Kori Unit 1, the first commercial nuclear power plant (NPP) in Korea, was permanently shut down in 2017 and was scheduled for decommissioning. Various programs must be planned early in the decommissioning process to safely decommission NPPs. Radiological characterization is a key program in decommissioning and should be a high priority. Radiological characterization involves determining the decommissioning technology to be applied to a nuclear facility by identifying the radiation sources and radioactive contaminants present within the facility and assessing the extent and nature of the radioactive contaminants to be removed from the facility. This study introduces the regulatory requirements, procedures, and implementation methods for radiological characterization and proposes a methodology to link the results of radiological characterizations for each stage. To link radiological characteristics, this study proposes to conduct radiological characterization in the decommissioning phase to verify the results of radiological characterization in the transitional phase of decommissioning NPPs. This enables significantly reducing the scope and content of radiological characterization that must be performed in the decommissioning phase and maintaining the connection with the previous phase.

본 연구는 작약의 품종간 개화시기 차이와 저온에서 장기 저 장이 가능한 품종을 선발하여 절화 유통 기간을 연장하기 위하 여 수행하였다. 작약 24품종을 대상으로 2022년 국립원예특작 과학원 시험포장에서 개화시기와 절화 품질을 조사하였다. 봉오 리 상태에서 수확한 작약을 건조 저장법으로 -1℃에서 60일 저장한 후 절화 수명과 절화품질을 조사하였다. ‘의성작약’은 홑 꽃이었고 나머지 품종은 겹꽃이었다. 개화시기는 5월 10일부터 18일 사이였으며, ‘Etched Salmon’, ‘Monsieur Jules Elie’, ‘Gilbert’, ‘Henry Bockstoce’는 개화일이 5월 10일로 가장 빨랐고, ‘Elsa Sass’는 5월 18일로 가장 늦었다. 식물체 키는 74.6∼107.8cm 였고, 절화 무게는 ‘Henry Bockstoce’ 품종 이 89.8g으로 가장 무거웠고, ‘Angel Cheeks’ 품종이 26.7g으 로 가장 가벼웠다. 꽃의 주된 색은 흰색, 빨강색, 분홍색, 자주색 이었다. -1℃에서 60일간 저장 후에 꽃과 잎의 상태가 아주 양 호한 품종은 ‘Kansas’, ‘Ole Faithful’, ‘Sonw Mountain’이 었다. 절화수명은 ‘Nick Shaylor’ 품종이 8일로 가장 길었고, 다음으로 ‘Blush Queen’, ‘Elsa Sass’ 품종이 7일이었으며, ‘Gilbert’, ‘Highlight’ 품종이 1일로 가장 짧았다. 작약은 저온 장기 저장에서 일부 품종을 제외하고는 꽃과 잎에 저온장해 증 상이 발생하였다. 이와같은 결과는 작약재배시에 품종 선택과 수확후 저온 장기 저장을 통하여 유통기간을 연장하고 하고자 할 때 기초자료로 활용될 수 있을 것으로 기대된다.

After the permanent shut down of Kori Unit 1, various decommissioning activities will be implemented, including decontamination, segmentation, waste management, and site restoration. During the decommissioning period, waste management is among the most important activities to ensure that the process proceeds smoothly and within the expected timeframe. Furthermore, the radioactive waste generated during the operation should be sent to a disposal facility to complete the decommissioning project. Square and cylindrical concrete re-package drums were generated during the 1980s and 1990s. The square, containing boron concentrates, and cylindrical, containing spent resin, concrete re-package drums have been stored in a radioactive waste storage building. Homogeneous radioactive waste, including boron concentrates, spent resin, and sludge, should be solidified or packaged in high-integrity containers (HICs). This study investigates the sequential segmentation process for the separation of contaminated and non-contaminated regions, the re-packaging process of segmented or crushed cement-solidified boron concentrate, and re-packaging in HICs. The conceptual design evaluates the re-packaging plan for the segmented and crushed cement-solidified waste using HICs, which is acceptable in a disposal facility, and the quantity of generated HICs from the treatment process.

Haemaphysalis longicornis는 사람과 동물에게 여러 심각한 병원체를 전달하는 주요 매개체로, 한반도에 널리 분포하고 있다. H. longicornis는 Rickettsia spp., Borrelia spp., Francisella spp., Coxiella spp., 그리고 중증열성혈소판 감소증후군 바이러스 (SFTS virus) 등을 매개하는 것으로 알려져 있다. 국내에 서식하는 H. longicornis의 미생물 군집과 관련된 연구는 많이 진행되지 않은 것으로 확인되었다. 이 연구는 한반도 내 다양한 지역에서 채집된 H. longicornis의 미생물군집 다양성을 지역별, 성장 단계 및 성별에 따라 분석하였다. 2019년 6월부터 7월까지 질병관리청 권역별기후변화매개체감시거점센터 16개 지역에서 채집한 H. longicornis의 16S rRNA 유전자 V3-V4 영역을 PCR로 증폭 후 Illumina MiSeq 플랫폼으로 시퀀싱하였다. Qiime2를 활용한 미생물 다양성 분석을 통해 총 46개의 샘플에서 1,754,418개의 non-chimeric reads를 얻었으며, 평균 126개 의 operating taxonmic unit (OTU) 을 식별하여 총 1,398개의 OTU를 확인하였다. 대부분의 지역에서 Coxiella spp.가 우점종으로 나타났으며, 특히 Coxiella endosymbiont는 가장 높은 우점도를 보이며, Coxiella burnetii와 계통 발생 학적으로 유사한 것으로 확인되었다. 이 연구를 통해 분석된 결과는 각 지역의 H. longicornis 미생물군집 데이터 베이스 구축에 활용되었으며, 이를 통해 지역별 미생물군집의 특이성을 식별할 수 있게 하였다. 이는 한반도의 H. longicornis에 의한 질병 전파 연구와 이를 통한 공중보건 개선에 기여할 것으로 기대된다.

