The legal status of Biodiversity Beyond National Jurisdiction (BBNJ) has been regulated through the High Seas Treaty as a common heritage of humankind. However, there still exist problems related to overlapping areas above the Extended Continental Shelf (ECS). In such areas, a significant continental shelf would fall within national jurisdiction, whereas the water column would be under the regime of the high seas, and BBNJ would be the common heritage of humankind. We argue that, in order to address the overlapping of areas within the superjacent waters in the ECS, a given sui generis status is required, so that the coastal state has a sovereign right to conserve the BBNJ in these areas. This study concludes that the sui generis arrangement should be implemented in the context of an overlapping ECS and its water column. The efforts of the Indonesian government to extend the continental shelf beyond 200 nautical miles constitute an important step in preserving natural resources for future generations.

This study explores the impact of metal doping on the surface structure of spent nuclear fuels (SNFs), particularly uranium dioxide (UO2). SNFs undergo significant microstructural changes during irradiation, affecting their physical and chemical properties. Certain elements, including actinides and lanthanides, can integrate into the UO2 lattice, leading to non-stoichiometry based on their oxidation state and environmental conditions. These modifications are closely linked to phenomena like corrosion and oxidation of UO2, making it essential to thoroughly characterize SNFs influenced by specific element doping for disposal or interim storage decisions. The research employs X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy to investigate the surface structure of UO2 samples doped with elements such as Nd3+, Gd3+, Zr4+, Th4+, and ε-particles (Mo, Ru, Pd). To manufacture these samples, UO2 powders are mixed and pelletized with the respective dopant oxide powders. The resulting pellet samples are sintered under specific conditions. The XRD analysis reveals that the lattice parameters of (U,Nd)O2, (U,Gd)O2, (U,Zr)O2, and (U,Th)O2 linearly vary with increasing doping levels, suggesting the formation of solid solutions. SEM images show that the grain size decreases with higher doping levels in (U,Gd)O2, (U,Nd)O2, and (U,Zr)O2, while the change is less pronounced in (U,Th)O2. Raman spectroscopy uncovers that U0.9Gd0.1O2-x and U0.9Nd0.1O2-x exhibit defect structures related to oxygen vacancies, induced by trivalent elements replacing U4+, distorting the UO2 lattice. In contrast, U0.9Zr0.1O2 shows no oxygen vacancy-related defects but features a distinct peak, likely indicating the formation of a ZrO8-type complex within the UO2 lattice. ε-Particle doped uranium dioxide shows minimal deviations in surface properties compared to pure UO2. This structural characterization of metal-doped and ε-particle-doped UO2 enhances our understanding of spent nuclear fuel behavior, with implications for the characterization of radioactive materials. This research provides valuable insights into how specific element doping affects the properties of SNFs, which is crucial for managing and disposing of these materials safely.

Heavy water (deuterium oxide, D2O) is water in which hydrogen atoms (1H, H), one of the constituent elements of water molecules, have been replaced with deuterium (2H, D), a heavier isotope. Heavy water is used in a variety of industries, including semiconductors, nuclear magnetic resonance, infrared spectroscopy, neutron deceleration, neutrino detection, metabolic rate studies, neutron capture therapy, and the production of radioactive materials such as plutonium and tritium. In particular, heavy water is used as a neutron moderator or coolant in nuclear reactors and as a fuel for nuclear fusion energy, methods for measuring heavy water are becoming increasingly important. There are methods with density, mass spectrometry, and infrared (IR) spectroscopy. In this study, Fourier transform infrared spectroscopy (FT-IR) was used, which is commonly used in IR spectroscopy because of its relatively high analytical sensitivity, low operating costs, and easy online analysis. Heavy water was identified in the range of 2,300-2,600 cm-1 wavenumber (O-D) and the range of 1,200-1,300 cm-1 wavenumber (D-O-D), which are known to be the range with strong infrared absorption. As a result, the linearity of infrared absorbance for each heavy water concentration was confirmed within the relative expansion uncertainty (k=2).

