[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] It becomes important to manage adequately spent nuclear fuels (SNFs) for storage away from reactor and/or final disposal as the plant onsite capacity nearly reaches to saturation state. Although the Korean government has enacted relevant regulations and safety measures including several kinds of test for transport cask, a matter of interest should be extended to protect radioactive contents against accidents in conjunction with their future retrievability as well as transportability if necessary. The objective of this study is to demonstrate integrity of typical SNF rods in a developing dual purpose cask under six postulated 9 m free drop scenarios. At first, a series of finite element (FE) analyses of simplified spent fuel assembly (SFA) with external volume and equivalent mass were performed to find out the most severely damaged ones taking into account heavy computational cost. Subsequently, paired FE analyses were also carried out after detailed modeling of the selected SFA with fuel rods arrangement and practical material properties. Finally, structural integrity of the critical SNF rods was evaluated according to the vertical or oblique drop scenarios. The calculated maximum plastic strains at Zircaloy cladding were compared with specific failure criteria dependent on burn-up levels, of which engineering meaning and incorporated conservatism were discussed

[en] Yttria-stabilized zirconia (YSZ) films were deposited on (100) silicon wafers by a plasma-enhanced metallogenic chemical vapor deposition (PEMOCVD) process involving the application of vapor mixtures of bisdipivaloylmethanato yttrium, zirconium tetra-t-butoxide, and oxygen. From the X-ray diffraction (XRD) and transmission electron microscopy (TEM) results, the as-deposited YSZ films were found to be a single cubic phase and the preferred orientation of (100). Rutherford backscattering spectroscopy (RBS) and Auger electron spectroscopy (AES) analyses were performed to determine the Y₂O₃ mole percentage in YSZ films and this result was compared with that obtained by Aleksandrov model using the lattice constant by X-ray diffraction. The Y₂O₃ mole percentage in YSZ films obtained by AES and RBS showed a great deviations from those predicted by the Aleksandrov model

[en] The ubiquitin-proteasome system plays a central role in protein quality control through endoplasmic reticulum (ER)-associated degradation (ERAD) of unfolded and misfolded proteins. NF-E2‐related factor 2 (Nrf2) is a transcription factor that controls the expression of an array of phase II detoxification and antioxidant genes. Nrf2 signaling has additionally been shown to upregulate the expression of the proteasome catalytic subunits in several cell types. Here, we investigated the role of Nrf2 in tunicamycin-induced ER stress using a murine insulinoma β-cell line, βTC-6. shRNA-mediated silencing of Nrf2 expression in βTC-6 cells significantly increased tunicamycin-induced cytotoxicity, elevated the expression of the pro-apoptotic ER stress marker Chop10, and inhibited tunicamycin-inducible expression of the proteasomal catalytic subunits Psmb5 and Psmb6. The effects of 3H-1,2-dithiole-3-thione (D3T), a small molecule Nrf2 activator, on ER stress were also examined in βTC-6 cells. D3T pretreatment reduced tunicamycin cytotoxicity and attenuated the tunicamycin-inducible Chop10 and protein kinase RNA-activated‐like ER kinase (Perk). The protective effect of D3T was shown to be associated with increased ERAD. D3T increased the expression of Psmb5 and Psmb6 and elevated chymotrypsin-like peptidase activity; proteasome inhibitor treatment blocked D3T effects on tunicamycin cytotoxicity and ER stress marker changes. Similarly, silencing of Nrf2 abolished the protective effect of D3T against ER stress. These results indicate that the Nrf2 pathway contributes to the ER stress response in pancreatic β-cells by enhancing proteasome-mediated ERAD. -- Highlights: ► Nrf2 silencing in pancreatic β-cells enhanced tunicamycin-mediated ER stress. ► Expression of the proteasome was inducible by Nrf2 signaling. ► Nrf2 activator D3T protected β-cells from tunicamycin-mediated ER stress. ► Protective effect of D3T was associated with Nrf2-dependent proteasome induction.