고리1호기 해체시 발생할 방사성금속폐기물 관리 옵션 연구

David S. Kessel,Chang-Lak Kim 한국방사성폐기물학회 2017 방사성폐기물학회지 Vol.15 No.2

방사성금속폐기물의 관리 옵션들을 안전성, 경제성, 작업자 피폭, 부피 감용 등의 선별 기준을 적용하여 비교 평가하였다. 원전 해체로부터 발생하는 금속폐기물의 관리 옵션에는 무구속 방출, 제한적 재사용, 그리고 직접 처분이 있다. 고려된 각 각의 옵션들은 금속폐기물의 절단과 용융에 의한 부피감용을 수반한다. AHP기법을 적용하여 각 옵션들의 순위를 부여하였 다. 방사성금속폐기물을 용융하여 금속 잉곳을 제조한 후 제한적 재이용 또는 무구속 방출하는 방안이 가장 효율적인 옵션 으로 도출되었다. The purpose of this paper is to evaluate several leading options for the management of radioactive metallic waste against a set of general criteria including safety, cost effectiveness, radiological dose to workers and volume reduction. Several options for managing metallic waste generated from decommissioning are evaluated in this paper. These options include free release, controlled reuse, and direct disposal of radioactive metallic waste. Each of these options may involve treatment of the metal waste for volume reduction by physical cutting or melting. A multi-criteria decision analysis was performed using the Analytic Hierarchy Process (AHP) to rank the options. Melting radioactive metallic waste to produce metal ingots with controlled reuse or free release is found to be the most effective option.

U.S. Policy and Current Practices for Blending Low-Level Radioactive Waste for Disposal

David S. Kessel,Chang-Lak Kim 한국방사성폐기물학회 2016 방사성폐기물학회지 Vol.14 No.3

우리나라를 포함한 많은 국가들에서 향후 원전 해체로 저준위폐기물이 대량으로 발생할 전망이다. 본 논문에서는 미국의저준위방사성폐기물 처분 관련 규제 기준을 분석하고, 특히 원자력발전소의 운영 및 해체를 포함하는 전주기에서 발생하는 폐기물의 처분 옵션을 확장하는 방안으로 사용되고 있는 저준위방사성폐기물의 블랜딩에 대해 검토하였다. 2007년 미국 NRC는 미국 저준위폐기물 관리 프로그램에 대한 전략분석 결과, 방사선위험도와 성능평가에 기반한 새로운 저준위폐기물 관리 규제의 필요성을 제기하였는데, 특히 방사성핵종 농도가 다른 폐기물의 블랜딩을 처분에 대한 옵션을 다양화할 수있는 안전한 방안으로 제시하였다. NRC는 블랜딩을 처분에 적합하도록 방사성핵종의 농도가 다른 저준위폐기물을 비교적균일하게 혼합(mixing)하는 것으로 정의하였다. 2015년 2월 농도 평균과 포장에 대한 NRC BTP의 개정판으로 공표된 블랜딩에 대한 구체적인 기술요건을 분석하였고 국내 해체폐기물에 대한 적용 방안도 예시하였다. 대량으로 발생할 해체폐기물에 대해 블랜딩과 농도평균을 적용하면 처분 효율성을 향상시킬 수 있다. 바이오쉴드 콘크리트에 대한 농도평균 적용에 대해 예시하였다. In the near future, many countries, including the Republic of Korea, will face a significant increase in low level radioactive waste (LLW) from nuclear power plant decommissioning. The purpose of this paper is to look at blending as a method for enhancing disposal options for low-level radioactive waste from the decommissioning of nuclear reactors. The 2007 U.S. Nuclear Regulatory Commission strategic assessment of the status of the U.S. LLW program identified the need to move to a risk-informed and performance-based regulatory approach for managing LLW. The strategic assessment identified blending waste of varying radionuclide concentrations as a potential means of enhancing options for LLW disposal. The NRC’s position is that concentration averaging or blending can be performed in a way that does not diminish the overall safety of LLW disposal. The revised regulatory requirements for blending LLW are presented in the revised NRC Branch Technical Position for Concentration Averaging and Encapsulation (CA BTP 2015). The changes to the CA BTP that are the most significant for NPP operation, maintenance and decommissioning are reviewed in this paper and a potential application is identified for decommissioning waste in Korea. By far the largest volume of LLW from NPPs will come from decommissioning rather than operation. The large volumes in decommissioning present an opportunity for significant gains in disposal efficiency from blending and concentration averaging. The application of concentration averaging waste from a reactor bio-shield is also presented.

