Impact of mesh points number on the accuracy of deterministic calculations of control rods worth for Tehran research reactor

Abstract

In this paper two different computational approaches, a deterministic and a stochastic one, were used for calculation of the control rods worth of the Tehran research reactor. For the deterministic approach the MTR_PC package composed of the WIMS code and diffusion code CITVAP was used, while for the stochastic one the Monte Carlo code MCNPX was applied. On comparing our results obtained by the Monte Carlo approach and those previously reported in the Safety Analysis Report (SAR) of Tehran research reactor produced by the deterministic approach large discrepancies were seen. To uncover the root cause of these discrepancies, some efforts were made and finally was discerned that the number of spatial mesh points in the deterministic approach was the critical cause of these discrepancies. Therefore, the mesh optimization was performed for different regions of the core such that the results of deterministic approach based on the optimized mesh points have a good agreement with those obtained by the Monte Carlo approach.

Control rods reactivity worth calculation using deterministic and Monte Carlo approaches for an MTR type research reactor

“…Another research is done on the effect of spatial nodes on control rods reactivity worth using MCNPX code and MTR_PC package. Although its ability for acceptable justification of differences, it was not comprehensive [15]. So, because of the importance of reactivity worth of the control rods, the backbone of this research is focused on the detailed analysis of reactivity worth calculation using two different approaches and overcoming the discrepancies.…”