The domestic Pressurized Heavy Water Reactor (PWHR) nuclear power plant, Wolsong Unit 1, was permanently shut down on December 24, 2019. However, research on decommissioning has mainly focused on Pressurized Water Reactors (PWRs), with a notable absence of both domestic and international experience in the decommissioning of PHWRs. If proper business management such as radiation safety and waste is not performed, it can lead to increased business risks and costs in decommissioning. Therefore, the assessment of waste volume and cost, which provide fundamental data for the nuclear decommissioning process, is a crucial technical requirement before initiating the actual decommissioning of Wolsong Unit 1. Decommissioning radiation-contaminated structures and facilities presents significant challenges due to high radiation levels, making it difficult for workers to access these areas. Therefore, technology development should precede decommissioning process assessments and safety evaluations, facilitating the derivation of optimal decommissioning procedures and ensuring worker safety while enhancing the efficiency of decommissioning operations. In this study, we have developed a program to estimate decommissioning waste amounts for PHWRs, building upon prior research on PWR decommissioning projects while accounting for the specific design characteristics of PHWRs. To evaluate the amount of radioactive waste generated during decommissioning, we considered the characteristics of radioactive waste, disposal methods, packaging container specifications, and the criteria for the transfer of radioactive waste to disposal operators. Based on the derived algorithm, we conducted a detailed design and implemented the program. The proposed program is based on 3D modeling of the decommissioning components and the calculation of the Work Difficulty Factor (WDF), which is used to determine the time weighting factors for each task. Program users can select the cutting and packaging conditions for decommissioning components, estimate waste amount based on the chosen decommissioning method, and calculate costs using time weighting factors. It can be applied not only to PHWRs, but also to PWRs and non-nuclear fields, providing a flexible tool for optimizing decommissioning process.

With the aging of nuclear power plants (NPPs) in 37 countries around the world, 207 out of 437 NPPs have been permanently shutdown as of August 2022 according to the IAEA. In Korea, the decommissioning of NPPs is emerging as a challenge due to the permanent shutdown of Kori Unit 1 and Wolsong Unit 1. However, there are no cases of decommissioning activities for Heavy Water Reactor (HWR) such as Wolsong Unit 1 although most of the decommissioning technologies for Light Water Reactor (LWR) such as Kori Unit 1 have been developed and there are cases of overseas decommissioning activities. This study shows the development of a decommissioning waste amount/cost/process linkage program for decommissioning Pressurized Heavy Water Reactor (PHWR), i.e. CANDU NPPs. The proposed program is an integrated management program that can derive optimal processes from an economic and safety perspective when decommissioning PHWR based on 3D modeling of the structures and digital mock-up system that links the characteristic data of PHWR, equipment and construction methods. This program can be used to simulate the nuclear decommissioning activities in a virtual space in three dimensions, and to evaluate the decommissioning operation characteristics, waste amount, cost, and exposure dose to worker. In order to verify the results, our methods for calculating optimal decommissioning quantity, which are closely related to radiological impact on workers and cost reduction during decommissioning, were compared with the methods of the foreign specialized institution (NAGRA). The optimal decommissioning quantity can be calculated by classifying the radioactivity level through MCNP modeling of waste, investigating domestic disposal containers, and selecting cutting sizes, so that costs can be reduced according to the final disposal waste reduction. As the target waste to be decommissioning for comparative study with NAGRA, the calandria in PHWR was modeled using MCNP. For packaging waste container, NAGRA selected three (P2A, P3, MOSAIK), and we selected two (P2A, P3) and compared them. It is intended to develop an integrated management program to derive the optimal process for decommissioning PHWR by linking the optimal decommissioning quantity calculation methodology with the detailed studies on exposure dose to worker, decommissioning order, difficulty of work, and cost evaluation. As a result, it is considered that it can be used not only for PHWR but also for other types of NPPs decommissioning in the future to derive optimal results such as worker safety and cost reduction.

An assessment is made of the anti-proliferative activity of cicada slough-derived materials against 10 human cancer cell lines, including PC-3 and DU145 prostate cancer cell lines, using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Results were compared with those of the commercially available anticancer agent with broad spectrum cisplatin. The ethanol extract of Cryptotympana spp. slough was proved to have anti-proliferative activity against A549 lung, AGS stomach, PC-3 and DU145 prostate, Hela cervix, HT-29 colon, MCF-7 breast, and SK-Hep-1 liver cancer cell lines except for Hep-2 larynx and SK-OV-3 ovary cancer cell lines. The biologically active constituent was characterized as the nonprotein α-amino acid theanine [2-amino-4-(ethylcarbamoyl)butyric acid] by spectroscopic analysis, including EI-MS and NMR. Theanine was isolated from the cicada slough as a new cytotoxic principle. Fifty percent inhibition concentration (IC50) values of the constituent against PC-3 was 6.52 μg/mL, respectively. The activity of theanine (IC50,6.52μg/mL) did not differ significantly from that of the anticancer agent cisplatin (IC50,7.39μg/mL) toward PC-3. In conclusion, further studies on the cicada slough-derived materials containing theanine as potential anticancer products or a lead molecule for the prevention or eradication from human prostate cancer.

Lung cancer caused by diverse changes in cells resulted by exposure to carcinogens found in tobacco smoke, the environment, or sequential accumulation of genetic changes to the normal epithelial cells of the lung. An assessment was made of the anti-proliferative activity of constituents from silkworm feces against 11 human cancer cell lines, including A549 and H727 lung cancer cell lines, using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The ethanol extract of silkworm feces was proved to have anti-proliferative activity against all 11 species of human cancer cell lines. The biologically active constituent was characterized as vomifoliol (blumenol A) (1) and stigmasterol (2) by spectroscopic analysis ,including MS and NMR. In conclusion, global efforts to reduce the level of antitcancer agents justify further studies on the silkworm feces-derived materials containing vomifoliol and stigmasterol as potential anticancer products or lead compounds for the prevention or eradication from human lung cancer.