Spent Fuel Pool Island (SFPI) is a spent nuclear fuel storage pool that operates independently of existing nuclear facilities to safely manage SNF and minimize maintenance costs during the nuclear decommissioning process. Since the radiation controlled area can be dismantled before transporting SNF to a dry storage facility, the overall decommissioning period can be shortened, and the risk of occupational exposure during dismantling is reduced. In the US, various nuclear power plants have introduced SFPI for this reason. In this paper, to analyze the economic feasibility of application of SFPI to nuclear power plants to be decommissioned, several scenarios are established in consideration of the decommissioning plan and schedule, SFPI and dry storage facility application schedule. Cost and benefit list (SFPI application cost, SNF management cost, SNF dry storage cask cost, etc.) for each alternative were derived, and economic analysis was conducted by applying the Net Present Value (NPV). As a result of the analysis, it is found that the application of SFPI during decommissioning is economically effective as the NPV showed a positive number even when uncertainty was taken into account.

Reactive oxygen species (ROS) production and F-actin cytoskeleton dynamics play important roles in the survival rate of blastocysts after the vitrifiedwarming process. However, the protective effects of Mito-TEMPO against cryo-injury and viability through F-actin aggregation and mitochondrial-specific ROS production in vitrificated-warmed bovine embryos have not been investigated. The aims of the present study were to: (1) determine the effects of Mito-TEMPO on embryonic developmental competence and quality by F-actin stabilization during in vitro culturing (IVC), and (2) confirm the effects of Mito-TEMPO through F-actin structure on the cryotolerance of vitrification-warming in Mito-TEMPO exposed in vitro production (IVP) of bovine blastocysts. Bovine zygotes were cultured with 0.1 μM Mito-TEMPO treatment for 2 days of IVC. Mito-TEMPO (0.1 μM) exposed bovine embryos slightly improved in blastocyst developmental rates compared to the non-treated group. Moreover, the viability of vitrified-warmed blastocysts from Mito-TEMPO treated embryos significantly increased (p < 0.05, non-treated group: 66.7 ± 3.2% vs Mito-TEMPO treated group: 79.2 ± 5.9%; re-expanded at 24 hours). Mito-TEMPO exposed embryos strengthened the F-actin structure and arrangement in the blastocyst after vitrification-warming. Furthermore, the addition of Mito-TEMPO into the IVC medium enhanced embryonic survival and quality through F-actin stabilization after the vitrification-warming procedure. Overall, our results suggest that supplementing the culture with 0.1 μM Mito- TEMPO improves the embryonic quality and cryo-survival of IVP bovine blastocysts.

Vitrification methods are commonly used for mammalian reproduction through the long-term storage of blastocyst produced in vitro. However, the survival and quality of embryos following vitrification are significantly low compared with blastocyst from in vitro production (IVP). This study evaluates that the survival of frozen-thawed bovine embryos was relevant to mitochondrial superoxide derived mitochondrial activity. Here we present supplementation of the cryopreservation medium with Mito- TEMPO (0.1 μM) induced a significant (p < 0.001; non-treated group: 56.8 ± 8.7%, reexpanded at 24 h vs Mito-TEMPO treated group: 77.5 ± 8.9%, re-expanded at 24 h) improvement in survival rate of cryopreserved-thawed bovine blastocyst. To confirm the quality of vitrified blastocyst after thawing, DNA fragmentation of survived embryos was examined by TUNEL assay. As a result, TUNEL positive cells rates of frozenthawed embryos were lower in the Mito-TEMPO treated group (4.2 ± 1.4%) than the non-treated group (7.1 ± 3.5%). In addition, we investigated the intracellular ROS and mitochondrial specific superoxide production using DCF-DA and Mito-SOX staining in survived bovine embryos following vitrification depending on Mito-TEMPO treatment. As expected, intracellular ROS levels and superoxide production of vitrified blastocysts after cryopreservation were significantly reduced (p < 0.05) according to Mito-TEMPO supplement in freezing medium. Also, mitochondrial activity measured by MitoTracker Orange staining increased in the frozen-thawed embryos with Mito-TEMPO compared with non-treated group. These results indicate that the treatment of Mito-TEMPO during cryopreservation might induce reduction in DNA fragmentation and apoptosis-related ROS production, consequently increasing mitochondrial activation for developmental capacity of frozen-thawed embryos.