atw - International Journal for Nuclear Power | 05.2019

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atw Vol. 64 (2019) | Issue 5 ı May DECOMMISSIONING AND WASTE MANAGEMENT 270 Guideline to Prepare a Preliminary Decommissioning Plan for Nuclear Facilities in Republic of Korea Byung-Sik Lee and Kyung-Woo Choi 1 Introduction The legal framework of decommissioning in Korea was enhanced through the revision of Nuclear Safety Act (NSA) and its subordinate status in 2015. According to the revised NSA, the nuclear power plant licensee should prepare the decommissioning plan (DP), i.e. preliminary DP, at the construction/operation stage of NPP. Additionally, the licensee should submit the DP, i.e. final DP, for approval of NPP decommissioning in Korea. In particular, the preliminary DP includes comprehensive implementation plans, maintenance of facility records, and physical and procedural methods to limit contamination and activation [1]. Therefore it is clear that the nuclear facility is considered for decommissioning in site selection, design, construction, commissioning and operation phases. The DP generally includes the decommissioning strategy including a relevant technical review report, to provide a justification for selecting a decommissioning strategy. The decom missioning cost is included in the DP, which is estimated based on the decommissioning activities of the nuclear facilities to be dismantled, and if necessary, a decommissioning cost estimate report should be attached. The DP also includes decommissioning schedules, decommissioning techniques, and manpower/ training programs. Most importantly, provisions on safety and radiation protection for population and workers are systema tically and deeply described [2]. To this end, the DP is divided into a preliminary DP and a final DP in accordance with the construction/ operation phase and decommissioning phase of the nuclear facility, respectively [1]. The details of the DP from the preliminary to the final plan are progressively described in detail. The most important factor in preparing the DP is to make full use of the design/construction/operation data of the nuclear facilities. The new nuclear facilities are subjected to a background survey of the site including the acquisition of environ mental information necessary for environmental impact assessment from the site selection stage. These data will be periodically revised until the decommissioning process, when practical, it should be helpful. Indeed, such site-related environmental information is used as a basis for defining the surrounding natural radiation of nuclear facilities and is used as a comparison to assess the environmental impact of dismantling nuclear facilities. However, if there is no background survey on the sur rounding environment at the nuclear facility construction stage, the site environmental survey is conducted during the operation of the facility. But, if there is not enough time to investigate further, similar area surveys are avail able. In the case of a new nuclear facility, a preliminary DP has to be prepared from its construction license stage and periodically revised until the final shutdown of the nuclear facility. The decommissioning operators include the appropriateness of decommissioning method, the appropriateness of decommissioning cost, the appropriateness of decommis sioning resources, the method of decommissioning safety evaluation, and the decommissioning waste management plan [3]. The preliminary DP can clearly show that important records related to decommissioning, such as facility design data, design data change history, and operation records, are maintained in accordance with the procedure throughout the life of the nuclear facility. According to the NSA, the preliminary DP should be revised periodically every 10 years in consideration of operation experience, lessons of decommissioning similar facilities, new safety requirements or revised safety requirements related with decommissioning, development trends of selected decommissioning strategies and related decommissioning technologies, and so on. The purpose of this paper is to provide the guideline how to prepare the preliminary DP in view of safety considerations based on the experience of nuclear facility decommissioning in major foreign countries. 2 Considerations to prepare a preliminary decommissioning plan The preliminary DP must be sub mitted at the time of applying for the operating license of the new nuclear facilities. Therefore, there is a limit to the depth of the technical contents of each item in comparison of the final DP. However, the preliminary DP should include the expected decommissioning strategy, appropriateness of decommissioning method, calculation of decommissioning cost, assurance of decommissioning finance, decom missioning safety and radiation protection plan, and decommis sioning waste management plan. Also, since the most important inputs to the DP are the design/ construction/operation data, the plan should describe how these records are maintained in accordance with relevant quality assurance programs for important records related to decommissioning over the life span. That is, design data of nuclear facilities, design data change history, operating records, etc. should be described in the preliminary DP [3, 4]. In the preliminary DP, considerations are given to the following items by referring to the results of the decommissioning pre-feasibility study at the engineering stage of nuclear facilities, the design specification of facilities, and the previous decommissioning experience data at home and abroad. pp Final goal of the decommissioning and application criteria and standards. pp Management of spent fuel and decommissioning waste. pp Analysis of critical path activities in disassembly scenario. pp Disclosure important factors in the decommissioning project management. 3 Identification of contents in a preliminary decommissioning plan 3.1 Management of design, construction and operation record Data on design, construction and operation experience necessary for Decommissioning and Waste Management Guideline to Prepare a Preliminary Decommissioning Plan for Nuclear Facilities in Republic of Korea ı Byung-Sik Lee and Kyung-Woo Choi
