Engineering Physics Annotation << Back Accurate Calculation of the Temperature Reactivity Effect of a Pulsed Reactor Verhoglyadov A.E., Verchoglyadova V.N., Vdovin Ya.A., Kushnir I.V. The work is devoted to the study of the influence of fuel expansion after a power pulse on the reactivity of the periodic pulsed reactor. The temperature of the fuel pellet is determined by solving a twodimensional non-stationary system of heat transfer equations. The equations are solved by different methods (numerical and analytical), the results are corresponding each other. The deformation of fuel pellets is determined using the fi nite element method in three-dimensional geometry. Monte Carlo neutronic calculations were performed in the full geometry of the reactor facility IBR-2M. For the fi rst time, it has been shown that the contribution of the fuel expansion reactivity of reactor demonstrates more complex time dependence if three-dimensional deformation of the fuel pellet is taken into account. The obtained data will serve as the basis for more accurate modeling of dynamic processes in a pulsed reactor. Keywords: nuclear reactors, nuclear fuel, core, reactivity, thermoelasticity, neutrons, feedback, instability, computational model. DOI: 10.25791/infizik.2.2026.1530 Pp. 03-09.