TY - JOUR AB - 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. VL - 15 IS - 8 SN - 0961-5539 DO - 10.1108/09615530510625084 UR - https://doi.org/10.1108/09615530510625084 AU - Pain C.C. AU - Gomes J.L.M.A. AU - Eaton AU - de Oliveira C.R.E. AU - Goddard A.J.H. PY - 2005 Y1 - 2005/01/01 TI - A model of heat transfer dynamics of coupled multiphase‐flow and neutron‐radiation: Application to a nuclear fluidized bed reactor T2 - International Journal of Numerical Methods for Heat & Fluid Flow PB - Emerald Group Publishing Limited SP - 765 EP - 807 Y2 - 2024/04/18 ER -