[en] Spent nuclear fuel from nuclear reactors needs to be disposed of in isolation from humans and the environment as much as possible due to high heat and high radioactivity. Among the disposal methods of spent nuclear fuel, deep geological disposal, which is disposed of in the ground more than 500 m underground, is being considered as the most promising method. In the case of deep geological disposal, an engineered barrier is required to prevent radioactive material from leaking from the disposal container and spreading to the natural environment, and structural safety and criticality safety are required. In this study, to secure the structural safety of the disposal container and at the same time increase the handling efficiency, a study was conducted on a method of reducing the weight through structural change. During deep geological disposal, the critical safety evaluation of engineered barriers including the spent fuel copper disposal container was performed to calculate the interval among baskets for the spent fuel required for the design of the disposal cask. And by applying the analytical stress calculation method based on the beam theory, the efficient optimization of the cross-section of the disposal cask was performed. It was confirmed that a design that can have handling efficiency while securing structural and critical safety through the developed optimal design process can be secured

[en] We report our recent works on collisional-radiative modeling (CRM) for H/D plasmas and S/XB ratio analysis for measuring W sputtering yield in KAERI plasma beam irradiation facility (KPBIF). The KPBIF was constructed and has been developed for simulating heat and particle fluxes in divertor plasma by adopting the concept of applied field-magnetoplasma dynamic (AF-MPD) thruster. We has developed CRM for low temperature and density which solves nonlinear steady-state balance equations including processes such as radiation trapping and heavy particle collisions self-consistently. The CRM has been applied to H/D plasmas in the electron temperature range of 2 − 7 eV and the electron density range of 10¹¹ − 10¹³ cm⁻³ which are relevant to present KPBIF conditions. Particular attention has been paid to investigating sensitivities of line spectra intensities and densities of particles to used atomic and molecular data in the CRM. We used actual D reaction data for electron collision of D₂ molecule as well as D⁺₂ molecular ion collision of D₂ molecule [4], while some modelers used to replace e−H2 data for D plasma assuming the e−D₂ data is very similar to e−H₂ data. S/XB ratio for determine sputtering yield of W I has been measured in KPBIF and analysed by modelling using various atomic data on electron impact ionization/excitation and radiative decay. The details on available data and data needs for improving the analysis will be discussed. (author)