Democratic People’s Republic of Korea (DPRK) has produced weapon-grade plutonium in a graphite-moderated experimental reactor at the Yongbyon nuclear facilities. The amount of plutonium produced can be estimated using the Graphite Isotope Ratio Method (GIRM), even without considering specific operational histories. However, the result depends to some degree on the operational cycle length. Moreover, an optimal cycle length can maximize the number of nuclear weapons made from the plutonium produced. For conservatism, it should be assumed that the target reactor was operated with an optimal cycle length. This study investigated the optimal cycle length using which the Calder Hall MAGNOX reactor can achieve the maximum annual production of nuclear weapons. The results show that lower enrichment fuel produced a greater number of critical plutonium spheres with a shorter optimal cycle length. Specifically, depleted uranium (0.69wt%) produced 5.561 critical plutonium spheres annually with optimal cycle lengths of 251 effective full power days. This research is crucial for understanding DPRK’s potential for nuclear weapon production and highlights the importance of reactor operational strategy in maximizing the production of weapons-grade plutonium in MAGNOX reactors.

Helicobacter pylori are known as a causative agent of gastritis, gastric duodenum and peptic ulcer, and gastric cancer, and multiple drug use is associated with various side effects in patients. The discovery of antibacterial substances against H. pylori from Korean resource plants is an important substitute for antibiotics. 52 species of Korean resource plants were collected and extracted with 50% ethanol, and antibacterial activity against H. pylori was measured using the disk diffusion method. The toxicity of plant extracts to human gastric adenocarcinoma(AGS) cells was measured by MTT assay, and the level of IL-8 secreted when gastric epithelial cells were inoculated with H. pylori was measured. As a result of measuring the antibacterial activity of H. pylori, antibacterial activity was confirmed in 38 plant extracts. The plant species with the strongest antibacterial activity were Chrysanthemum indicum, Rheum rhabarbarum, Patrinia scabiosaefolia and Petasites japonicus. C. indicum was not cytotoxic to H. pyroli-infected AGS cells and showed anti-inflammatory effects. This study's results can be used to develop healthy, functional foods and medical materials.

말라리아는 Anopheles 모기들에 의해 전파되며, 대한민국에서는 코로나 팬데믹 기간 동안(2020~2022) 약 200~300명대의 말라리아 환자가 발생하였으나, 지난 2023년에는 그 수가 폭증해 약 800명의 환자가 발생하였다. 현재까지 모기를 방제하기 위한 가장 효율적인 수단은 살충제를 사용한 방제이나, 지속적으로 이러한 화합물에 노출된 모기 개체군은 살충제에 저항성을 갖게 되는 것으로 알려져 있다. 이에 본 연구에서는 대한민국의 주요 말라리아 발생 지역인 비무장지대 부근 및 이외 지역인 용산, 평택, 오산에서 채집을 진행하였으며, 채집된 An. sinensis에 대해서 살충제 저항성과 관련되어 있다고 알려진 유전자인 acetylcholinesterase-1(ace-1)와 voltage-gated sodium channel(vgsc) 영역에 대한 저항성 돌연변이 보유 여부를 각각 확인하였다. 실험 결과 채집된 모든 지역에서 G119S(ace-1), L1014F,C(vgsc) 돌연변이가 발견되었으며, 그 빈도는 계절과 장소에 따라 차이를 나타내었다. 본 실험 결과는 향후 말라리아 감염 억제를 위한 매개체 연구에 활용될 수 있을 것으로 기대된다.

한강 3개 보 구간 수변부 11개 지점을 대상으로 2023년 총 2회 채집된 저서성 대형무척추동물은 총 100종 평균 426.0 개체/m2였다. 여주보에서 64종으로 가장 많이 출현하였고, 강천보에서 59종, 이포보에서 54종, 한강보상류 에서 41종, 한강보하류에서 32종이 확인되었다. 전체 평균 개체밀도는 강천보에서 944.1 개체/m2로 가장 많았고, 한강보상류에서 282.7 개체/m2, 여주보에서 251.9 개체/m2, 이포보에서 180.6 개체/m2, 한강보하류에서 172.9 개체 /m2 순으로 확인되었다. 한강 보 구간에서는 플라나리아류, 실지렁이, 깔따구류 등이 우점함. 보구간의 특성상 상대적으로 단순한 하상 및 깊은 수심에 적응성이 높은 실지렁이, 깔따구류의 우점은 일반적인 특성으로 볼 수 있으며 일시적으로 수변부에서 밀집된 플라나리아류의 채집이 이뤄져 우점된 결과를 보인 것으로 보임. 한강 보 구간 수변부 및 중앙부 조사지점별 군집분석을 실시한 결과 한강보 하류는 3개 보에 비해 우점도가 높고 다양도 와 풍부도가 낮았으며 전반적으로 상류부에 위치한 한강보상류 등의 지점에서 군집안정성이 확보되고 있는 것으로 보이며 이러한 점은 상대적으로 다양한 미소서식환경에 기인한 것으로 판단된다.

