28th Symposium of AER on VVER Reactor Physics and Reactor Safety (2018, Olomouc, Czechia)
Advances in spectral and core calculation methods
Rodolfo M. Ferrer, Joshua M. Hykes, Joel D. Rhodes (Studsvik Scandpower)
Studsvik has recently extended the CASMO5 advanced lattice physics code for the analysis of VVER 1000 and 1200 reactors. These extensions form the basis of CASMO5-VVER, which is primarily intended to compute homogenized nodal data for SIMULATE5-VVER. CASMO5-VVER leverages the latest nuclear data and numerical methods, developed for Pressurized Water Reactors (PWRs), to VVER analyses. The current CASMO5 data library, based on ENDF/B-VII.1 nuclear data evaluation, features a detailed 586 energy group structure and more than one thousand unique nuclides and materials. Resonance self-shielding, based on the Equivalence Theory and an Optimal Two-Term Rational (OTTR) method, has been extended to support hexagonal geometry. The solution to the two-dimensional transport equation over a single lattice, or alternatively multi-assembly domains, is based on the new Linear Source (LS) approximation for the Method of Characteristics (MOC), which supports mirror, periodic, and vacuum boundary conditions. The acceleration of the LS MOC solution is attained through the implementation of a Coarse-Mesh Nonlinear Diffusion (CMND) acceleration. Explicit tracking of actinides and fission products is made possible by a detailed description of burnup chains and the implementation of the Chebyshev Rational Approximation Method (CRAM), used for the solution to the Bateman system of equations. Results from preliminary validation against various critical experiments are presented in this work.