Most of the C-14 produced is in the organic form, generated as methane (14CH4), methanol (14CH3OH), formaldehyde (14CH2O), and formic acid (14CO2H2). When analyzing C-14, it is transformed into the form of 14CO2, and its concentration is determined using LSC. Typical examples include the wet oxidation method, the combustion or Pyrolysis. The wet oxidation method uses strong acids and involves repeated operations, which generates large amounts of acid waste and secondary radioactive waste. The combustion method uses high temperatures, which requires an oxygen device. Pyrolysis also requires high temperature in a vacuum and catalysts. Catalysts are expensive because they are platinum-based. To compensate for these shortcomings, a C-14 analysis method using UV irradiation was developed. In this study, 100 mL of distilled water mixed with formic acid (CO2H2), potassium persulfate (K2S2O8), and silver nitrate (AgNO3) was irradiated with a 320-390 nm UV lamp to conduct a CO2 production reaction experiment. The UV range was measured using a photometer (UV Power puck II). The beaker was made of quartz in 150 mL size with three inlets : a temperature measurement, a sample inlet, and a collection tube connector. We changed the UV lamp used from a 450 W halogen lamp to a 100 W LED, which has a lower temperature and is safer. As a result of the experiment, CO2 bubbles were generated in the collection tube, due to the UV irradiation react, which uses oxidizer and catalysts. The maximum temperature of the solution irradiated with the LED UV lamp was less than 56°C. It confirmed the rate of bubble generation changed depending on the lamp distance, the amount of sample, oxidizer, and catalyst. In an experiment to confirm the reaction caused by heat, it was found that although a reaction occurred due to heat, the reaction was significantly lower than when using a UV lamp. The reproducibility experiment was conducted three times in total under the same conditions. It showed the same pattern. In the future, we plan to select mock samples, collect 14CO2 in Carbo- Sorb, and analyze them using LSC. The results of this research will be used as a technology to recover C-14 more safely and efficiently and will also be used to expand its application to the treatment of other wastes such as waste liquid and waste resin through simulated samples.

Bis (2-ethylhexyl)phosphoric acid (HDEHP) is a renowned extractant, favored for its affinity to selectively remove uranium via its P=O groups. We previously synthesized HDEHP-functionalized mesoporous silica microspheres for solid-phase uranium adsorption. Herein, we investigated the kinetic and isothermal behavior of uranyl ion adsorption in mesoporous silica microspheres functionalized with phosphate groups. Adsorption experiments were conducted by equilibrating 20 mg of silica samples with 50 mL of uranium solutions, with concentrations ranging from 10 to 100 mgU L−1 for isotherms and 100 mgU L−1 for kinetics. Three distinct samples were prepared with varying HDEHP to TEOS molar ratios (x = 0.16 and 0.24) and underwent hydrothermal treatment at different temperatures, resulting in distinct textural properties. Contact times spanned from 1 to 120 hours. For x = 0.16 samples, it took around 50 and 11 hours to reach equilibrium for the hydrothermally treated samples at 343 K and 373 K, respectively. Adsorbed quantities were similar (99 and 101 mg g-1, respectively), indicating consistent functional group content. This suggests that the key factor influencing uranium adsorption kinetics is pore size of the silica. The sample treated at 373 K, with a larger pore size (22.7 nm) compared to 343 K (11.5 nm), experienced less steric hindrance, allowing uranium species to diffuse more easily through the mesopores. The data confirmed the excellent fit of pseudo-second-order kinetic model (R2 > 0.999) and closely matched the experimental value, suggesting that chemisorption governs the rate-controlling step. To gain further insights into uranium adsorption behavior, we conducted an adsorption isotherm analysis at various initial concentrations under a constant pH of 4. Both the Langmuir and Freundlich isotherm models were applied, with the Langmuir model providing a superior fit. The relatively high R2 value indicated its effectiveness in describing the adsorption process, suggesting homogenous sorbate adsorption on an energetically uniform adsorbent surface via a monolayer adsorption and constant adsorption site density, without any interaction between adsorbates on adjacent sites. Remarkably, differences in surface area did not significantly impact uranium removal efficiency. This observation strongly suggests that the adsorption capacity is primarily governed by the loading amount of HDEHP and the inner-sphere complexation with the phosphoryl group (O=P). Our silica composite exhibited an impressive adsorption capacity of 133 mg g-1, surpassing the results reported in the majority of other silica literature.

