• Economic and Environmental Geology
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• v.29 no.2
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• pp.215-225
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• 1996

All the radionuclides in high-level nuclear waste will decay to harmless levels eventually but for some radionuclides decay is so slow that their radiation remains dangerous for times on the order of tens or hundreds of thousands of years. At the present time, the most favorite disposal plan for high-level radioactive waste is a mined geological disposal in which canister enclosing stable solid form of radioactive waste is placed in mined cavities locating hundred meters below the surface. The chief hazard in such disposal is dissolution of radionuclides from the waste in the groundwater that will eventually carry the dissolved radionuclides to surface environments. The hazard from possible escape of the radionuclides through groundwater can be delayed by engineered and geologic barriers. The engineered barriers can become useless by unexpected geologic catastrophe such as volcanism, earthquake, and tectonic movement and by fraudulent work such as careless construction, improperly welded canisters within the first few decades or centuries. As a result, dangerously radioactive waste which is still intensively radioactive is directly exposed to attack by moving groundwater. All the more, it is almost impossible to control repositories for times more than 10,000 years. Therefore, naturally controlled geologic, barriers whose properties will not be changed within 10,000 years are important to guarantee the safety of repositories of high-level radioactive waste. In Sweden and France, the suitability of granite for the mined geological disposal of high-level waste has been studied intensively. According to the research in Sweden and France, granites has the following physio-chemical characteristics which can delay the transportation of radionuclide by groundwater. First, the permeabilities of granites decreases as the depth increases and is $10^{-8}{\sim}10^{-12}m/s$ at depth below 300 m. Second, groundwater at depth below 300 m has pH=7-9 and reducing condition (Eh=-0.1~0.4). This geochemical condition is desirable to prevent both canister and solid waste from corrosion. Third most radionuclides are not transported by low solubilities and some radionuclide with high solubility such as Cs and Sr are retarded by absorption of geologic media through which ground water flows. Therefore, if high-level waste is disposed at depth below 300 m in the granite body which has a low permeability and is geologically stable more than 10,000 years, the safety of repositories from the hazard due to radionuclide escape can guaranteed for more than 10,000 years.

• The Journal of the Petrological Society of Korea
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• v.17 no.3
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• pp.179-190
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• 2008

The distribution characteristics of some major environmental radionuclides ($^{40}K$, $^{228}Ac$, $^{226}Ra$, $^{222}Rn$) and U in rocks, soils and soil gas were studied at Geumjeong-Gu, Busan, Korea. The activities of radionuclides in granitic rocks are decreased in the odor of $^{40}K$>thorium decay series>uranium decay series. This reveals that Th was relatively more enriched in granitic rocks than U. The U content and activity of $^{226}Ra$ and $^{228}Ac$, however, don't reflect the fractionation sequence of granitic rocks in the study area. The activities of all these radionuclides and U content in soils are generally higher than in rocks, and their distribution in rocks, soils and soil gas show very low co-relationship. These facts indicate that the activities of radionuclides in soil and soil gas were greatly affected by leaching and adsorption properties of the radionuclides and their parents during weathering and pedogenetic process rather than their concentrations in parent rocks.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.501-511
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• 2017

Natural radionuclides such as uranium and radon from 170 groundwater wells in Jeonnam Province were investigated, together with hydrogeochemical properties, and concentration maps of uranium and radon were also constructed in this study. Characteristics of their concentrations and occurrence were discussed using hydrogeochemical factors and geostatistical methods based on individual geological units. Though uranium and radon in groundwater show a wide range in the concentration, most of which occur as low levels except a few sites. Based on factor analysis, correlation coefficients between uranium and radon are very low. Such results verify that these radionuclides behave independently, well consistent with most previous results investigated nationwide in groundwater. Besides uranium and radon, most hydrochemical components in groundwater show a close relation to indicate the water-rock interaction taken place actively in aquifer.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.78-87
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• 1988

This article suggests the radionuclides which should be considered more important to the offsite consequence assesment during a nuclear power plant accident. For this purpose, the relative importance to the early health effects of released radionuclides on the major organs during the accident is estimated under the assumption of the same release fraction. The inventories of the 25 elements, 54 nuclides selected in the Reactor Safety Study are calculated by ORIGEN 2 code. The organs of interest in the estimation are G. I. track, bone marrow, thyroid and lung. The result shows the relative potential importance of radionuclides as follows: For G.I. track, Np, Ce, Ru, Y, and Zr are of importance in sequence, Np, I, La, Sr, Ba for bone marrow, I and Te for thyroid, Cm, Ce, Ru, Pu, Zr for lung. In addition to iodine and noble gases, therefore, the potential contribution of those nuclides listed above to the offsite consequences should not be overlooked for some accidents of particular sequence.

