A Reduced Basis Approach for Modeling the Movement of Nuclear Reactor Control Rods

Abstract

This work presents a reduced order model (ROM) aimed at simulating nuclear reactor control rods movement and featuring fastrunning prediction of reactivity and neutron flux distribution as well. In particular, the reduced basis (RB) method (built upon a highfidelity finite element (FE) approximation) has been employed. The neutronics has been modeled according to a parametrized stationary version of the multigroup neutron diffusion equation, which can be formulated as a generalized eigenvalue problem. Within the RB framework, the centroidal Voronoi tessellation is employed as a sampling technique due to the possibility of a hierarchical parameter space exploration, without relying on a “classicalâ€‌ a posteriori error estimation, and saving an important amount of computational time in the offline phase. Here, the proposed ROM is capable of correctly predicting, with respect to the highfidelity FE approximation, both the reactivity and neutron flux shape. In this way, a computational speedup of at least three orders of magnitude is achieved. If a higher precision is required, the number of employed basis functions (BFs) must be increased.