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Introduction Nowadays multi-physics simulation attracts a lot of
attention from nuclear researchers worldwide since it is able to
produce more realistic results in terms of reactor core safety margins
against critical core conditions. The analysis of non-quantified
uncertainties on account of multi-physics phenomena involves the coupled
modeling of neutron kinetics, coolant thermal-hydraulics and nuclear
fuel performance using the numerical integration methods with built-in
precision and accuracy control. A new reactor core multi-physics
system has been developed to meet the control precision criterion and
to facilitate the transparency of the coupling procedure using the
external loose coupling approach. The new code implements an
adaptive time step to achieve a solution of a prescribed
tolerance, the restart capability to maintain sustainability of
numerical simulation, the random sampling method for uncertainty
quantification, and the lossy compression algorithm for output
data size optimization. The present configuration of the
multi-physics system addresses the two-step core neutronics
approach with a method-of-characteristic cross-section code and a
nodal diffusion solver aided by a pin-by-pin power reconstruction
module. Features Constituent Modules – Two-group cross-section library calculated by code STREAM – Two-group nodal diffusion code RAST-K 2.0 with pin-by-pin power reconstruction – Homogeneous two-phase coolant T/H code CTH1D – One dimensional fuel performance codes FRAPCON and FRAPTRAN Multi-physics Analysis – Reactor core depletion, transient and accidents simulation – Dynamical pellet-to-cladding gap heat transfer – Fuel swelling, densification, thermal expansion and relocation – Cladding creep, elastic and plastic deformations – Cladding hydrogen pickup and corrosion – Pellet-cladding mechanical interaction and cladding ballooning models Coupling interface – External loose coupling algorithm for interchangeable modules – Damped Picard iterations with Gauss-Seidel acceleration – Adaptive time step based on the step-doubling approach – Time step rejection and restart capability for robustness improvement Output Data Processing – High resolution multi-physics data – Storage in HDF5 format – PCA compression algorithm Uncertainty Quantification – Error propagation by random sampling – Nuclear data and core parameters uncertainties Application    |
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