• Title/Summary/Keyword: Low-and intermediate-level radioactive waste

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Performance Assessment of Low- and Intermediate-Level Radioactive Waste Disposal Facility in Korea by Using Complementary Indicator: Case Study with Radionuclide Flux (보조지표를 활용한 중·저준위 처분시설 성능평가: 방사성 핵종 플럭스 사례연구)

  • Jung, Kang-Il;Jeong, Mi-Seon;Park, Jin Beak
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.13 no.1
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    • pp.73-86
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    • 2015
  • The use of complimentary indicators, other than radiation dose and risk, to assess the safety of radioactive waste disposal has been discussed in a number of publications for providing the reasonable assurance of disposal safety and convincing the public audience. In this study, the radionuclide flux was selected as performance indicator to appraise the performance of engineered barriers and natural barrier in the Wolsong low- and intermediate-level waste disposal facility. Radionuclide flux showing the retention capability by each compartment of the disposal system is independent of assumptions in biosphere model and exposure pathways. The scenario considered as the normal scenario of disposal facility has been divided into intact or degraded silo concrete conditions. In the intact silo concrete, the radionuclide flux has been assessed with respect to the radionuclide retardation performance of each engineered barrier. In the degraded silo concrete, the radionuclide flux has been explored based on the performance degradation of engineered barriers and the relative significance of natural barrier quantitatively. The results can be used to optimally design the near-surface disposal facility being planned as the second project phase. In the future, additional complimentary indicators will be employed for strengthening the safety case for improving the public acceptance of low- and intermediate-level waste disposal facility.

Gas Migration in Low- and Intermediate-Level Waste (LILW) Disposal Facility in Korea (중·저준위 방사성폐기물 처분시설 폐쇄후 기체이동)

  • Ha, Jaechul;Lee, Jeong-Hwan;Jung, Haeryong;Kim, Juyub;Kim, Juyoul
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.12 no.4
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    • pp.267-274
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    • 2014
  • The first Low- and Intermediate-Level Waste (LILW) disposal facility with 6 silos has been constructed in granite host rock saturated with groundwater in Korea. A two-dimensional numerical modeling on gas migration was carried out using TOUGH2 with EOS5 module in the disposal facility. Laboratory-scale experiments were also performed to measure the important properties of silo concrete related with gas migration. The gas entry pressure and relative gas permeability of the concrete was determined to be $0.97{\pm}0.15bar$ and $2.44{\times}10^{-17}m^2$, respectively. The results of the numerical modeling showed that hydrogen gas generated from radioactive wastes was dissolved in groundwater and migrated to biosphere as an aqueous phase. Only a small portion of hydrogen appeared as a gas phase after 1,000 years of gas generation. The results strongly suggested that hydrogen gas does not accumulate inside the disposal facility as a gas phase. Therefore, it is expected that there would be no harmful effects on the integrity of the silo concrete due to gas generation.

Development of Two-Dimensional Near-field Integrated Performance Assessment Model for Near-surface LILW Disposal (중·저준위 방사성폐기물 천층처분시설 근계영역의 2차원 통합성능평가 모델 개발)

  • Bang, Je Heon;Park, Joo-Wan;Jung, Kang Il
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.12 no.4
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    • pp.315-334
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    • 2014
  • Wolsong Low- and Intermediate-level radioactive waste (LILW) disposal center has two different types of disposal facilities and interacts with the neighboring Wolsong nuclear power plant. These situations impose a high level of complexity which requires in-depth understanding of phenomena in the safety assessment of the disposal facility. In this context, multidimensional radionuclide transport model and hydraulic performance assessment model should be developed to identify more realistic performance of the complex system and reduce unnecessary conservatism in the conventional performance assessment models developed for the $1^{st}$ stage underground disposal. In addition, the advanced performance assessment model is required to calculate many cases to treat uncertainties or study parameter importance. To fulfill the requirements, this study introduces the development of two-dimensional integrated near-field performance assessment model combining near-field hydraulic performance assessment model and radionuclide transport model for the $2^{nd}$ stage near-surface disposal. The hydraulic and radionuclide transport behaviors were evaluated by PORFLOW and GoldSim. GoldSim radionuclide transport model was verified through benchmark calculations with PORFLOW radionuclide transport model. GoldSim model was shown to be computationally efficient and provided the better understanding of the radionuclide transport behavior than conventional model.