During the initial cooling period of spent nuclear fuel, Cs-137 and Sr-90 constitute a large portion of the total decay heat. Therefore, separating cesium and strontium from spent nuclear fuel can significantly decrease decay heat and facilitate disposition. This study presents analytical technique based on the gas pressurized extraction chromatography (GPEC) system with cation exchange resin for the separation of Sr, Cs, and Ba. GPEC is a micro-scaled column chromatography system that allows for faster separation and reduction volume of elution solvent compared to conventional column chromatography by utilizing pressurized nitrogen gas. Here, we demonstrate the comparative study of the conventional column chromatography and the GPEC method. Cation exchange resin AG 50W-X12 (200~400 mesh size) was used. The sample was prepared at a 0.8 M hydrochloric acid solution and gradient elution was applied. In this case, we used the natural isotopes 88Sr, 133Cs, and 138Ba instead of radioactive isotopes for the preliminary test. Usually, cesium is difficult to measure with ICP-OES, because its wavelengths (455.531 nm and 459.320 nm) are less sensitive. So, we used ICP-MS to determine the identification and the recovery of eluate. In this study, optimized experimental conditions and analytical result including reproducibility of the recovery, total analysis time and volume of eluents will be discussed by comparing GPEC and conventional column chromatography.

High-temperature molten salts not only demonstrate exceptional thermal and chemical stability but also offer significant advantages in catalyzing chemical reactions. Consequently, they have garnered attention as a promising medium for next-generation nuclear reactors and a wide range of electrochemical processes. Nevertheless, the challenging experimental conditions in molten salts make applying conventional analytical methods to understand reaction mechanisms a formidable task. This underscores the imperative need for more intuitive approaches to investigate molten salt chemistry. One of the simplest yet potent methods involves real-time visual monitoring of the reaction system as chemical reactions progress. In light of this, we have developed an experimental system enabling real-time visual monitoring of the internal dynamics of molten salt media. This system can capture high-resolution videos and images within molten salts, surpassing existing methodologies. We have applied this system in various electrochemical experiments using the molten LiCl-KCl eutectic salt medium. Among them, this study primarily focuses on two challenging experimental scenarios that became comprehensible through our proposed system’s application: (1) the transpassivation of Zr metal and the agglomeration of potassium hexachlorozirconate (K2ZrCl6) solid salt, and (2) the solvation of electrons during the oxidation of Li metal within the molten LiCl-KCl eutectic salt.

According to IAEA GSR Part.6, Decommissioning is carried out on the basis of planning and evaluation to ensure safety, protection of workers, public, and environment. Then, the decommissioning project of nuclear facility includes a radiation protection plan that reflects the regulatory requirements and international recommendations of each country and the internal regulations of the licensee. The scope of the radiation protection plan covers all radiation activities related to the dismantling and disposal of contaminated facilities subject to decommissioning. Radiation protection applications in the United States, a country with previous experience in decommissioning nuclear facilities, include 10 CFR 20 for NRC management facilities and 10 CFR 835 for facilities under DOE. In this study, we analyzed two cases of decommissioning plans to which NRC regulations are applied. In 1992, Yankee Atomic Electric Company (YAEC), the licensee of Yankee Nuclear Power Station (YNPS), notified NRC of the permanent shutdown of YNPS and submitted decommissioning plan accordingly. This decommissioning plan consists of a total of 9 chapters, and section 3.2 describes the radiation protection of decommissioning workers. The contents of the radiation protection program consist of 16 subsections. Another case is the decommissioning work plan of U.S. Navy Surface Ship Support Barge (SSSB), which used in Virginia to support the refueling of the U.S. Navy’s reactor vessel. This document was developed based on the NUREG-1757 and was revised in 2021 after receiving NRC comment. SSSB’s project radiation protection plan is described in appendix 1, and the contents consist of a total of 28 sections except for reference. In Korea, decommissioning plan is developed in accordance with “Standard Format and Content of the Decommissioning Plan for Nuclear Facilities”. According to this regulation, the radiation protection plan for licensing documents submitted at the time of application for approval of decommissioning execution shall describe the organization and functions for implementing of plan, methods, cycles and procedures for performing radiation protection and radiological monitoring. Also, the safety review guidelines of regulatory body also require radiation protection plans and procedures to ensure ALARA activities during decommissioning. In the case of the final decommissioning plan of Kori-1, which is currently submitted to regulatory body for licensing review, the decommissioning radiation protection plan is divided into 8 sections. Although the classification criteria for the radiation protection plan categories described above facilities are different, it could be seen that the following 7 contents are included in common: (a) ALARA application and organization for implementation, (b) Management of radiation control area, (c) Process of radiation work, (d) Radiation and contamination control, (e) Personnel radiation exposure monitoring, (f) Radioactive material management, (g) Radiation protection training.

