• Title/Summary/Keyword: Nuclear waste repository

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Swelling Pressures of a Potential Buffer Material for High-Level Waste Repository

  • Lee, Jae-Owan;Cho, Won-Jin;Chun, Kwan-Sik
    • Nuclear Engineering and Technology
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    • v.31 no.2
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    • pp.139-150
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    • 1999
  • The swelling pressure of a potential buffer material was measured and the effect of dry density, bentonite content and initial water content on the swelling pressure was investigated to provide the information for the selection of buffer material in a high-level waste repository. Swelling tests were carried out according to Box-Behnken's experimental design. Measured swelling pressures were in the wide range of 0.7 Kg/$\textrm{cm}^2$ to 190.2 Kg/$\textrm{cm}^2$ under given experimental conditions. Based upon the experimental data, a 3-factor polynomial swelling model was suggested to analyze the effect of dry density, bentonite content and initial water content on the swelling pressure The swelling pressure increased with an increase in the dry density and bentonite content, while it decreased with increasing the initial water content and, beyond about 12 wt.% of the initial water content, levelled off to nearly constant value.

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Analysis of Functional Criteria for Buffer Material in a High-level Radioactive Waste Repository

  • W. J. Cho;Lee, J. O.;K. S. Chun;Park, Hyun-Soo
    • Nuclear Engineering and Technology
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    • v.31 no.1
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    • pp.116-132
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    • 1999
  • This study is intended to analyze the requirements of a buffer material that is one of the major components of the engineered barriers in a high-level radioactive waste repository. The characteristics of potential materials for the buffer in the repository were analyzed and a candidate material was selected. And, based on the current knowledge and the information from various sources, the requirements of a buffer material were evaluated. Finally its quantitative functional criteria on the generic viewpoint has been recommended to be supplied as a guideline for the development of the reference disposal concept and the related buffer material in Korea. The criteria are composed of seven major items, such as hydraulic conductivity, retardation capacity, swelling potential and swelling pressure, thermal conductivity, longevity, organic matter content, and mechanical properties.

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Assessment of Gas Generation in Underground Repository of Low-Level Waste (저준위 방사성폐기물 처분장에서의 기체 발생 평가)

  • Cho, Chan-Hee;Kim, Chang-Lak;Lee, Myung-Chan;Park, Heui-Joo
    • Nuclear Engineering and Technology
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    • v.28 no.1
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    • pp.79-92
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    • 1996
  • In a repository containing low-level waste, gas generation will occur principally by the coupled processes of metal corrosion and microbial degradation of cellulosic waste. This paper describes a mathematical model designed to address gas generation by these mechanisms and assesses the potential effects of gas generation on the performance of a radioactive waste repository. The metal corrosion model incorporates a three-stage process encompassing aerobic and anaerobic corrosion regimes ; the microbial degradation model simulates the activities of eight different microbial populations, which are maintained as functions both of pH and of the concentrations of particular chemical species. A prediction is made for gas concentrations and generation rates over an assessment period of ten thousand years in a radioactive waste repository. The results suggest that H$_2$will be the principal gas generated within the radioactive waste cavern.

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A Deterministic Safety Assessment of a Pyro-processed Waste Repository (A-KRS 처분 시스템 결정론적 안전성 평가)

  • Lee, Youn-Myoung;Jeong, Jongtae;Choi, Jongwon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.10 no.3
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    • pp.171-188
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    • 2012
  • A GoldSim template program for a safety assessment of a hybrid-typed repository system, called "A-KRS," in which two kinds of pyro-processed radioactive wastes, low-level metal wastes and ceramic high-level wastes that arise from the pyro-processing of PWR nuclear spent fuels are disposed of, has been developed. This program is ready both for a deterministic and probabilistic total system performance assessment which is able to evaluate nuclide release from the repository and farther transport into the geosphere and biosphere under various normal, disruptive natural and manmade events, and scenarios. The A-KRS has been deterministically assessed with 5 various normal and abnormal scenarios associated with nuclide release and transport in and around the repository. Dose exposure rates to the farming exposure group have been evaluated in accordance with all the scenarios and then compared among other.

A Probabilistic Safety Assessment of a Pyro-processed Waste Repository (A-KRS 처분 시스템 확률론적 안전성 평가)

  • Lee, Youn-Myoung;Jeong, Jongtae
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.10 no.4
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    • pp.263-272
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    • 2012
  • A GoldSim template program for a safety assessment of a hybrid-typed repository system, called A-KRS, in which two kinds of pyro-processed radioactive wastes, low-level metal wastes and ceramic high-level wastes that arise from the pyro-processing of PWR nuclear spent fuels are disposed of, has been developed. This program is ready both for a deterministic and probabilistic total system performance assessment which is able to evaluate nuclide release from the repository and farther transport into the geosphere and biosphere under various normal, disruptive natural and manmade events, and scenarios. The A-KRS has been probabilistically assessed with 9 selected input parameters, each of which has its own statistical distribution for a normal release and transport scenario associated with nuclide release and transport in and around the repository. Probabilistic dose exposure rates to the farming exposure group have been evaluated. A sensitivity of 9 selected parameters to the result has also been investigated to see which parameter is more sensitive and important to the exposure rates.

Geochemical Modeling of U Solubility in Groundwater Conditions (지하수에서의 우라늄 용해도에 대한 지화학적 모델링 연구)

  • Cho, Young-Hwan;Han, Kyung-Won;Suh, In-Suk
    • Nuclear Engineering and Technology
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    • v.22 no.1
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    • pp.29-35
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    • 1990
  • Uranium solubilities have been calculated for a range of conditions expected in a nuclear waste disposal repository. Variables taken into consideration include the pH and Eh range expected for deep groundeaters, the effect of the composition of groundwater. The model used in these calculations is based on the assumption of chemical equilibrium. Calculations show that the major variables influencing uranium solubility under the repository conditions are pH and Eh. The results of this study can be applied to an assessment of the nuclear waste disposal.

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