• International Journal of Safety
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• 제8권1호
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• pp.24-31
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• 2009

An effective assessment for decommissioning safety of nuclear facilities requires basic knowledge about possible risks, characteristics of potential hazards, and comprehensive understanding of the associated cause-effect relationships within a decommissioning for nuclear facility. This paper proposes an approach to develop the hierarchical structure and hazards of dealing with improving the complexity and uncertainty for decommissioning safety assessment of nuclear facilities and the resolutions are proposed to improve the complexity and uncertainty for decommissioning safety assessment of nuclear facilities. These resolutions can provide a comprehensive view of the risks in the decommissioning activities of a nuclear facility.

• 시스템엔지니어링학술지
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• 제14권1호
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• pp.63-71
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• 2018

This paper discusses decommissioning procedure requirements management using requirement engineering to systematically manage the technical requirements and criteria that are required in decontamination and decommissioning activities, and the regulatory requirements that should be complied with in a decommissioning strategy for research reactors and nuclear power plants. A schema was designed to establish the traceability and change management related to the linkage between the regulatory requirements and technical criteria after classifying the procedures into four groups during the full life-cycle of the decommissioning. The results confirmed that the designed schema was successfully traced in accordance with the regulatory requirements and technical criteria required by various fields in terms of decontamination and decommissioning activities. In addition, the changes before and after the revision of the Nuclear Safety Act were also determined. The dismantling procedure requirement management system secured through this study is expected to be a useful tool in the integrated management of radioactive waste, as well as in the dismantling of research reactor and nuclear facilities.

• 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.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.85-96
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• 2004

연구로 및 원자력 시설 해체작업 수행 시 고려해야 할 여러 가지 비용인자를 고찰하기 위하여 OECD 국가 및 원자력 선진국의 연구용 원자로 및 원자력 시설 해체비용에 대한 추정 결과의 영향 인자를 중심으로 분석하였다. 여러 가지 해체 비용을 유발하는 범주에서 원자력 시설 철거활동과 폐기물 처리 활동이 가장 많은 비용이 발생하는 것으로 예상되고 있고, 노동인력비용, 재료비 기타 비용 중에서 노동 인력 투입에 대한 비용이 가장 많이 차지한 것으로 나타났다. 해체비용에 영향을 미치는 주요 변수로는 Work difficulty, Regional labor cost 차이, Peripheral cost, Disposal/final burial costs으로 조사되었다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2003년도 추계학술대회 및 정기총회
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• pp.267-270
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• 2003

The quality assurance activities are important to obtain the safety and reliability in decommissioning of research reactor. It is essential to establish and implement effective quality assurance program. Foreign state-of-the-art standards and practices of quality assurance are investigated and analyzed to select quality assurance requirements. In this paper, guidelines are offered a suggestion to establish optimal the technology standard and lay out the managerial control scheme of quality assurance for decommissioning on research reactor.

• 한국방사선학회논문지
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• 제8권3호
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• pp.97-103
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• 2014

의료용 사이클로트론 해체시 많은 양의 저준위 방사성 폐기물을 발생시키며 이에 따른 큰 해체 비용을 야기한다. 이에 국외에서는 동위원소 생산시설 도입시 해체 자금에 관한 계획을 제출할 것을 권고하고 있다. 해체 자금 계획 수립을 위해서는 해체 비용을 해체 활동과 시설의 구성 요소에 맞게 합리적으로 계산되어야 한다. 본 연구에서는 2012년 12월 수행된 국내 서울대학교병원 사이클로트론(TR-13) 해체 사례를 통하여 폐기 시나리오일 때의 방사성 폐기물 처리 비용을 분석하고 해체 비용 산정시 필요한 고려사항에 대해 살펴보고 향후 해체 자금 계획 수립에 필요한 사항을 도출하고자 하였다.

• 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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• 제17권4호
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• pp.389-403
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• 2019

Large amounts of concrete waste are likely to arise from the decommissioning of a Kori-1 nuclear power plant. Several studies have been conducted on decommissioning concrete waste in recent decades, however, they have been limited to contaminated concrete issues or were small pilot-scale experiments. This study constructed two industrial-scale models of on-site concrete waste management for clean as well as contaminated concrete. To evaluate the performance of both the models, simulations were conducted using the Flexsim software. The concrete particle size distribution of Kori-1 and concrete processor properties based on widely used construction equipment were used as sources of input data for the simulations. It was observed that it may take over two years to complete the on-site concrete management processes owing to the performance of existing processors. In addition, it was demonstrated that it is essential to identify bottlenecks in the system and enhance the performance of the relevant processors to avoid delays of the decommissioning schedule. Our results suggest that this novel approach can contribute to developing schedules or expediting delayed activities in the Kori-1 decommissioning project.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1098-1108
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• 2019

Korea's first commercial nuclear power plant at Kori site was permanently shut down in 2017 and is currently in transition stage. Preparatory activities for decommissioning such as historical site assessment, characterization, and dismantling design are being actively carried out for successful D&D (Dismantling and Decontamination) at Kori site. The ultimate goal of decommissioning will be to ensure the safety of workers and residents that may arise during the decommissioning of nuclear facilities and, thereby finally returning the site to its original status in accordance with the release criteria. Upon completion of decommissioning, the resident's safety at a site released will be assessed from the evaluation of dose caused by radionuclides expected to be present or detected at the site. Although the U.S. commercial nuclear power plants with decommissioning experience use different site release criteria, most of them are 0.25 mSv/y. In Korea, both the unrestricted and restricted release criteria have been set to 0.1 mSv/y by the Nuclear Safety and Security Commission. However, since the dose is difficult to measure, measurable concentration guideline levels for residual radionuclides that result in dose equivalent to the site release criteria should be derived. For this derivation, site reuse scenario, selection of potential radionuclides, and systematic methodology should be developed in planning stage of Kori site decommissioning. In this paper, for calculation of a preliminary site-specific Derived Concentration Guideline Levels (DCGLs) for the Nuclear Power Plant site, a novel approach has been developed which can fully reflect practical reuse plans of the Kori site by taking into account multiple site reuse scenarios sequentially, thereby striking a remarkable distinction with conventional approaches which considers only a single site scenario.

• 방사성폐기물학회지
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• 제3권3호
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• pp.237-247
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• 2005

방사능에 오염된 시설물의 해체 작업은 예측할 수 없는 방사능의 출현으로 항상 사고의 위험성에 노출되어 있어 계획했던 해체 일정이 변경되어야 하고, 전체 공정의 재설계가 다시 수행되어야 하는 비경제적인 작업이 수없이 반복되고 있다. 해체 디지털 목업 시스템 설계에 필요한 구성인자들을 검토하였다. 조사된 단위 구성요소들은 해체 데이터베이스 시스템, 연구로 시설과 제염 및 해체 장비 모델링 시스템, 방사능 오염 분포도를 제작하는 3차원 방사화 매핑, 그리고 해체 일정을 평가하는데 기초가 되는 단위 작업별 평가식과 가중치 값 등이 있다. 독립적으로 운영되는 이들 구성 요인들을 통합된 시스템으로 만들기 위해 단위 시스템들에 대한 아키텍쳐 구현 연구가 수행되었다. 연구 결과 해체 디지털 목업 시스템을 통합된 환경에서 다양한 시나리오를 시험 평가할 수 있도록 하기위해 연구로 시설의 제염 및 해체 활동을 시각적으로 보여줄 수 있는 가시화(visualization) 모듈과 해체 일정 및 해체 비용을 평가 및 분석하는 시뮬레이션(simulation) 모듈로 구분하여 소프트웨어 아키텍쳐를 구현하였다.