본 논문에서는 빙하가 녹아 갈라져서 떠내려 온 새끼 펭귄이 다시 펭귄 무리로 되돌아가기 위 해서 길을 찾아 나서는 퍼즐 어드벤처 게임을 제안한다. 플레이어 40명의 로그 기록과 설문지 를 분석한 결과를 바탕으로 제안하는 게임의 특징을 살펴보고자 한다. 첫째, 제안하는 게임은 새끼 펭귄이 얼음 덩어리를 밀어서 길을 만들어 이동하는 직관적인 규칙을 제공한다. 로그 기 록에서 플레이 평균 시간은 19분이며, 이를 19개의 리스폰 지점으로 나누면, 구간별 플레이 평균시간은 1분이다. 설문에서 게임 목표 명확성은 4.45점, 게임 난이도는 4.16점을 받았다. 둘째, 제안하는 게임은 가마우지가 새끼 펭귄에게 도움말을 제시하는 등 유용한 정보를 친절 하게 제공한다. 전체 플레이 평균 시간은 baseline이 24분이고, kinder UI가 19분이다. kinder UI에서 새끼 펭귄이 얼음 덩어리를 덜 밀고, 게임 재시작을 덜 하고, 더 빨리 상호작 용하여, 문제를 빨리 해결한다. 설문에서 게임 스토리 이해는 4.15점, 유용한 정보는 4.45점을 받았다. 셋째, 제안하는 게임은 남극과 유사한 환경을 제공하여 몰입도를 상승시킨다. baseline에 비해서 kinder UI에서 다양한 게임 오브젝트와 더 적극적으로 상호작용을 시도하 고, 미션 완료 후 더 오랫동안 오로라를 지켜봤다. 설문에서 게임 캐릭터 선호도는 4.56점, 게 임 환경 만족도는 4.22점을 받았다.

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.

During the operation of nuclear power plant (NPP), the concentrates and spent resin are generated. They show relatively high radioactivity compared to other radioactive waste, such as dry active waste, charcoals, and concrete wastes. The waste acceptance criteria (WAC) of disposal facility defines the structure and property of treated waste. The concentrates and spent resin should be solidified or packaged in high integrity container (HIC) to satisfy the WAC in Korea. The Kori NPP has stored history waste. The large concrete package with solidified concentrates and spent resin. The WAC requires identification of 18 properties for the radioactive waste. Since some of the properties are not clearly identified, the large concrete packages could not satisfy the WAC in this moment. The generation of the large concrete package (rectangular type and cylindrical type), pretreatment of the package, treatment of inner drum, process development for clearance waste, etc. will be discussed in this paper. In addition, the conceptual design of whole treatment process will be discussed.

The solid-state chemistry of uranium is essential to the nuclear fuel cycle. Uranyl nitrate is a key compound that is produced at various stages of the nuclear fuel cycle, both in front-end and backend cycles. It is typically formed by dissolving spent nuclear fuel in nitric acid or through a wet conversion process for the preparation of UF6. Additionally, uranium oxides are a primary consideration in the nuclear fuel cycle because they are the most commonly used nuclear fuel in commercial nuclear reactors. Therefore, it is crucial to understand the oxidation and thermal behavior of uranium oxides and uranyl nitrates. Under the ‘2023 Nuclear Global Researcher Training Program for the Back-end Nuclear Fuel Cycle,’ supported by KONICOF, several experiments were conducted at IMRAM (Institute of Multidisciplinary Research for Advanced Materials) at Tohoku University. First, the recovery ratio of uranium was analyzed during the synthesis of uranyl nitrate by dissolving the actual radioisotope, U3O8, in a nitric acid solution. Second, thermogravimetric-differential thermal analysis (TG-DTA) of uranyl nitrate (UO2(NO3)2) and hyper-stoichiometric uranium dioxide (UO2+X) was performed. The enthalpy change was discussed to confirm the mechanism of thermal decomposition of uranyl nitrate under heating conditions and to determine the chemical hydrate form of uranyl nitrate. In the case of UO2+X, the value of ‘x’ was determined through the calculation of weight change data, and the initial form was verified using the phase diagram for the U-O system. Finally, the formation of a few UO2+X compounds was observed with heat treatment of uranyl nitrate and uranium dioxide at different temperature intervals (450°C-600°C). As a result of these studies, a deeper understanding of the thermal and chemical behavior of uranium compounds was achieved. This knowledge is vital for improving the efficiency and safety of nuclear fuel cycle processes and contributes to advancements in nuclear science and technology.