Open AccessAssessment of the critical condition for the operation of an IBR reactor with a subcritical unit in an equilibrium mode
Author(s) -
Andrej Ivanovich Brezhnev,
A. V. Gulevich,
Oleg F. Kukharchuk,
Olga Fokina
Publication year - 2017
Publication title -
nuclear energy and technology
Language(s) - English
Resource type - Journals
ISSN - 2452-3038
DOI - 10.1016/j.nucet.2017.05.007
Subject(s) - delayed neutron , neutron , critical point (mathematics) , fission , physics , supercritical fluid , nuclear reactor , mechanics , control theory (sociology) , nuclear engineering , mathematics , nuclear physics , thermodynamics , mathematical analysis , computer science , engineering , control (management) , artificial intelligence
There considered a system consisting of a fast neutron batch pulsed IBR type reactor and a subcritical unit (neutronically thermal). The reactor is fitted with a reactivity modulator, which provides short-term “transfer” of the system from a deep subcritical to a prompt supercritical state and back. The system is in a deep subcritical state in the intervals between pulses.Such a system is capable to operate in an equilibrium (static) mode only when a critical condition is fulfilled for the kinetic parameters describing its operation.The neutron kinetics is described as part of a two-point approximation. It is assumed that the change in the reactor reactivity at the pulse generation time takes place periodically according to a parabolic law and the reactor is deeply subcritical in the intervals between pulses.Numerical simulation of the critical condition is extremely time-consuming, and analytical representation is almost impossible due to the need for solving ordinary differential equations with variable coefficients.There proposed a methodology for approximate estimating of parameters of a coupled “batch pulsed reactor–subcritical unit” system operating in an equilibrium mode. Analytical relations have been obtained in a quadrature form to calculate the “critical” condition of such a system in the approximation of “frequently recurring” pulses, when the decay of the delayed neutron precursors in the interval between pulses can be ignored.Calculations of the “critical condition” are illustrated by an example of a laser system consisting of an IBR-type batch pulsed reactor and a subcritical neutron multiplication unit, in which fission energy is converted into laser emission energy.Critical parameters of the system were estimated using analytical relations, as well as direct numerical calculations based on the STIK program that models the neutron kinetics in the considered system in a two-point approximation.It has been shown that the results of direct calculations and the estimates based on analytical relations matched good