atw Vol. 64 (2019) | Issue 5 ı May decommissioning activities should be systematically managed and used as basic data for DP [3]. The list of necessary data for each step of the facility life span is as follows. pp Design/construction data management pp Management of changes to all structures, systems and components (SSCs) using Configuration Management System (CMS) pp Track design considerations to increase easy decommissioning activity pp Information on underground pipes and components in the site pp Startup/operation record management pp Modification data management of SSCs during the facility operation using CMS pp Management of incident/accident data during the facility operation pp Knowledge management related with operation experience pp Basic site characteristics data through sampling pp Operational waste information pp Information on spent fuel pp Location and characteristics of contaminated material release pp Existing internal/external stake holders communication related materials Therefore, the decommissioning operator should provide the details of how to document and manage the contents of the preliminary DP during the operation of nuclear facilities. Documentation and management measures should be in place for nuclear facilities to comply with existing QA/QC systems. 3.2 Decommissioning organization and manpower In general, decommissioning manpower and organization are important not only for safe decommissioning of nuclear facilities but also for estimate of the decommissioning cost, because labor cost due to the manpower and organization is the important fixed cost in the decommissioning of nuclear facilities. Therefore, the preliminary DP should describe a potential organization and estimated manpower to perform decommis sioning activities of the facility in the decommissioning phase [5, 6]. In addition, the facility licensee should describe a decommissioning support team in the operating orga nization including the main duties of its decommissioning workforce in the operation phase, which can prepare pre-decommissioning tasks during the operation period. And it is also required to describe the expertise required to perform the related service, and the qualification requirements and training requirements for maintaining its expertise in the preliminary DP. 3.3 Preliminary decommissioning cost estimate and finance assurance The decommissioning operator shall estimate the preliminary decommissioning cost considering the decommissioning strategy, facility/site characteristics, applied decommissioning technique, etc., which are determined at the design stage of the nuclear facilities and present the appropriateness of the estimated results [3]. The main factors affecting the preliminary cost are as follows. pp Characteristic data of nuclear facility/site and its decommissioning scenario. pp Experience/knowledge data of the decommissioning of the facility and overall decommissioning market environment (demand and supply). pp Decommissioning waste management: release criteria, availability of disposal facilities and acquisition of waste acceptance criteria. pp Schedule of spent fuel transfer campaign and availability of spent fuel transport/storage cask. pp Site release criteria and site reuse. pp Availability of manpower and decommissioning techniques. pp Asset recovery after decommissioning (asset valuation, asset recovery method, etc.). The assumptions and the strategic decisions for each of above factors should be clearly indicated in the preliminary DP, and they should be continuously managed so that they can be used to calculate the revised decommissioning cost for the amendment DP. The method of securing the decommissioning resources differs depending on the country. In Korea, based on its operating decommissioning cost funding system, the following items should be described in the preliminary DP. pp Disbursement fund accumulation according to result of decommissioning cost estimate every 2 years. pp The decommissioning cost items and the cost management plan is precisely specified. It is also necessary to conduct surveillance activities to maintain the security of decommissioning cost, such as the availability of the cost funding system, the suitability of the cost estimation, and the appropriateness of the cost utilization. For this, the decommissioning cost execution plan should be regularly checked step by step. 3.4 Site and environmental survey 3.4.1 Status of site and environment The site and environmental characteristic survey are conducted to obtain the construction permit and the operation license of the nuclear facility in the construction phase [5]. Therefore, using these characteristic data, the preliminary DP should describe the following site and environmental status data for the decommissioning of the facility, which is used as the basic input data of the decommis sioning environmental impact assessment and safety assessment. pp Meteorological and topographical characteristics to predict the spread of radioactive materials. pp Population data for environmental impact assessment. pp Provisions of equipment access to a decommissioning site and transportation of decommissioning waste. pp Assessing the social and economic impact due to the decommissioning business. The main items of site and environmental data to be used in the decommissioning of the nuclear facility will be selected from the site and environment reports prepared for the construction/operation license of the nuclear facility. The decommissioning operator needs to present the management plan for these important data related to the decommissioning it in the preliminary DP. 3.4.2 Radiological status of the facility, the site and the environment Radiological characteristic data are the basic inputs to all radiation safety assessment including radiation environmental impact assessment, worker exposure dose prediction. And it can also be used for the selection of the decommissioning tools/ method, the necessity of the shielding or iso lation facility, and the waste management policy [3]. DECOMMISSIONING AND WASTE MANAGEMENT 271 Decommissioning and Waste Management Guideline to Prepare a Preliminary Decommissioning Plan for Nuclear Facilities in Republic of Korea ı Byung-Sik Lee and Kyung-Woo Choi
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atw - International Journal for Nuclear Power | 05.2019

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