Wolsong Unit 1 is about 679 MW Pressurized Heavy Water Reactor (PHWR). Canada AECL was responsible for Nuclear Steam Supply System (NSSS) design and supply. Wolsong Unit 1 was operated from 1983 to 2019. Currently, Wolsong Unit 1 is under safety management after permanent shutdown. Wolsong unit 1, a heavy water reactor, has the following characteristics. • Unlike Light Water Reactor, vertical reactors, Heavy Water Reactor is installed horizontally. • The internal structure of the reactor is more complex than that of a light water reactor (380 pressure tubes in reactor as called Calandria) • The Calandria Vault, a large concrete structure filled with light water, is located outside of Calandria In the case of the decommissioning plan of PHWR in Canada, they have adopted a deferred decommissioning strategy that decommissioning begins after permanent shutdown and long-term safety management (30 to 40 years). So, Decommissioning of PHWR in Canada is expected to start in the 2050s. Nuclear Safety Act stipulates that if a commercial nuclear power plant is permanently suspended, the utility must submit a Final Decommissioning Plan (FDP) within 5 years. So, KHNP, the utility, is developing the FDP for Wolsong Unit 1 and have a plan to submit it to the government by the end of 2024. And then licensing review is expected to take at least two years. The key milestone for decommissioning project has a plan to start decommissioning in 2027 and complete it by 2034, but this is flexible depending of the government’s approval for decommissioning and the completion of prerequisites such as spent fuel transfer, etc. KHNP has prepared a strategy and system consisting of three areas such as R&D, Engineering and licensing document development to prepare the final decommissioning plan for Wolsong Unit 1. The promotion system for the preparation of the FDP for Wolsong Unit 1 is consisted of Engineering (HAS Characterization, Process/Work Package/Cost Estimation, Dismantling Safety Evaluation, Radiological Environmental Report, Radioactive Waste Treatment and Facility Construction), R&D (COG cooperation, KHNP R&D Results), Kori unit 1 lessons learned, etc. KHNP have the plan that the FDP Draft development by the end of 2023, reflecting engineering services results, R&D results, COG technical cooperation results and lessoned learned on Kori Unit 1. After collecting opinions from residents through a public hearing, the FDP will be submitted to the government by the end of 2024. It is expected that there will be many difficulties in the development process as it is the world’s first FDP development for the commercial Pressurized Heavy Water Reactors.

Disposal methods of radioactive waste can be mainly divided into near-surface disposal and deep geological disposal. If the radioactive waste is exposed to groundwater for a long time in the disposal environment, no matter how the decommissioning waste generated from the nuclear power plant is disposed of, the radionuclides may be released from the disposal site. Decommissioning waste from nuclear power plant contains radionuclides that are harmful to ecosystem including humans. Radionuclides released from disposal site behave in a complex and sensitive manner affected by geochemical conditions such as soil, geological media and groundwater. Sorption is one of the important mechanisms to retard the migration of radionuclides in a subsurface environment. In this study, geochemical properties of groundwater were collected and analyzed in the disposal environment considering disposal method in order to evaluate the geochemical behavior of radionuclides. The formation of aqueous and precipitated species of cesium and cobalt in a disposal condition were calculated and estimated. The sorption properties were also evaluated and predicted by considering the changes in the geochemical conditions such as pH, redox potential and geological media for the safety assessment.

Decontamination and Dismantlement (D&D) are of great interest to owner of decommissioning as a large number of old nuclear facilities around the world are either shutdown or soon to be decommissioned. D&D are key steps in the decommissioning of nuclear power plants (NPPs). These activities typically generate a significant volume of radioactively contaminated waste. However, as much as 90% or more of this waste is lightly contaminated metal and concrete that could potentially be cleared for recycle or beneficial reuse, rather than disposed of as radioactive waste. The objective of this study is to provide reference for the application of current technologies to cost-effectively reduce the volume of radioactive waste associated with decommissioning, through review of experiences with decontamination of NPPs materials for unrestricted release, recycle or reuse, Also, highlights the importance of ongoing efforts to harmonize regulations and standards for radioactive waste management globally to enable reuse and recycle of valuable materials generated during decommissioning. The presented results in the balance of this study are organized to align with the sequence of operations for executing reuse or recycle of material for a decommissioning project. Concrete from buildings has most commonly been used for backfill of voids onsite, while metal has most commonly been melted or cleared into the conventional scrap recycling industry. Copper and lead, commonly found in cables and shielding, have high residual value and are thus highly desirable for recycling. Steel and stainless steel, while not inherently valuable, are present in many large components, such that decontamination for recycling can be cost-effective compared to disposal as radioactive waste. The decontamination techniques range from simple, inexpensive methods to complex, aggressive methods, each with advantages in various scenarios and limitations in others. Treatment often involves the sequential application of two or more decontamination techniques (e.g., chemical decontamination followed by abrasive blasting). Strategies for the characterization of materials for recycling include analyzing material in place before dismantlement, analyzing removed samples before or after dismantlement, and evaluating bulk material removed after dismantlement. If clearance and recycling are permitted, metals can be released to the conventional scrap recycling market, and concrete rubble can be used as backfill material onsite. In general, successful reuse/recycle projects require consideration of reuse/recycling objectives and implementation of associated planning activities early in the decommissioning process. The practicality of reuse/recycle depends on a number of high level (country and region-specific) and component level (material and case specific) factors. Since this information is useful to those responsible for planning or implementing the decommissioning of nuclear facilities, it is expected that it will be of great help especially to those in charge of decommissioning plan and managers in charge of decommissioning projects.

Background: Individuals with scapular winging may have proprioceptive dysfunction which is important for motor control and causes shoulder instability. Reduced serratus anterior (SA) and lower trapezius (LT) muscle activity accompanied by over-active upper trapezius (UT), and pectoralis major (PM) may be contributing factors. Flexi-bar (FB) exercise may be used to increase joint position sense (JPS) and alter the target muscle activities. Objects: This study aimed to investigate the immediate effects of flexi-bar exercise prior to knee push-up plus (FPK) versus knee push-up plus (KPP) on JPS and muscle activity of SA, LT, UT, and PM in subjects with scapular winging. Methods: Eighteen subjects with scapular winging were recruited. JPS was investigated at baseline, after KPP and after FPK. Passive and active JPS errors were calculated by isokinetic equipment. Surface electromyography was used to record muscle activities during KPP and FPK. One-way repeated-measures analysis of variance and post hoc analyses were used to analyze the JPS error measured at baseline, after KPP and after FPK. Paired t-tests were used to compare muscle activities between KPP and FPK. Results: Passive JPS error was significantly decreased after KPP (p = 0.005) and after FPK (p = 0.003) compared to the baseline. Active JPS error was also significantly decreased after KPP (p = 0.016) and after FPK (p = 0.012) compared to the baseline. There was no significant difference in the passive and active JPS errors between KPP and FPK. SA activity during FPK was significantly increased (p = 0.024), and LT activity during FPK was significantly increased (p = 0.006). There were no significant differences in the UT and PM activity. Conclusion: FB might be recommended to immediately improve passive and active JPS and to selectively increase SA and LT muscle activities during KPP in individuals with scapular winging.