Developing a full core model of the North Anna Reactor using SCALE 6.2.3, NESTLE and MCNP 6.2

Abstract

This study presents the development of the modelling for a T-NEWT/NESTLE* lattice-to-nodal diffusion calculation. The reactor selected for this study is the North-Anna (NA) Unit 1 Pressurized Water Reactor (PWR) of the Westinghouse design. Calculations are conducted at 300 K, at the beginning of Cycle (BOC). The NEWT code of the SCALE-6.2.3 (Standard Computer Analyses for Licensing Evaluation Version 6.2.3) package, is a multi-group discrete ordinate (deterministic) neutral-particle transport code that employs the Extended Step Characteristic spatial discretization method. NEWT is used to process and generate the homogenized-multigroup macroscopic cross-sections and other group constants for the NESTLE input file. The NESTLE code, embedded within the RELAP5-3D version 4.1.3 package, is a coupled multigroup (few-group) neutron diffusion reactor core simulator code that utilizes the nodal expansion method (NEM). The primary aim of this study was to develop a full core (FC) T-NEWT/NESTLE calculation input model for the NA PWR using the North-West University Reactor Code suite (NWURCS) developed at the North-West University, Unit for Energy and Technology Systems, as this neutronic to nodal diffusion (thermal-hydraulic) combination has not been tested at the North West University. The verification of NWURCS was achieved as the calculations between the manually generated T-NEWT models by the user with T-NEWT models generated by NWURCS were in good agreement. Furthermore, the results generated from the T-NEWT/NESTLE FC model were compared with a Monte Carlo full core calculation, using the Monte Carlo N-Particle radiation transport code version 6.2 (MCNP-6.2), which is equipped with a temperature-dependent ENDF/B-VII.1 cross section library. T-NEWT was used to obtain group constants and NESTLE and MCNP-6.2 was used to obtain the multiplication factor (keff). The efficiency of the T-NEWT/NESTLE code combination was achieved, as well as ‘the results for both approaches were found to be good agreement. * T-NEWT stands for the control module TRITON using NEWT. TRITON stands for Transport Rigor Implemented with Time-dependent Operation for Neutronic depletion code. NEWT stands for New ESC-based Weighting Transport code. NESTLE stands for Nodal Eigenvalue, Steady State Transient, Le core Evaluator code)