국내 원예작물에서 화분매개곤충의 의존도는 해마다 증가하고 있다. 우리는 사과, 딸기 등 화분매개곤충의 의존도가 높은 주요 과수와 시설작물에 대하여 화분매개곤충의 사용기술을 개발하고 이를 현장에 적용하는 연구를 수행하고 있다. 2021년부터 2022년까지 딸기, 키위 등 5가지 주요 농작물에서 화분매개벌을 적용한 결과, 딸기에서 뒤영벌의 적용결과 기존 꿀벌과 통계적으로 같은 수준의 화분매개효과를 나타내었으며, 하우스에서 농약적용시 하우스 밖으로 벌통을 위치시키는 것이 방치보다 벌의 소실을 20% 더 감소시킬 수 있었다. 인공수분 에 의존하고 있는 씨없는 수박에서 수분수 식재와 꿀벌을 이용함으로 기존 벌 방사보다 16% 착과율을 향상시킬 수 있었다. 시설고추에서 꿀벌과 뒤영벌의 혼합사용시 기존 꿀벌 방사보다 고추 수량이 10% 향상되었고, 토마토 에서 660㎡당 뒤영벌의 봉군량을 1.5배 증가시 토마토 수량은 4.4% 향상되었다. 키위는 꿀벌로 기존의 인공수분 을 충분히 대체할 수 있었고, 인건비가 60%이상 절감되었다. 또한 현재 시판중인 30종의 살충제와 27종의 살균제 에 대하여 24시간내 반수치사를 보인 농약은 각각 살충제 6종와 살균제 4종 이었다. 이어서 2023년부터 참외, 멜론, 사과, 단감에 대한 현장적용연구가 진행되고 있다.

Radioactive waste is typically disposed of using standard 200 and 320 L drums based on acceptance criteria. However, there have been no cases evaluating the disposal and suitability of 200 L steel drums for RI waste disposal. There has been a lack of prior assessments regarding the disposal and suitability of 200 L steel drums for the disposal of RI waste. Radioactive waste is transported to disposal facilities after disposal in containers, where the drums are loaded and temporarily stored. Subsequently, after repackaging the disposal drums, the repackaged drums are transported to disposal facilities by vehicle or ship for permanent disposal. Disposal containers can be susceptible to damage due to impacts during transportation, handling, and loading, leading to potential damage to the radiation primer coating during loading. Additionally, disposal containers may be subject to damage from electrochemical corrosion, necessitating the enhancement of corrosion resistance. Metal composite coatings can be employed to enhance both abrasion resistance and corrosion resistance. The application of metal composite coatings to disposal containers can improve the durability and radiation shielding performance of radioactive waste disposal containers. The thickness of radioactive waste disposal containers is determined through radioactive shielding analysis during the design process. The designed disposal containers undergo structural analysis, considering loading conditions based on the disposal environment. This paper focuses on evaluating the structural improvements achieved through the implementation of metal composite coatings with the goal of enhancing corrosion and abrasion resistance.

The development of existing radioactive waste (RI waste) management technologies has been limited to processing techniques for volume reduction. However, this approach has limitations as it does not address issues that compromise the safety of RI waste management, such as the leakage of radioactive liquid, radiation exposure, fire hazards, and off-gas generation. RI waste comes in various forms of radioactive contamination levels, and the sources of waste generation are not fixed, making it challenging to apply conventional decommissioning and disposal techniques from nuclear power plants. This necessitates the development of new disposal facilities suitable for domestic use. Various methods have been considered for the solidification of RI waste, including cement solidification, paraffin solidification, and polymer solidification. Among these, the polymer solidification method is currently regarded as the most suitable material for RI waste immobilization, aiming to overcome the limitations of cement and paraffin solidification methods. Therefore, in this study, a conceptual design for a solidification system using polymer solidification was developed. Taking into account industrial applicability and process costs, a solidification system using epoxy resin was designed. The developed solidification system consists of a pre-treatment system (fine crush), solidification system, cladding system, and packing system. Each process is automated to enhance safety by minimizing user exposure to radioactive waste. The cladding system was designed to minimize defects in the solidified material. Based on the proposed conceptual design in this paper, we plan to proceed with the specific design phase and manufacture performance testing equipment based on the basic design.

