Wolsong unit 1, the first PHWR (Pressurized Heavy Water Reactor) in Korea, was permanent shut down in 2019. In Korea, according to the Nuclear Safety Act, the FDP (Final Decommissioning Plan) must be submitted within 5 years of permanent shutdown. According to NSSC Notice, the types, volumes, and radioactivity of solid radioactive wastes should be included in FDP chapter 9, Radioactive Waste Management, Therefore, in this study, activation assessment and waste classification of the End shield, which is a major activation component, were conducted. MCNP and ORIGEN-S computer codes were used for the activation assessment of the End shield. Radioactive waste levels were classified according to the cooling period of 0 to 20 years in consideration of the actual start of decommissioning. The End shield consists of Lattice tube, Shielding ball, Sleeve insert, Calandria tube shielding sleeve, and Embedment Ring. Among the components composed for each fuel channel, the neutron flux was calculated for the components whose level was not predicted by preliminary activation assessment, by dividing them into three channel regions: central channel, inter channel, and outer channel. In the case of the shielding ball, the neutron flux was calculated in the area up to 10 cm close to the core and other parts to check the decrease in neutron flux with the distance from the core. The neutron flux calculations showed that the highest neutron flux was calculated at the Sleeve insert, the component closest to the fuel channel. It was found that the neutron flux decreased by about 1/10 to 1/20 as the distance from the core increased by 20 cm. The outer channel was found to have about 30% of the neutron flux of the center channel. It was found that no change in radioactive waste level due to decay occurred during the 0 to 20 years cooling period. In this study, activation assessment and waste classification of End Shield in Wolsong unit 1 was conducted. The results of this study can be used as a basis for the preparation of the FDP for the Wolsong unit 1.

Background : This study was carried out to investigate the cytotoxicity in 9 extracts from 8 medicinal plants, such as leaf extract of Lonicera maackii (Llm), leaf extract of Platycarya strobilacea (Lps), flower extract of Fagopyrum dibortryis (Fdf), stem extract of Physostegia virginiana (Spv), root extract of Allium senescence (Ras), aerial part extract of Allium schoenoprasum (Aas), aerial part extract of Artemisia japonica var. manshurica (Aaj), stem extract of Caryopteris incana (Sci), and leaf extract of Caryopteris incana (Lci), on human cancer cell lines. Methods and Results : Dried plant extracts were granted from National Institute of Horticultural and Herbal Sciences. The extracts of each plant were dissolved in DMSO and stored in deep freeze at –20℃. The cell viabilities were examined by MTT assay. On SK-OV-3 cell line, Lps, Aas, Sci ans Lci showed dose-dependent cytotoxic effect. On A549 cell line, almost samples show dose-dependent cytotoxic effect, but especially Aaj showed relatively high cytotoxic effect. In case of HCT-15 cell line, Llm and Aas showed relatively high cytotoxic effect. Conclusion : These results suggested that Lonicera maackii, Platycarya strobilacea, Fagopyrum dibortryis, Physostegia virginiana, Allium senescence, Allium schoenoprasum, Artemisia japonica var. manshurica, and Caryopteris incana can be utilized as potential sources of anticancer agent due to their cytotoxicity.