Ulsan National Institute of Science and Technology · Engineering
Professor Deokjung Lee's research lab at Ulsan National Institute of Science and Technology (UNIST) specializes in computational reactor physics, with a focus on advanced nuclear reactor analysis, neutron transport, and core simulation. The lab develops high-fidelity simulation tools such as the STREAM and RAST-K codes for pressurized water reactors (PWRs), and applies these to whole-core depletion, resonance self-shielding, and advanced fuel cycle analysis. Research also extends to molten salt breeder reactors (MSBRs), where online reprocessing and equilibrium fuel cycles are modeled using MCNP6 and CINDER90. The lab emphasizes innovation in numerical methods, including improved resonance treatment, detector sensitivity modeling, and efficient iterative solvers for neutron diffusion problems.
Figures are computed from collected data and may differ slightly.
This paper presents the verification and validation (V&V) of the STREAM/RAST-K 2.0 code system for a pressurized water reactor (PWR) analysis. A lattice physics code STREAM and a nodal diffusion code RAST-K 2.0 have been developed by a computational reactor physics and experiment laboratory (CORE) of Ulsan National Institute of Science and Technology (UNIST) for an accurate two-step PWR analysis. The calculation modules of each code were already verified against various benchmark problem
The simulation of whole core depletion and continuous reprocessing of a molten salt breeder reactor (MSBR) was performed. The MSBR model was built using MCNP6, and the depletion and reprocessing simulations were modeled using CINDER90 and a Python script. The Python script was introduced to implement online reprocessing of molten salt fuel and the feeding of new fertile material with 3-day depletion intervals during the simulations. The simulation started with the reference composition from the
This paper reports on the development and verification of three new resonance self-shielding methods. The verifications were performed using the new neutron transport code, STREAM. The new methodologies encompass the extension of energy range for resonance treatment, the development of optimum rational approximation, and the application of resonance treatment to isotopes in the cladding region. (1) The extended resonance energy range treatment has been developed to treat the resonances below 4 e
A new calculational model of detector sensitivity, which is defined as the ratio of electric current to neutron flux, for self-powered neutron detector (SPND) is presented in this paper. Since Warren developed a sensitivity calculation model based on a multi-step analytic approach in 1972, there have been a lot of researches aimed at improving the accuracy of his model by partially employing Monte Carlo (MC) simulations in some of the calculation steps. However, there still exist assumptions suc
The huge absorption cross sections of 155Gd and 157Gd cause strong spatial shielding effects in Gd-bearing pins. A high-order depletion method has been developed for CASMO-5 to address the issue of the small depletion steps typically required for Gd-bearing fuel assemblies. In this method, the microscopic absorption reaction rates of gadolinium isotopes are assumed to be quadratic functions of the number density of 155Gd rather than the constant reaction rate assumption in the conventional predi
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