Scholarly record

IMPACT ON THE NUCLEAR SAFETY OF THE 235U FISSION BY FAST NEUTRONS IN A THERMAL REACTOR

Н. Н. Ошканов

Abstract

Background. The issue discussed in this paper is caused by the historically established opinion that in thermal reactors the fission of uranium-235 by fast neutrons, which are formed during its fission by thermal neutrons, can be ignored. The purpose of the study is to assess the effect of the fission of uranium-235 by fast neutrons on the nuclear safety of a thermal reactor. Methods. For the study, the method of comparing fast neutron multiplication coefficients in the fission of uranium-235 by fast neutrons and without it is used and, on this basis, determination of the nuclear safety conformity to of a nuclear reactor. We used a multigroup method for estimating averaged neutron cross sections. Results. The main result of the work is the determination of the need to account for the fission of uranium-235 by fast neutrons in a thermal reactor, regardless of the enrichment of nuclear fuel of a thermal reactor by uranium-235 and the operating mode of the reactor (in a critical or subcritical state). Conclusion. To ensure nuclear safety of a thermal reactor in a subcritical state, the calculation of the multiplication factor on fast neutrons must be conducted either taking into account the fission of uranium-235 by fast neutrons, or using the derived formula for the correction factor without taking into account the fission of uranium-235 by fast neutrons.

Publication details

Back to publication list