Management of Spent Ion-Exchange Resins From Nuclear Power Plant by Blending Method

Nursaidatul Syafadillah Kamaruzaman,David S. Kessel,Chang-Lak Kim 한국방사성폐기물학회 2018 방사성폐기물학회지 Vol.16 No.1

With the significant increase in spent ion-exchange resin generation, to meet the requirements of Waste Acceptance Criteria (WAC) of the Wolsong disposal facility in Korea, blending is considered as a method for enhancing disposal options for intermediate level waste from nuclear reactors. A mass balance formula approach was used to enable blending process with an appropriate mixing ratio. As a result, it is estimated around 44.3% of high activity spent resins can be blended with the overall volume of low activity spent resins at a 1:7.18 conservative blending ratio. In contrast, the reduction of high activity spent resins is considered a positive solution in reducing the amount of spent resins stored. In an economic study, the blending process has been proven to lower the disposal cost by 10% compared to current APR1400 treatment. Prior to commencing use of this blending method in Korea, coordinated discussion, and safety and health assessment should be undertaken to investigate the feasibility of fitting this blending method to national policy as a means of waste predisposal processing and management in the future.

Management of Spent Ion-Exchange Resins From Nuclear Power Plant by Blending Method

Kamaruzaman, Nursaidatul Syafadillah,Kessel, David S.,Kim, Chang-Lak Korean Radioactive Waste Society 2018 방사성폐기물학회지 Vol.16 No.1

With the significant increase in spent ion-exchange resin generation, to meet the requirements of Waste Acceptance Criteria (WAC) of the Wolsong disposal facility in Korea, blending is considered as a method for enhancing disposal options for intermediate level waste from nuclear reactors. A mass balance formula approach was used to enable blending process with an appropriate mixing ratio. As a result, it is estimated around 44.3% of high activity spent resins can be blended with the overall volume of low activity spent resins at a 1:7.18 conservative blending ratio. In contrast, the reduction of high activity spent resins is considered a positive solution in reducing the amount of spent resins stored. In an economic study, the blending process has been proven to lower the disposal cost by 10% compared to current APR1400 treatment. Prior to commencing use of this blending method in Korea, coordinated discussion, and safety and health assessment should be undertaken to investigate the feasibility of fitting this blending method to national policy as a means of waste predisposal processing and management in the future.

Logistical Simulation for On-site Concrete Waste Management in Decommissioning

Lee, Eui-Taek,Kessel, David S.,Kim, Chang-Lak Korean Radioactive Waste Society 2019 방사성폐기물학회지 Vol.17 No.4

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.

Proposal for the management strategy of metallic waste from the decommissioning of Kori Unit 1 by using melting and segmentation technology

Seo, Hyung-Woo,Lee, Dong-Hee,Kessel, David S.,Kim, Chang-Lak Elsevier 2017 Annals of nuclear energy Vol.110 No.-

<P><B>Abstract</B></P> <P>The oldest commercial reactor in South Korea, Kori Unit 1 Nuclear Power Plant (NPP), will be permanently shut down starting in 2017. Since decommissioning of NPPs will generate a huge amount of radioactive metallic waste, proper treatment for decommissioning wastes is one of the key factors to decommission a plant successfully. Many studies have been conducted and experience accumulated for waste minimization and the reduction of disposal volume. Melting technology is one of the proven technologies for effectively managing the metallic waste and has been adopted by many countries. However, a licensed melting facility to dispose of metallic wastes from the NPP decommissioning has not been implemented in Korea.</P> <P>The purpose of this study is to establish a management plan for metallic waste and to evaluate the preliminary doses according to the acceptance criteria and operations at the facility. Based on the available research papers and empirical data from domestic and international experience, the operational concept and the melting technology principle were established and its dose and volume reduction effects were evaluated. The concept of operating a melting plant is to finally free release the ingots after melting or free release after a planned storage period. Based on this concept, the radioactive concentration of the scrap metal which can be treated was derived, demonstrating that melting can be applied to low level and very low level wastes above the clearance level. The RESRAD-RECYCLE computer code was used to assess worker doses and was rated within the regulatory limits in most scenarios, except for slag workers. Factors affecting the dose, such as methods of radiation protection, operating method and working time, will be important factors in establishing the melting facility and the radiological limits should also be determined accordingly.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The management strategy of the metallic waste from the decommissioning of Kori Unit 1 is proposed. </LI> <LI> The operational concept and the melting technology principle were established. </LI> <LI> Dose calculation was done and the highest dose was observed in the slag worker. </LI> </UL> </P>

Application of a Logistical Simulation Model to Planning of Soil Washing Process

Jihan Jeon,Jaeyeon Jung,Eutteum Oh,David S. Kessel,Changlak Kim 한국방사성폐기물학회 2018 한국방사성폐기물학회 학술논문요약집 Vol.2018 No.10