Sunghwan Yun

MONTE CARLO DEPLETION UNDER LEAKAGE-CORRECTED CRITICAL SPECTRUM VIA ALBEDO SEARCH

While the deterministic lattice physics/depletion codes use leakage-corrected critical spectrum (although approximate due to the B1 buckling search employed), Monte Carlo depletion codes currently in use do not have such a feature in spite of their heterogeneity and continuous-energy modeling capability. This paper describes an approach to Monte Carlo depletion with leakage-corrected critical spectrum derived from first principles. This is based on the concept of albedo eigenvalue treated as weight of the reflected neutron in Monte Carlo simulation.

A MONTE CARLO METHOD FOR SOLVING HEAT CONDUCTION PROBLEMS WITH COMPLICATED GEOMETRY

A new Monte Carlo method for solving heat conduction problems is developed in this study. Differing from other Monte Carlo methods, it is a transport approximation to the heat diffusion process. The method is meshless and thus can treat problems with complicated geometry easily. To minimize the boundary effect, a scaling factor is introduced and its effect is analyzed. A set of problems, particularly the heat transfer in the fuel sphere of PBMR, is calculated by this method and the solutions are compared with those of an analytical approach.

Overlapping Local/Global Iteration Framework for Whole-Core Transport Solution

Abstract In current practice of nuclear reactor design analysis, the whole-core diffusion nodal method is used in which nodal parameters are provided by a single-assembly lattice physics calculation with the zero net current boundary condition. Thus, the whole-core solution is not transport, because the interassembly transport effect is not incorporated. In this paper, the overlapping local/global iteration framework that removes the limitation of the current method is described. It consists of two-level iterative computations: half-assembly overlapping local problems embedded in a global problem. The local problem can employ heterogeneous fine-group deterministic or continuous-energy stochastic (Monte Carlo) transport methods, while the global problem is a homogenized coarse-group transport-equivalent model based on partial current–based coarse-mesh finite difference methodology. The method is tested on several highly heterogeneous multislab problems and a two-dimensional small core problem, with encouraging results.

GLOBAL DEPLETION ANALYSIS OF KOREAN HELIUM-COOLED SOLID BREEDER TBM MODEL FOR TESTING IN ITER

The Korean HCSB (Helium Cooled Solid Breeder) TBM (Test Blanket Module), whose breeding zone is composed of lithium ceramic, beryllium and graphite in pebble form, was designed based on LOCAL assumption. In this research, we establish a simple preliminary GLOBAL neutronics model for the Korean HCSB TBM and perform neutronics analyses including depletion (transmutation) calculation during 500EFPDs (Effective Full Power Days) using the modified MONTEBURNS code. The neutronics characteristics for D-D plasma phase are investigated in the preliminary GLOBAL neutronics model, and the results are compared with those of D-T plasma phase. Moreover, we also establish the A-lite based GLOBAL neutronics model for more reliable neutronics calculation, and the results are compared with each other.