Development and Application of SITES (부지환경종합관리시스템 개발과 적용)

  • Park, Joo-Wan;Yoon, Jeong-Hyoun;Kim, Chank-Lak;Cho, Sung-Il
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.6 no.3
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    • pp.205-215
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    • 2008
  • SITES(Site Information and Total Environmental Data Management System) has been developed for the purpose of systematically managing site characteristics and environmental data produced during the pre-operational, operational, and post-closure phases of a radioactive waste disposal facility. SITES is an integration system, which consists of 4 modules, to be available for maintenance of site characteristics data, for safety assessment, and for site/environment monitoring; site environmental data management module(SECURE), integrated safety assessment module(SAINT), site/environment monitoring module(SUDAL) and geological information module for geological data management(SITES-GIS). Each module has its database with the functions of browsing, storing, and reporting data and information. Data from SECURE and SUDAL are interconnected to be utilized as inputs to SAINT. SAINT has the functions that multi-user can access simultaneously via client-server system, and the safety assessment results can be managed with its embedded Quality Assurance feature. Comparison between assessment results and environmental monitoring data can be made and visualized in SUDAL and SITES-GIS. Also, SUDAL is designed that the periodic monitoring data and information could be opened to the public via internet homepage. SITES has applied to the Wolsong low- and intermediate-level radioactive waste disposal center in Korea, and is expected to enhance the function of site/environment monitoring in other nuclear-related facilities and also in industrial facilities handling hazardous materials.

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A Study on the Problems and Improvement of the Safety Management Law of Nuclear Facilities -Focused on Safety Management of Aquatic Products- (원자력시설 안전관리 법제의 문제점과 개선방안 연구 -수산물의 안전관리를 중심으로-)

  • Lee, Woo-Do
    • The Journal of Fisheries Business Administration
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    • v.50 no.2
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    • pp.23-40
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    • 2019
  • The main purpose of this study is to analyze and examine the problems of the law systems of the safety and maintenance of nuclear facilities and to propose the improvements with respect to the related problems especialy focused on safety management of aquatic products. Therefore, the results of the paper would be helpful to build an effective management law system of safety and maintenance of nuclear facilities and fisheries products. The research methods are longitudinal and horizontal studies. This study compares domestic policies with foreign policies of nuclear plants and aquatic products. Using the above methods, examining the current system of nuclear-related laws and regulations, we have found that there exist 13 Acts including "Nuclear Safety Act", etc. Safety laws related on nuclear facilities have seven Acts including "Nuclear Safety Act", "the Act on Physical Protection and Radiological Emergency", "Radioactive waste control Act", "Act on Protective Action Guidelines against Radiation in the Natural Environment", "Special Act on Assistance to the locations of facilities for disposal low and intermediate level radioactive waste", "Korea Institute of Nuclear Safety Act". "Act on Establishment and Operation of the Nuclear Safety and Security Commission". The seven laws are composed of 119 legislations. They have 112 lower statute of eight Presidential Decrees, six Primeministrial Decrees and Ministrial Decrees, 92 administrative rules (orders), 6 legislations of local self-government aself-governing body. The concluded proposals of this paper are as follows. Firstly, we propose that the relationship between the special law and general law should be re-established. Secondly, the terms with respect to law system of safety and maintenance of nuclear plants should be redefined and specified. Thirdly, it is advisable to re-examine and re-establish the Law System for Safety and Maintenance of Nuclear Facilities. and environmental rights like the French Nuclear Safety Legislation. Lastly, inadequate legislation on the aquatic pollution damage should be re-established. It is necessary to ensure sufficient transparency as well as environmental considerations in the policy decisions of the Korean government and legislation of the National Assembly. It is necessary to further study the possibilities of accepting the implications of the French legal system as a legal system in Korea. In conclusion, the safety management of nuclear facilities is not only focused on the secondary industry and the tertiary industry centering on power generation and supply, but also on the primary industry, which is the food of the people. It is necessary to prevent damage to be foreseen. Therefore, it is judged that there should be no harm to the people caused by contaminated marine products even if the "Food Safety Law for Prevention of Radiation Pollution Damage" is enacted.

