use of fast reactors. [0003] Different from existing commercial pressurized water reactors, fast reactors usually use metal uranium-zirconium alloys as fuel in order to make the energy spectrum harder and obtain better breeding effects. Metal fuel has a large temperature expansion coefficient, and it is also prone to swelling and deformation when it is irradiated. In the...

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Problems solved by technology

[0004] Traditional methods of dealing with tine effects do not work well for axial swelling effects

First of all, the adaptive grid method will cause too fine grids in the core nodes, which not only greatly increases the calculation amount, but also makes it difficult for the node flux to converge

Calculating with the re-homogenization method requires the calculation of the homogenized cross-section for each node, which greatly increases the amount of calculation

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