A Method of Acquiring Intermediate Resonance Factors in Reactor Multigroup Nuclear Database

Abstract

A method to obtain the intermediate resonance factor in the multi-group nuclear database of the reactor. Based on the free gas model, the expression σr,s,T of the continuous energy neutron scattering matrix of the resonant absorbing nuclide at the temperature TK is derived through the formula (E→E′), and based on the continuous energy scattering matrix at temperature TK, solve the neutron moderation equation to obtain the neutron flux density at temperature TK, and then calculate the resonant absorption nuclide at temperature TK The multi-group absorption cross-section finally calculates the intermediate resonance factor through the intermediate resonance factor, and obtains the polynomial coefficient of the intermediate resonance factor with the temperature and the background section as independent variables through the least squares fitting method; the present invention makes the calculated intermediate resonance factor The intermediate resonance factor is more accurate, which improves the calculation accuracy and calculation efficiency of the intermediate resonance factor, and finally provides the accuracy and speed of the resonance calculation in the reactor physics calculation.

Description

Technical field [0001] The invention relates to the field of nuclear reactor multi-group nuclear database and reactor physics calculation, in particular to a method for obtaining intermediate resonance factors in the reactor multi-group nuclear database. Background technique [0002] In order to meet the requirements of high-fidelity resonance calculations for numerical reactors, it is important to provide accurate intermediate resonance factors in the multi-cluster database. [0003] At present, for the intermediate resonance factor, the intermediate resonance factor calculation method proposed in the internationally popular evaluation nuclear database processing program NJOY (hereinafter referred to as NJOY) is widely used. With the gradual increase in the requirements of reactor resonance calculation, many models of this method in calculating the intermediate resonance factor and the applicability of this method can no longer meet the requirements. [0004] The calculation method...

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Problems solved by technology

[0028] It can be seen from the above steps that this method will involve solving the neutron moderation equation, but the current traditional method when solving the neutron moderation equation, the model describing neutron elastic scattering is the progressive scattering kernel model, which ignores the resonant kernel The resonant upscattering of the element increases the resonant absorption, which leads to the inaccuracy of the calculated fine energy spectrum, further leads to the inaccuracy of the multi-group section, and finally makes the intermediate resonance factor inaccurate; on the other hand, from the above knowledge, the intermediate resonance factor It is a function of energy group, background cross-section, and temperature. In the calculation of full-reactor resonance, the background cross-section and temperature are constantly changing with the deepening of reactor burnup. This method can be used to continuously repeat the above steps according to the actual situation in the reactor. Online calculation Intermediate resonance factor, but slows computation time due to large full stack size

And if the scattering on the resonance is considered, the iterative method will be used to solve the moderating equation, which will also increase the calculation time sharply, which is extremely unfavorable for the calculation of the whole stack resonance

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