Preliminary neutronics analysis for generation III+ VVER design - VVER-1200

Abstract

The preliminary neutronics analysis of a new generation, first-of-its-kind VVER-1200 reactor has been carried out to develop an independent physics analysis capability that will support its future safety evaluations and licensing processes. An open-source Monte Carlo (OpenMC) code, utilizing LANL released ENDF/B-VIII.0 nuclear data, has been employed for this purpose. Initially, the validation of the lattice and core models of OpenMC simulations is established by comparing the effective neutron multiplication factor (Keff) estimated for a Normal Operating Condition (NOC) with the literature information. The comparison demonstrates that the prediction capability of the OpenMC code is on par with other international state-of-the-art codes. Once sufficient confidence is obtained in the modeling, the analysis is extended to investigate the inherent safety parameters, namely the reactivity coefficients of fuel and moderator temperatures, as well as the reactivity coefficient of boric acid concentration in the moderator at both the lattice (fuel assembly) and core levels. Behavioral changes of these parameters of interest, from the lattice to the core level, are examined and reported.