• 방사성폐기물학회지
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• 제4권4호
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• pp.385-391
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• 2006

연구용원자로 해체비용은 해체대상물에 대한 특성 및 제원에 맞게 해체작업을 분류하고 구성요소를 설정하여 단위비용인자를 바탕으로 한 공학적 비용 산정 방법으로 해체비용을 산정한다. 연구용원자로에 대한 해체비용은 크게 인건비, 장비 및 재료비로 구성이 되는데 해체작업에 소요되는 인건비는 해체대상물에 소요되는 작업시간을 바탕으로 계산을 한다. 본 논문에서는 연구용원자로 해체비용 산정 시 인건비 계산에 필요한 단위비용인자 및 작업 난이도 인자를 산출하였다.

• 방사성폐기물학회지
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• 제20권1호
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• pp.65-98
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• 2022

The nuclear legacy that remains in the United Kingdom (UK) is complex and diverse. Consisting of legacy ponds and silos, redundant reprocessing plants, research facilities, and non-standard or one-off reactor designs, the clean-up of this legacy is under the stewardship of the Nuclear Decommissioning Authority (NDA). Through a mix of prompt and delayed decommissioning strategies, the NDA has made great strides in dealing with the UK's nuclear legacy. Fuel debris and sludge removal from the legacy ponds and silos situated at Sellafield, as part of a prompt decommissioning strategy for the site, has enabled intolerable risks to be brought under control. Reactor defueling and waste retrievals across the Magnox fleet is enabling their transition to a period of care and maintenance; accelerated through the adopted 'Lead and Learn' approach. Bespoke decommissioning methods implemented by the NDA have also enabled the relevant site licence companies to tackle non-standard reactor designs and one-off wastes. Such approaches have potential to influence and shape nuclear decommissioning decision making activities globally, including in Korea.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.354-357
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• 2003

In decommissioning activities of nuclear facilities, the analyses and evaluations of data(man power, radiation exposure, waste outputs, equipments, etc ) is very important to accomplish effective decommissioning and dismantling. To handle the data from decommissioning activities of research reactor, we developed its database system. By using database system, we come to filter and analyze the date of decommissioning activities and we can evaluate the extraordinary decommissioning features of research reactor. It is likely to lay out and estimate the optimal plan of decommissioning. We expect that the database system of effective decommissioning activities build up the foundation of commercial reactor decommissioning.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1892-1900
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• 2023

A protective oxide layer forms on the material surfaces of a Nuclear Power Plant during operation due to high temperature. These oxides can host radionuclides, the activated corrosion products of fission products, resulting in decommissioning workers' exposure. These deposited oxides are iron oxides such as Fe₃O₄, Fe₂O₃ and mixed ferrites such as nickel ferrites, chromium ferrites, and cobalt ferrites. Developing a new chemical decontamination technology for domestic CANDU-type reactors is challenging due to variations in oxide compositions from different structural materials in a Pressurized Water Reactor (PWR) system. The Korea Atomic Energy Research Institute (KAERI) has already developed a chemical decontamination process for PWRs called 'HyBRID' (Hydrazine-Based Reductive metal Ion Decontamination) that does not use organic acids or organic chelating agents at all. As the first step to developing a new chemical decontamination technology for the Pressurized Heavy Water Reactor (PHWR) system, we investigated magnetite dissolution behaviors in various HyBRID inorganic acidic solutions to assess their applicability to the PHWR reactor system, which forms a thicker oxide film.

• 방사성폐기물학회지
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• 제19권3호
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• pp.387-419
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• 2021

The challenges facing companies and institutions surrounding civil nuclear decommissioning are diverse and many, none more so than those faced in the United Kingdom. The UK's Generation I nuclear power plants and early research facilities have left a 'Nuclear Legacy' which is in urgent need of management and clean-up. Sellafield is quite possibly the most ill-famed nuclear site in the UK. This complex and challenging site houses much of what is left from the early days of nuclear research in the UK, including early nuclear reactors (Windscale Piles, Calder Hall, and the Windscale Advanced Gas Cooled Reactor) and the UK's early nuclear weapons programme. Such a legacy now requires careful management and planning to safely deal with it. This task falls on the shoulders of the Nuclear Decommissioning Authority (NDA). Through a mix of prompt and delayed decommissioning strategies, key developments in R&D, and the implementation of site licenced companies to enact decommissioning activities, the NDA aims to safety, and in a timely manner, deal with the UK's nuclear legacy. Such approaches have the potential to influence and shape other such approaches to nuclear decommissioning activities globally, including in Korea.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3242-3249
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• 2022

As Kori unit 1 is undergoing the decommissioning process, estimating the disposal amount of waste from the decommissioned nuclear reactor has become one of the challenging issues. Since the waste disposal amount estimation depends on the packing of the waste, it is highly desirable to optimize the waste packing plan. In this study, we developed an efficient scheme for packing waste component segments. The scheme consists of 1) preparing three-dimensional models of segments, 2) orienting each segment in such a way to minimize the bounding box volume, and 3) applying hybrid genetic algorithm to pack the segments in the disposal containers. When the packing solution converges in the algorithm, it comes up with the number of containers used and the placement of segments in each container. The scheme was applied to Kori-1 reactor pressure vessel. The required number of containers calculated by the developed scheme was 24 compared to 42 that was the estimation of the prior packing plan, resulting in disposal volume savings by more than 40%. The developed method is flexible for applications to various packing problems with waste segments from different cutting options and different sizes of containers.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.1959-1965
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• 2023

