A model of heat transfer dynamics of coupled multiphase‐flow and neutron‐radiation

Abstract

Purpose -To present dynamical analysis of axisymmetric and three-dimensional (3D) simulations of a nuclear fluidized bed reactor. Also to determine the root cause of reactor power fluctuations. Design/methodology/approach -We have used a coupled neutron radiation (in full phase space) and high resolution multiphase gas-solid Eulerian-Eulerian model. Findings -The reactor can take over 5 min after start up to establish a quasi-steady-state and the mechanism for the long term oscillations of power have been established as a heat loss/generation mechanism. There is a clear need to parameterize the temperature of the reactor and, therefore, its power output for a given fissile mass or reactivity. The fission-power fluctuates by an order of magnitude with a frequency of 0.5-2 Hz. However, the thermal power output from gases is fairly steady.Research limitation/implications -The applications demonstrate that a simple surrogate of a complex model of a nuclear fluidised bed can have a predictive ability and has similar statistics to the more complex model. Practical implications -This work can be used to analyze chaotic systems and also how the power is sensitive to fluctuations in key regions of the reactor. Originality/value -The work presents the first 3D model of a nuclear fluidised bed reactor and demonstrates the value of numerical methods for modelling new and existing nuclear reactors.