• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.95-100
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• 1996

현재 방사선 비상훈련에 사용하는 TID-14844 의 방사선원항은 너무 보수적이고, 각 사고경로별로 방사선원항의 특성을 나타낼 수 없으므로, 원전의 비상사고 발생시 주민의 피폭선량을 최소화하기 위한 발전소 요원의 신속, 정확한 대처능력을 배양하기 위하여 현실적인 방사선원항 평가자료의 필요성이 대두되어 왔다. 본 연구에서는 보수성을 배제한 최적 분석기법을 이용하여 선정된 사고경로에 대해 MAAP 전산코드로 사고진행 및 방사선원항을 분석하였고, 격납건물내 방사선계측기의 예측치를 평가할 수 있는 방법론을 개발하였으며, 이를 통해 사고경로별 안전변수 및 방사선 계측기 등에서의 사고 진행에 따른 예측치 등을 계산함으로써 효과적인 비상대책 수립을 위한 실질적인 방사선원항 데이타 베이스를 구축하였다.

• Journal of Radiation Protection and Research
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• v.9 no.1
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• pp.26-32
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• 1984

The exposure doses by the radioactive gaseous effluents from nuclear power plants are investigated in the two cases of normal operation and hypothetical accident. Gaussian equation is adapted in the normal operation as the diffusion model of effluents for long period, which uses annual average meteorological data. But the real time models have been used in the case of accidents which analyze the changes of wind direction and speed. In this study the annual exposure doses by the normal operation of Kori unit 1 during $1977{\sim}1982$ were calculated on the basis of the atmospheric diffusion factor by the Gaussian straight line model. And the image processing technique was suggested as the effective method through the wind tunnel experiments to get the characteristic value of atmospheric diffusion coefficient required especially in the accidents of nuclear power plants.

• Journal of Radiation Protection and Research
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• v.23 no.4
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• pp.251-257
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• 1998

A diffusion model of radioactive gaseous effluents is improved to apply for domestic nuclear power plants. Up to now, XOQDOQ computer code package developed by U. S NRC has been used for the assessment of radioactive plume dispersion by normal operation of domestic nuclear power plants. XOQDOQ adopts the straight-line Gaussian plume model which was basically derived for the plane terrain. However, since there are so many mountains in Korea, the several shortcomings of XOQDOQ are improved to consider the complex terrain effects. In this work, wind direction change is considered by modifying the wind rose frequency using meteorological data of the local weather stations. In addition, an effective height correction model, a plume reduction model due to plume penetration into mountain, and a wet deposition model are adopted for more realistic assessments. The proposed methodology is implemented in Yongkwang nuclear power plants, and can be used for other domestic nuclear power plants.

• Journal of Radiation Protection and Research
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• v.25 no.2
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• pp.75-80
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• 2000

The predicted results of INDAC code were compared with measured $^3H$ concentrations in air and pine-needle around the Wolsung site. The optimal sets of input data to INDAC were in addition selected by comparing the measured values with the predicted values of INDAC based on various conditions such as the release modes of effluents into the environment, the classification of wind classes, and the consideration of terrain. The predicted $^3H$ concentrations in air and pine-needle were shown to have good agreement with measured values, although there are some limitations such as uncertainties in measured values, complex topology around the site, and the land-sea breeze effects. The assumption on the $^3H$ behavior in vegetables or plants that the ratio of $^3H$ concentration in plant water to $^3H$ concentration in atmospheric water is 1/2 was shown to be conservative in terms of the audit calculation performed by the regulator. It was also found that data sets based on mixed mode and no terrain data were not appropriate for the audit calculation ensuring the compliance with regulations. Thus, if the mixed mode is considered as the release mode of effluents into the environment, meteorological data measured at 58 m height and terrain data should be used to evaluate the atmospheric dispersion factor.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.857-862
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• 2020

In March 2011, a tsunami off Japan caused radioactive material that had seeped into the sea from the Fukushima nuclear accident to flow to the Pacific Ocean, causing pollution to sea life. For a comparative evaluation with the area surrounding the site of a nuclear power plant by the release of radioactive materials, an area 20 to 30 km away from the emergency protection plan area was selected as a comparative point considering weather conditions, population distribution, etc. In addition, the government intends to analyze the minimum detection radiation received by residents around the nuclear power plant and evaluate the effective dose. Analysis of tritium radiation from water samples showed that most of the samples were not detected and that 0.0014 % to 0.777 % of the annual legal standard of 1 mSv for the general public had little effect on the human body. Therefore, the measurement and analysis of water samples around the nuclear power plant site is expected to help relieve anxiety, such as exposure to the general public and neighboring residents due to radiation release.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.165-174
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• 1993

