This article provides an analysis of the impact of asymmetrical assemblies homogenization and reflector modeling methods over the fission distribution, based on the first startup of the BEAVRS benchmark v2.0.2, in Hot Zero Power state (HZP). We use a classical two-step simulation with the deterministic codes DRAGON5 and DONJON5. First a transport calculation is performed with DRAGON5 on fuel assemblies, based on previous work conducted at the Polytechnique Montreal. Then, the complete core calculation is done with DONJON5 using a two-group energy mesh, in diffusion theory. The fission rates are calculated using DONJON5 and compared to the in-core detectors data provided in the BEAVRS benchmark. Discrepancies between the simulation and radial adjusted measurements present a Root Mean Square error (RMS) discrepancy of similar or equal to 4:5% (with relative errors lower than 10%). The results show the necessity to consider heterogeneity when it comes to model assemblies without central symmetry. (C) 2021 The Author(s). Published by Elsevier Ltd.

The IRSN code sequence based on DRAGON-5/DONJON-5 codes has been developed as part of the ORION project. Its goal is to provide a code sequence and computation scheme that works effectively for the study of PWR in operating conditions. The first part of the paper presents the differences between light and heavy reflectors and prove the need to validate the current computation scheme for heavy reflectors. The second part presents the validation of the DRAGON-5/DONJON-5 computation scheme by comparison of the relative power distribution with CA5MO-5 which is considered as the deterministic reference for the present study. The last part deals with the optimization of the computation scheme to improve the heavy reflector model. (C) 2018 Published by Elsevier Ltd.

This paper discusses the calculation of the IAEA benchmark entitled In-core fuel management code package validation for WWERs (IAEA-TECDOC-847) with the Version5 code system (DRAGON and DONJON). Calculations were performed for VVER-1000 cores. Cell calculations are done with DRAGON. Core calculations are done with DONJON, using CLE-2000 procedures to determine the reactor state at each depletion step, taking into account the control rod insertion pattern, reactor power, coolant inlet temperature and coolant mass flow. A multi-variate cross-section database for the core calculations is made with DRAGON. Calculated results are the critical boron concentration at each depletion step, and axial and radial power profiles at a few depletion steps. The present work serves as a feasibility study for the application of DRAGON and DONJON to VVER cores, and results are generally acceptable. Suggestions are made to improve the quality of the simulations.