ICONE23-1028 CHARACTERS OF COUPLED DYNAMICS IN MOLTEN SALT REACTOR WITH PERTURBATION THEORY

Abstract

In this paper, the time-dependent dynamic behavior of Molten Salt Reactor (MSR) is investigated by analyzing the dynamic response induced by a localized perturbation. Due to the small effect of the perturbation on the radial direction, the MSR is simplified as a one-dimensional system. To obtain more realistic case, the thermal feedback effect is taken into account. The theoretical models are established with the diffusion equations and the conservation equations for mass and energy. The group constants for various temperatures are processed with a HELIOS code to build the thermal feedback manner. Equations for fluctuations induced by perturbations are derived with linear perturbation theory. All the static and dynamic equations are solved numerically. The main conclusions are as follows. First, the assumption of a homogeneous system overestimates the effect of fuel circulation on the neutron flux distribution. Next, linear perturbation theory works well in large scope and can be regarded as an effective method to study the behavior of reactor noise. In addition, as the fuel velocity increases or the core height decreases, the reactor period becomes shorter and MSR quickly reaches the new steady state, indicating the stronger self-stabilization ability. Moreover, the Doppler reactivity feedback effect is dominated due to the absence of the graphite.