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.88-94
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• 2020

Background: The International Commission on Radiological Protection (ICRP) has recently published report series on the occupational intakes of radionuclides (OIR) for internal dosimetry of radiation workers. In this study, the optimized monitoring program including the monitoring interval and the minimum detectable activity (MDA) of major radionuclides was suggested to perform the routine individual monitoring of internal exposure based on the ICRP OIR. Materials and Methods: The derived recording levels and the critical monitoring quantities were reviewed from international standards or guidelines by the International Atomic Energy Agency (IAEA), the International Organization for Standardization (ISO), and the European Radiation Dosimetry Group (EURADOS). The OIR data viewer provided by ICRP was used to evaluate the monitoring intervals and the MDA, which are derived from the reference bioassay functions and the dose coefficients. Results and Discussion: The optimal monitoring intervals were determined taking account of two requirement conditions on the potential intake underestimation and the MDA values. The MDA requirement values of the selected radionuclides were calculated based on the committed effective dose from 0.1 mSv to 5 mSv. The optimized routine individual monitoring program was suggested including the optimal monitoring intervals and the MDA requirements. The optimal MDA values were evaluated based on the committed effective dose of 0.1 mSv. However, the MDA can be adjusted considering the practical operation of the routine individual monitoring program in the nuclear facilities. Conclusion: The monitoring intervals and the MDA as crucial factors for the routine monitoring were described to suggest the optimized routine individual monitoring program of the occupational intakes. Further study on the alpha/beta-emitting radionuclides as well as short lived gamma-emitting nuclides will be necessary in the future.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.485-495
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• 2005

This study was conducted to investigate sorption and desorption behaviors of radionuclides (Cobalt and Strontium) in natural soil. Sorption kinetics and isotherms were analyzed to predict sorption behaviors of radionuclides in natural soil and the experimental data were fitted to several sorption models. Desorption experiments were also performed with or without CMCD at constant pH and ion strength conditions. The results showed that $Sr^{2+}$ was more strongly sorbed than $Co^{2+}$ in natural soil. Both $Co^{2+}$ and $Sr^{2+}$ followed a pseudo-second order kinetics and Sips model. The desorption-resistance of $Co^{2+}$ and $Sr^{2+}$ was estimated using a natural surfactant Carboxymethyl-${\beta}$-cyclodextrin(CMCD) or non-desorbing fraction. Desorption of radionuclides was partially irreversible and $Sr^{2+}$ was more resistant than $Co^{2+}$ Addition of CMCD facilitated desorption of $Co^{2+}$ and $Sr^{2+}$ from soil.

• Nuclear Engineering and Technology
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• v.39 no.6
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• pp.747-752
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• 2007

The Proton Engineering Frontier Project (PEFP) has designed and developed a proton linear accelerator facility operating at 100 MeV - 20 mA. The radiological effects of such a nuclear facility on the environment are important in terms of radiation safety. This study estimated the production rates of radionuclides in the soil around the accelerator facility using MCNPX. The groundwater migration of the radioisotopes was also calculated using the Concentration Model. Several spallation reactions have occurred due to leaked neutrons, leading to the release of various radionuclides into the soil. The total activity of the induced radionuclides is approximately $2.98{\times}10^{-4}Bq/cm^3$ at the point of saturation. $^{45}Ca$ had the highest production rate with a specific activity of $1.78{\times}10^{-4}Bq/cm^3$ over the course of one year. $^3H$ and $^{22}Na$ are usually considered the most important radioisotopes at nuclear facilities. However, only a small amount of tritium was produced around this facility, as the energy of most neutrons is below the threshold of the predominant reactions for producing tritium: $^{16}O(n,\;X)^3H$ and $^{28}Si(n,X)^3H$ (approximately 20 MeV). The dose level of drinking water from $^{22}Na$ was $1.48{\times}10^{-5}$ pCi/ml/yr, which was less than the annual intake limit in the regulations.

• Journal of Soil and Groundwater Environment
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• v.14 no.5
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• pp.51-61
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• 2009

This study was performed to research the characteristic of radionuclides of 80 groundwater monitoring networks in Busan. According to the research, average concentration of Uranium was $4.33\;{\mu}g/L$, maximum concentration of Uranium was $171.55\;{\mu}g/L$ among the 80 sampling sites. One sample exceeded the Proposal standard of drinking water in USA in Uranium ($30\;{\mu}g/L$) and four samples exceeded the recommendatory value of WHO about Uranium ($15\;{\mu}g/L$). Radon and gross-$\alpha$ concentration of all samples were far less than the Proposal standard of drinking water in USA. In this study average concentration of radionuclides in underground water wasn't too high, but needed to control the concentration of them to prevent exposure to the people. And it needs to be taken measures in some sites with high concentration of Uranium by closing the pipe line or etc through more studies.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.115-121
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• 1998

Adsorption characteristics of the radionuclides and stable elements on AMP and $MnO_2$ in the seawater have been investigated. The adsorption yield of AMP was 97.5% for $^{137}Cs$, 11.8% for $^{85}Sr$, and 15.1% for $^{131}I$, while being less than 6% for other radionuclides and elements. The AMP showed the highest adsorption yield for $^{137}Cs$. The adsorption yields of $MnO_2$ were more than 90% for all radionuclides and elements, except for $^{40}K$, $^{137}Cs$ and $^{203}Hg$ of which the adsorption yields were less than 8%.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.235-243
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• 2019

Radioactive materials are released into the air and deposited on the surface soil after a nuclear accident. Radionuclides deposited in soil are transported by precipitation to nearby environments and contaminate the surface water system. Basic data on surface watershed and soil erosion models have been collected and analyzed to evaluate the behavior of radionuclides deposited on surface soil after a nuclear accident. Data acquisition and analysis in aquatic environment were performed to investigate the physical characteristics and variation of biota in rivers and lakes of the Nakdong river area near the Wolsong nuclear power plant. For these purposes, a digital map, and hydrological, water quality and biota data were gathered and a systematic database (DB) was constructed in connection with them. Constructed aquatic DB will be supplied and used in surface watershed and soil erosion models for investigation of long-term movement of radionuclides in adsorptive form in surface soil. Finally, basic data and established models will be utilized for general radiological impact assessment in aquatic environment.