Preliminary Post-closure Safety Assessment of Disposal Options for Disused Sealed Radioactive Source (폐밀봉선원 처분방식별 폐쇄후 예비안전성평가)

  • Lee, Seunghee;Kim, Juyoul;Kim, Sukhoon
    • Economic and Environmental Geology
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    • v.49 no.4
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    • pp.301-314
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    • 2016
  • Disused Sealed Radioactive Sources (DSRSs) are stored temporally in the centralized storage facility of Korea Radioactive Waste Agency (KORAD) and planned to be disposed in the low- and intermediate-level radioactive waste (LILW) disposal facility in Gyeongju city. In this study, preliminary post-closure safety assessment was performed for DSRSs in order to draw up an optimum disposal plan. Two types of disposal options were considered, i.e. engineered vault type disposal and rock cavern type disposal which were planned to be constructed and operated respectively in LILW disposal facility in Gyeongju city. Assessment end-point was individual effective dose of critical group and calculated by using GoldSim code. In normal scenario, the maximum dose was estimated to be approximately $1{\times}10^{-7}mSv/yr$ for both disposal options. It meant that both options had sufficient safety margin when compared with regulatory limit (0.1 mSv/yr). Otherwise, in well scenario, the maximum dose exceeded regulatory limit of 1 mSv/yr in engineered vault type disposal and the exposure dose was mainly contributed by $^{226}Ra$, $^{210}Pb$ (daughter nuclide of $^{226}Ra$) and $^{237}Np$ (daughter nuclide of $^{241}Am$). For rock cavern type disposal, even though the peak dose satisfied regulatory limit, the exposure doses by $^{14}C$ and $^{237}Np$ were relatively high above 10% of regulatory limit. Therefore, it is necessary to exclude $^{14}C$, $^{226}Ra$ and $^{241}Am$ for two type of disposal options and additional management such as long-term storage and development of disposal container for those radionuclides should be performed before permanent disposal for conservative safety and security.

Evaluation of Dark Spots Formated on the High Temperature Metal Filter Elements (고온 금속필터 element 표면에 생성된 반점에 대한 평가)

  • Park, Seung-Chul;Hwang, Tae-Won;Moon, Chan-Kook
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.6 no.3
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    • pp.171-178
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    • 2008
  • Metal filter elements were newly introduced to the high temperature filter(HTF) system in the low- and intermediate-level radioactive waste vitrification plant. In order to evaluate the performance of various metal materials as filter media, elements made of AISI 316L, AISI 904L, and Inconel 600 were included to the test set of filter elements. At the visual inspection to the elements performed after completion of each test, a few dark spots were observed on the surface of some elements. Especially they were found much more at the AISI 316L elements than others. To check the dark spots are the corrosion phenomena or not, two kinds of analyses were performed to the tested filter elements. Firstly, the surfaces or the cross sections of filter specimens cut out from both normal area and dark spot area of elements were analyzed by SEM/EDS. The results showed that the dark spots were not evidences of corrosion but the deposition of sodium, sulfur and silica compounds volatilized from waste or molten glass. Secondly, the ring tensile strength were analyzed for the ring-shape filter specimens cut out from each kind of element. The result obtained from the strength tested showed no evidence of corrosion as well. Conclusionally, depending on the two kinds of analysis, no evidences of corrosion were found at the tested metal filter elements. But the dark spots formed on the surface could reduce the effective filtering area and increase the overall pressure drop of HTF system. Thus, continuous heating inside filter housing up to dew point will be required normally. And a few long-period test should be followed for the exact evaluation of corrosion of the metal filter elements.

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