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.

Colorectal cancer causes the most cancer-associated death worldwide, having a high cancer incidence. Pectin is a complex polysaccharide present in various fruits, emerging as an anti-carcinogenic candidate. Although pectin has a suppressive capacity for colon carcinogenesis, the effect of reactive oxygen species (ROS) generation and colonic aberrant foci formation in the colon carcinogenesis mouse model remains unclear. Therefore, this study investigates the regulatory effect of pectin supplementation on colon carcinogenesis induced by azoxymethane (AOM) and dextran sodium sulfate (DSS) in mice. In an animal experiment, thirty male institute for cancer research (ICR) mice were divided into two experimental groups; AOM/DSS (control group) and AOM/DSS + pectin (5% in drinking water). Furthermore, the number of aberrant crypt foci (ACF) and aberrant crypt (AC) on colonic mucosa were counted, and thiobarbituric acid-reactive substances (TBARS) assay was performed to estimate lipid peroxidation in feces. Pectin treatment significantly decreased the number of ACF and AC per colon compared with the control. Additionally, fecal TBARS level in the pectin group was significantly lower than those in the control group. Conclusively, these findings indicate that pectin-inhibited hyperplastic alteration and oxidative stress suppress colitis-associated colon carcinogenesis.

Calcipex II has been widely used for root canal irrigation in endodontic treatment. It is a product of calcium oxide-based water soluble paste containing fine granular resin materials1). It was known that these granular materials were hardly dissolved in tissue and subsequently elicited foreign body granuloma by recruiting macrophages. Sometimes serious complications involving regional osteomyelitis and maxillary sinusitis were followed in long time after the endodontic treatment using Calcipex II materials2,3). And then the removed surgical specimen should be carefully examined to detect whether there exists Calcipex II material-related foreign body reaction or not. As the fine granular materials are too small in size, about 1 μm in diameter, and slightly translucent, it is difficult to find out the fine granular materials scattered throughout the granulomatous lesion even in the high magnification view. Here, we firstly found that the fine granular materials of Calcipex II showed bright birefringence under the polarizing microscope, and that the Calcipex II granules dispersed in chronic granulomatous lesion could be easily detected by their bright birefringence. The present study demonstrated a case of peri-implantitis involved with Calcipex II granule-related periapical granuloma, exhibiting numerous bright birefringence spots in the polarizing microscope observation.

In order to know the degenerating state of postnatal cleft lip tissue, total 23 cases of lip biopsy obtained from cleft lip surgery were collected and examined pathologically. The cleft lip tissues characteristically disclosed epithelial hyperplasia (13/23), stromal myxoid degeneration (20/23), salivary gland degeneration (1/23), muscular degeneration (11/23), and sebaceous gland hyperplasia (15/23), melanocytic infiltration (5/23). The epithelial hyperplasia was marked with hyperkeratosis and basal hyperplasia, which was usually coincident with the myxoid degeneration of underlying connective tissue. The myxoid degeneration was diffuse in the deep connective tissue with chronic inflammatoryreaction, and followed by extensive muscular degeneration. The sebaceous gland hyperplasia was usually predominant in the skin area of the cleft lip. In this study the lip biopsy from 30years old patient still showed remarkable retrogressive degeneration of lip tissue. Therefore, it is considered that the postnatal cleft lip tissue is continuously degenerative, and its retrogressive change gradually affects the deterioration of perioral muscular structures, consequently resulted in the failure of lip functions as well as further bizarre malformation of oro-facial shape during the postnatal period. These data also indicate that the biopsy of postnatal cleft lip should be recommended to know its variable degenerating status and to perform the proper rehabilitation surgery of cleft lip.