Bisphenol-A, also known as BPA, is commonly used as a building block for epoxy and polycarbonate plastics. However, it has been recently identified as a major source of water pollution due to its release into the water from plastic products. BPA-based resins can also contaminate the water with high concentrations of BPA, which can enter the water bodies through production units and wastewater discharge. Photocatalysis, particularly the photo-Fenton process, is an effective method for wastewater treatment and degrading pollutants. Titanium dioxide (TiO2) is usually chosen based on its high photocatalytic properties and high performance. However, its wide band gap energy is a major issue for the photocatalytic process. This means that the catalyst can only exhibit high photocatalytic performance under UV-light irradiation and usually requires an acidic pH, which limits its use. In order to address the aforementioned issues, a visible-light photoactive photo-Fenton reaction has been successfully developed to degrade bisphenol A at natural pH using H2O2. The process was highly efficient, achieving complete degradation of phenol in just three hours of visible light irradiation with Cu-MOF. This environmentally friendly Fenton process has the advantage of occurring at natural pH levels with the presence of H2O2, providing a new perspective for efficient degradation. The photocatalyst was characterized using single X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), and UV–vis diffuse reflectance spectroscopy (DRS).

KHNP is conducting research to decommission Wolsong Unit 1 Calandria. Establishment of preparation and dismantlement processes, conceptual design of equipment and temporary radiation protection facilities, and waste management are being established. In particular, the ALARA plan is to be established by performing exposure dose evaluation for workers. This study aims to deal with the methodology of evaluating exposure dose based on the calandria dismantling process. The preparation process consists of bringing in and installing tooling and devices, and removing interference facilities to secure work space. The main source term for the preparation process is the calandria structure itself and crud of feeders. In the case of the dismantlement process, a structure with a shape that changes according to the process was modeled as a radiation source. It is intended to estimate the exposure dose by selecting the number of workers, time, and location required for each process in the radiation field evaluated according to the preparation and dismantlement process. In addition, it is also conducting an evaluation of the impact on dust generated by cutting operations and the human impact of C-14, H-3, which are specialized nuclides for heavy water reactors. KHNP is conducting an exposure dose evaluation based on a process based on the preparation and dismantlement process for decommissioning Calandria through computation code analysis. If additional worker protection measures are deemed necessary through dose evaluation according to this methodology, the process is improved to prepare for the dismantling of worker safety priorities.

Kori Unit 1 nuclear power plant is a pressurized water reactor type with an output of 587 Mwe, which was permanently shut down on June 18, 2017. Currently, the final decommissioning plan (FDP) has been submitted and review is in progress. Once the FDP is approved, it is expected that dismantling will begin with the secondary system, and dismantling work on the primary system of Kori Unit 1 will begin after the spent nuclear fuel is taken out. It is expected that the space where the secondary system has been dismantled can be used as a temporary storage place, and the entire dismantling schedule is expected to proceed without delay. The main equipment of the secondary system is large and heavy. The rotating parts is connected to a single axis with a length of about 40 meters, and is complexly installed over three floors, making accessibility very difficult. A large pipe several kilometers long that supplies various fluids to the secondary system is installed hanging from the ceiling using a hanger between the main devices, and the outer diameter of the pipe is wrapped with insulation material to keep warm. In nuclear secondary system decommissioning, it is very important to check for radiation contamination, establish and implement countermeasures, and predict and manage safety and environmental risks that may occur when cutting and dismantling large heavy objects. So we plan to evaluate the radiation contamination characteristics of the secondary system using ISOCS (In- Situ Object Counting System) to check for possible radioactive contamination. According to the characteristics results, decommissioning plans and methods for safe dismantling by workers were studied. In addition, we conducted research on how to safely dismantle the secondary system in terms of industrial safety, such as asbestos, cutting and handling of heavy materials and so on. This study proposes a safe decommissioning method for various risks that may occur when dismantling the secondary system of Kori Unit 1 nuclear power plant.