Prevention of radiation hazards to workers and the environment in the event of decommissioning nuclear power plants is a top priority. To this end, it is essential to continuously perform radiation characterization before and during decommissioning. In operating nuclear power plants, various detectors are used depending on the purpose of measurement. Portable detectors used in power plants have excellent portability, but there is a limit to the use of a single measuring device alone to quantify radioactive contamination, nuclide analysis, and ensure representation of measurement results. In foreign countries, gamma-ray visualization detectors are being actively used for operating and decommissioning nuclear power plants. KHNP is also conducting research on the development of gamma-ray visualization detectors for multipurpose field measurement at decommissioning nuclear power plants. It aims to develop detectors capable of visualizing radioactive contamination, analyzing nuclides, estimating radioactivity, and estimating dose rates. To this end, we are developing related software according to the development process by purchasing sensors from H3D, which account for more than 75% of the US gamma-ray visualization detector market. In addition, field tests are planned in the order of Wolsong Unit 1 and Kori Unit 1 with Research reactor in Gongneung-dong in accordance with the progress of development. The detector will be optimized by analyzing the test results according to various gamma radiation field environments. The development detector will be used for various measurement purposes for Kori unit 1 and Wolsong

Air conditioning facilities in nuclear power plants use pre-filters, HEPA filters, activated carbon filters, and bag filters to remove radionuclides and other harmful substances in the atmosphere. Spent filters generate more than 100 drums per year per a nuclear power plant and are stored in temporary radioactive waste storage. Plasma torch melting technology is a method that can dramatically reduce volume by burning and melting combustible, non-flammable, and mixed wastes using plasma jet heat sources of 1,600°C or higher and arc Joule heat using electric energy, which is clean energy. KHNP CRI & KPS are developing and improving waste treatment technology using MW-class plasma torch melting facilities to stably treat and reduce the volume of radioactive waste. This study aims to develop an operation process to reduce the volume of bag filter waste generated from the air conditioning system of nuclear power plants using plasma torch melting technology, and to stably treat and dispose of it. It is expected to secure stability and reduce treatment costs of regularly generated filter waste treatment, and contribute to the export of radioactive waste treatment technology by upgrading plasma torch melting technology in the future.

The stabilization technology for the damaged spent fuel is being developed to process the damaged fuel into sound pellet suitable for dry re-fabrication. It requires several treatments including oxidative decladding followed by reduction treatment for oxidized powder closely related to the quality of oxidized powders for pellet fabrication. For the development of operating condition for the reduction treatment, in this study, we evaluated the effect of air-cylinder based vertical shaking previously applied to oxidative decladding on powder reduction. For U3O8 of 50-100 g, the reduction test were applied with and without vertical shaking at 700°C under reduction atmosphere (Ar + 4%H2) and the concentration of hydrogen in effluent was measured to evaluate the reduction reaction. It was found that the vertical shaking system has allowed the reaction time of 50 g and 100 g U3O8 reduced by 33% compared to the test in static mode. Based on XRD analysis, the better crystallinity of the products was also achieved.

Bacterial phytopathogen Pectobacterium causes soft rot disease in several vegetable crops globally, resulting in heavy agricultural losses at both the pre and postharvest stages. The present work was carried out to screen Kimchi cabbage genetic resources conserved at the National Agrobiodiversity Center, Rural Development Administration, Korea, for resistance against the soft rot pathogen Pectobacterium carotovorum subsp. carotovorum KACC 21701 over a period of three years (from 2020 to 2022). Infection of the phytopathogen was carried out at four-leaf stage and for each accession, twenty-five plants per germplasm were infected with KACC 21701. Kimchi cabbage cultivars Wangmatbaechu, Seoulbaechu, and CR Kiyoshi were used as control. Seven-days post-infection, the Disease Index (DI) values were manually recorded from zero to four, zero matched perfectly heathy plants and four completely dead plants. The 682 accessions of Kimchi cabbage exhibited varying degrees of disease resistance to KACC 21701 and thirty accessions, exhibiting a DI≤2, were considered for replication studies. During the replication studies, four landrace germplasms (IT102883, IT120036, IT120044, and IT120048) and one cultivar (IT187919) were confirmed to be moderately susceptible to KACC 21701. Results of the preliminary screening as well as replication studies were documented for the all the 682 germplasms. Addition of such information to the passport data of stored germplasms might serve as potential bio-resource for future breeders and researchers to develop resistant varieties or study the mechanisms involved in resistance of plants to such phytopathogen.

The bacterial soft-rot disease is one of the most critical diseases in vegetables such as Chinese cabbage. The researchers isolated two bacteria (Pseudomonas kribbensis and Pantoea vagans) from diseased tissue samples of Chinese cabbages and confirmed them as being the strains that cause soft-rot disease. Lactic-acid bacteria (LAB), were screened and used to control soft-rot disease bacteria. The researchers tested the treatments with hypochlorous acid water (HAW) and LAB supernatant to control soft-rot disease bacteria. The tests confirmed that treatments with the HAW (over 120 ppm) or LAB (Lactobacillus plantarum PL203) culture supernatants (0.5 mL) completely controlled both P. kribbensis and P. vagans.