The objective of this study was the establishment of clearance method that can ensure radiological safety and reasonably minimize radioactive waste when demolishing contaminated buildings at KRR-1&2. By reviewing Korean and international laws related to decommissioning, the method for clearance of contaminated buildings presented in this study is to first decontaminate the building and then conduct a radiological safety assessment, such as measuring residual radioactivity, to determine whether the radiation dose criteria for clearance are satisfied. The measurement results meet the radiation dose criteria, the contaminated buildings are regarded as clearance and can be converted into the general buildings. The demolition of the cleared buildings is carried out using conventional demolition methods. The waste generated during the demolition is classified as general construction waste and is disposed of according to relevant laws. The proposed method significantly optimized the number of samples analyzed and reduced the time and cost associated with the decommissioning. The established method will be applied to the ongoing decommissioning of contaminated buildings at KRR-1&2, and its application will be verified by regulatory bodies. The study suggests that this method could be used for the decommissioning of contaminated buildings at other Korean nuclear facilities in the future.

• Nuclear Engineering and Technology
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• 제43권6호
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• pp.583-592
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• 2011

The radiological characteristics for waste classification were assessed for neutron-activated decommissioning wastes from a CANDU reactor. The MCNP/ORIGEN2 code system was used for the source term analysis. The neutron flux and activation cross-section library for each structural component generated by MCNP simulation were used in the radionuclide buildup calculation in ORIGEN2. The specific activities of the relevant radionuclides in the activated metal waste were compared with the specified limits of the specific activities listed in the Korean standard and 10 CFR 61. The time-average full-core model of Wolsong Unit 1 was used as the neutron source for activation of in-core and ex-core structural components. The approximated levels of the neutron flux and cross-section, irradiated fuel composition, and a geometry simplification revealing good reliability in a previous study were used in the source term calculation as well. The results revealed the radioactivity, decay heat, hazard index, mass, and solid volume for the activated decommissioning waste to be $1.04{\times}10^{16}$ Bq, $2.09{\times}10^3$ W, $5.31{\times}10^{14}\;m^3$-water, $4.69{\times}10^5$ kg, and $7.38{\times}10^1\;m^3$, respectively. According to both Korean and US standards, the activated waste of the pressure tubes, calandria tubes, reactivity devices, and reactivity device supporters was greater than Class C, which should be disposed of in a deep geological disposal repository, whereas the side structural components were classified as low- and intermediate-level waste, which can be disposed of in a land disposal repository. Finally, this study confirmed that, regardless of the cooling time of the waste, 15% of the decommissioning waste cannot be disposed of in a land disposal repository. It is expected that the source terms and waste classification evaluated through this study can be widely used to establish a decommissioning/disposal strategy and fuel cycle analysis for CANDU reactors.

• 방사성폐기물학회지
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• 제14권2호
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• pp.123-134
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• 2016

최근 국내에서는 월성 1호기 및 고리 1호기를 포함하여 운영 중인 원자력발전소가 노후화함에 따라 원전 해체에 대한 관심이 많이 증대되고 있다. 이와 관련하여 월성 1호기의 계속운전이 최근 결정되었으며, 고리 1호기의 경우 2017년 6월 영구정지하기로 결정되었다. 이에 본 논문에서는 상업용 원자로로서는 국내 최초로 해체가 예정된 고리 1호기에 대해, 원자로 압력용기 자체의 해체로 인해 발생하는 방사성폐기물 최종 처분량을 원자로 압력용기 절단 방법 및 방사성폐기물 처분용기를 고려하여 산정하였다. 처분용기를 고려한 방사성폐기물 처분량을 산정한 결과 원자로 압력용기 몸통 부위보다는 반구 형태의 헤드 부분을 작게 절단할수록 최종 처분량이 감소하는 것으로 예측되었다. 또한 경주 방폐장의 200 L 및 320 L 드럼 처분용 처분용기의 경우 무게 제한으로 인해 적재효율이 좋지 못한 것으로 나타났다.

• Journal of Nuclear Fuel Cycle and Waste Technology
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• 제1권1호
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• pp.83-92
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• 2013

A novel methodology to evaluate remote dismantling equipment for a reactor pressure vessel (RPV) in a decommissioning project is presented in this paper. The remote dismantling equipment, mainly composed of cutting tools and positioning equipment, is absolutely required to cut and handle highly radioactive and large components in nuclear power plants (NPPs); this equipment has a great effect on the overall success of the decommissioning project. Conventional evaluation methods have only focused on cutting technologies or positioning equipment, although remote dismantling equipment cannot achieve its goal without organic interaction between the cutting tools and the positioning equipment. In this paper, the cutting tools and the positioning equipment are evaluated by performance parameters according to their original characteristics, the relationship between the two systems, and common factors. Finally, the remote dismantling equipment used in recent decommissioning projects has been evaluated based on the proposed methodology. The results of this paper are expected to be useful for future decommissioning projects.