A method of obtaining multi-group pn scattering matrix in reactor multi-group database

Abstract

A method for obtaining the multi-group Pn scattering matrix in the reactor multi-group database, based on the free gas scattering model, deriving through the formula and using the elastic scattering angle distribution data provided in the ENDF at a temperature of 0K during the derivation process, to obtain The expression σsn,T(E→E′) for the continuous energy Pn scattering matrix at temperature TK is derived, and based on the continuous energy Pn scattering matrix at temperature TK, the neutron moderation equation is solved to obtain the n-order medium Sub-flux density, and then calculate the multi-group Pn scattering matrix under the temperature TK through group calculation; the method of the present invention makes the multi-group Pn scattering matrix after group calculation more accurate, and finally improves the accuracy of resonance calculation in reactor physics calculation .

Description

technical field [0001] The invention relates to the field of nuclear reactor multi-group nuclear database and reactor physical calculation, in particular to a method for obtaining multi-group P in the multi-group nuclear database n Method of Scattering Matrix. Background technique [0002] In the numerical calculation of the reactor, the multi-group P n The scattering matrix (where n=0,1,2,...) plays a crucial role. Currently for multi-group P n Scattering matrix (where n=0,1,2,...), the traditional method is obtained by evaluating the nuclear database (hereinafter referred to as ENDF) through a series of processing. The biggest defect of this method is that it is aimed at elastic scattering. The elastic scattering reaction in the energy range below 200eV does not take into account the thermal motion of the target nucleus. With the gradual increase in reactor calculation requirements, the multi-group P given by the traditional method n The calculation method of scatteri...

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Problems solved by technology

[0039] This method is widely used, and this method is only for the continuous energy elastic scattering cross section σ s,T (E) The free gas model of the target nucleus has been dealt with, and the continuous energy P at the calculated temperature TK n Scattering matrix (where n=0,1,2,…) σ sn,T When (E→E′), it is considered that the target nucleus is at rest, which is inconsistent with the actual situation; at the same time, in the process of deriving the free gas model, the elastic scattering angle distribution under the 0K centroid system will be used, but the existing The derivation method assumes that the scattering angle is strictly isotropic (that is, f(E,μ)=0.5), which is inconsistent with the data given in ENDF

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