The evaluation of the damage ratio of spent nuclear fuel is a very important intermediate variable for dry storage risk assessment, which requires an interdisciplinary and comprehensive investigation. It is known that the pinch load applied to the cladding can leaded to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, the failure resistance of Zircaloy-4 cladding against the pinch load is investigated using numerical simulations assuming the existence of radial hydrides. The simulation model is based on the microscopic images of cladding. A pixel-based finite element model was created by separating the Zircaloy-4 and hydride using the image segmentation method. The image segmentation method uses a morphology operation basis, which is a preprocessing method through erosion operation after image expansion to enable normal segmentation by emphasizing pixels corresponding to hydrides. The segmented images are converted into a finite element model by assigning node and element numbers together with corresponding material properties. Using the generated hydride cladding finite element model, several numerical methods are investigated to simulate crack propagation and cladding failure under pinch load. Using extended finite element (XFEM) models the initiation and propagation of a discrete crack along an arbitrary, solution-dependent path can be simulated without the requirement of remeshing. The applicability of fracture mechanical parameters such as stress intensity, J-integral was also investigated.

항공기 충돌사고는 1970년대부터 원자력발전소의 인허가에 중요하게 고려되어 온 외부 사건의 하나였다. 9.11 테러 이후 세계 각국에서는 사고로 인한 항공기 충돌에 더하여 의도된 항공기 충돌에 대비한 안전성 평가를 수행해오고 있으며 일부 국가에서는 이를 법제화하여 인허가의 중요한 요건으로 다루고 있다. 항공기 충돌에 대한 안전성 평가는 여러가지 요인으로 인하여 쉽지 않은 작업이며 보다 신뢰성 있는 평가를 위한 연구개발이 세계 각국에서 진행 중이다. 본 논문에서는 각국의 항공기 충돌에 대비한 안전성 평가 요건의 법제화 현황을 사고로 인한 충돌과 의도된 충돌의 경우로 분리하여 정리하였다. 다 양한 조건의 항공기 충돌에 대한 안전성 평가를 위하여 수행되어 온 연구 중 주요한 것들을 정리하였으며 특히 사용후핵연 료 건식저장시설에 대한 내용을 위주로 다루었다.

This study shows the development of a photocatalytic technology for the road to decompose the nitrogen oxides(NOx) using a titanium oxide(TiO2) photocatalyst coating method for reducing the air pollution

Even though klotho deficiency in mice exhibits multiple aging-like phenotypes, studies using large animal models such as pigs, which have many similarities to humans, have been limited due to the absence of cell lines or animal models. The objective of this study was to generate homozygous klotho knockout porcine cell lines and cloned embryos. A CRISPR sgRNA specific for the klotho gene was designed and sgRNA (targeting exon 3 of klotho) and Cas9 RNPs were transfected into porcine fibroblasts. The transfected fibroblasts were then used for single cell colony formation and 9 single cell–derived colonies were established. In a T7 endonuclease I mutation assay, 5 colonies (#3, #4, #5, #7 and #9) were confirmed as mutated. These 5 colonies were subsequently analyzed by deep sequencing for determination of homozygous mutated colonies and 4 (#3, #4, #5 and #9) from 5 colonies contained homozygous modifications. Somatic cell nuclear transfer was performed to generate homozygous klotho knockout cloned embryos by using one homozygous mutation colony (#9); the cleavage and blastocyst formation rates were 72.0% and 8.3%, respectively. Two cloned embryos derived from a homozygous klotho knockout cell line (#9) were subjected to deep sequencing and they showed the same mutation pattern as the donor cell line. In conclusion, we produced homozygous klotho knockout porcine embryos cloned from genome-edited porcine fibroblasts.

To evaluate therapeutic efficacy of aldose reductase (AR) inhibition, the leaves of Aster yomena were tested for inhibition of AR. The stepwise polarity fractions of A. yomena were tested. Among them, the n-BuOH fraction showed highest activities against AR inhibition. Our results demonstrated that A. yomena could be a worthy natural source source for curing against diabetic complications.