Title: Reactivity worth calculation for control rods groups of the VVER-1000 nuclear reactor core considering shadowing effect using Monte Carlo method

Authors: Zahra Tabadar; Gholam Reza Ansarifar; Kamal Hadad; Masoud Jabbari

Addresses: Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, Isfahan, Iran ' Department of Nuclear Engineering, Faculty of Advanced Sciences & Technologies, University of Isfahan, Isfahan, Iran ' Departments of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Fars, Iran ' Departments of Nuclear Engineering, School of Mechanical Engineering, Shiraz University, Shiraz, Fars, Iran

Abstract: Global core calculations use the diffusion equation to predict theoretically the nuclear reactor behaviour. However, this equation is not valid in strong absorbing media where the neutron spectrum is a rapidly varying function of the position, such as control rods or burnable poisons. In this paper, to overcome this misleading, the Monte Carlo simulation has been performed and the VVER-1000 reactor core in the MCL (Reactor Minimally Controlled Power Level) condition is modelled using the MCNPX code to calculate the reactivity worth of the control rod groups. The calculations in this model are divided into four steps. At first, the integral and differential worth are calculated for control groups 8, 9 and 10 with 50% overlapping and shadowing effect is considered. And in three other steps the integral and differential reactivity worths of control groups 8, 9 and 10 are calculated separately (without overlapping). In each step, the core is maintained critical by variation of the boron concentration. In these processes, the boric acid coefficient is achieved while the core is critical. The results are compared with experimental values and are in good agreement with them.

Keywords: control rod group; VVER-1000 nuclear reactor; Monte Carlo; reactivity worth calculation; MCNPX code; shadowing effect.

DOI: 10.1504/IJNEST.2019.103240

International Journal of Nuclear Energy Science and Technology, 2019 Vol.13 No.3, pp.274 - 294

Received: 05 Dec 2018
Accepted: 12 Aug 2019
Published online: 22 Oct 2019 *

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