For the safety assessment of the demonstration-scale incineration plant for treating the combustible radioactive wastes, radiation doses of a worker and a residential individual were estimated. The demonstration plant showed a good performance of trial-burn tests using non-radioactive tracers with resulting In high mass reduction of around 40 times and very low emmission of dusts through a stack, which promised a high decontamination factor in an order of 10$^{7}$ . Based on the result s obtained from the trial-burns in the process, the estimation of radiation dose for workers and general publics near the plant was made using dose pathway calculation theories. The parametric values for calculation were selected from design and operational results of the process and from more conservative conditions In reference data. The estimated annual doses for workers and residential indivisuals were 3.07 $\times$ 10$^{-4}$ and 4.35 X 10$^{-8}$ $\mu$Sv/y, respectively, which were high enough to operate the process when comparing with the allowable dose limit in the regulation. The dose calculation models were quite applicable with showing an excellent safety for the process.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.299-311
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• 2019

Decommissioning is a critical issue in Korea. Although compared with the operation of nuclear power plants the release of radioactive materials during decommissioning is not expected to be significant, residents should always be protected from radiation exposure. To manage this effectively, Annual Release Objectives (ARO) and Annual Release Limits (ARL) were derived from dose standards in the NSSC Notice and dose limit for the public. Based on meteorological data for the three years from 2008 to 2010 in the Shin Kori nuclear power plant site, atmospheric dispersion and ground deposition factors of gaseous effluent were evaluated using the XOQDOQ computer code. The exposure dose was evaluated using the ENDOS-G computer code. Because of differences in radiological sensitivity according to age groups, the results of Annual Release Objectives (ARO) and Annual Release Limits (ARL) showed significant differences depending on the radionuclides. The evaluation methodology of this study will provide meaningful information for radioactive effluent management for decommissioning of nuclear power plants.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.1
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• pp.107-122
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• 2018

Kori unit 1, the oldest commercial nuclear power plant in South Korea, was permanently shut down in June 2017. There are a lot of things to consider in decommissioning nuclear power plants, and one of them is the radiological environmental impact assessment. Performed to promote the health and safety of residents around the nuclear power plant, radiological environmental impact assessment aims to confirm that off-site radiological dose from radioactive material released from the facility does not exceed the regulatory criteria. There are three main parts of environmental impact assessment: pre-decommissioning environmental monitoring, environmental monitoring during decommissioning, and impact on nearby residents. At present, although the Korea Nuclear Safety Act stipulates that radiological environmental impact assessment resulting from decommissioning should be carried out, the details have not been specified. Therefore, this paper compares and analyzes guidelines for evaluation of radiological environmental impacts of nuclear power plants overseas, and presents a draft on the assessment of radiological dose resulting from decommissioning according to the Korean situation.

• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.50-63
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• 1985

A derivation of new release limit, named Derived Release Limit(DRL), into the atomsphere from a reference nuclear power plant has been performed on the basis of the new system of dose limitation recommended by the ICRP, instead of the (MPC)a limit which has been currently used until now as a general standard for radioactive effluents in Korea. In DRL Calculation, a Concentration Factor Method was applied, in which the concentrations of long-term routinely released radionuclides were in equilibrium with dose in environment under the steady state condition. The analytical model used in the exposure pathway analysis was the one which has been suggested by the USNRC and the exposure limits applied in this analysis were those recommended by the USEPA lately. In the exposure pathway analysis, all of the pathways are not considered and some may be excluded either because they are not applicable or their contribution to the exposure is insignificant compared with other pathways. In case, the environmental model developed in this study was applied to the Kori nuclear power plant as the reference power plant, the highest DRL value was calculated to be as $9.10{\times}10^6Ci/yr$ for Kr-85 in external whole body exposure from the semi-infinite radioactive cloud, while the lowest DRL value was observed 3.64Ci/yr for Co-60 in external whole body exposure from the contaminated ground, by the radioactive particulates. The most critical exposure pathway to an individual in the unrestricted area of interest (Kilchun-Ri, 1.3 km to the north of the release point) seems to be the exposure pathway from the contaminated ground and the most critical radionuclide in all pathways appears to be Co-60 in the same pathway. When comparing the actual release rate from KNU-l in 1982 with the DRL's obtained here the release of radionuclides from KNU-1 were much lower than the DRL's and it could be conclued that the exposure to an individual had been kept below the exposure limits recommended by the USEPA.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.553-558
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• 2000

Since 1977, KAERI has conducted the fundamental R&D on the permanent disposal of potential HLW repository in Korea. The first ten year project is divided into three short-term phase studies. The first phase study which shall be finished in March of 2000, has the prime target to develop the disposal concept of HLW. Throughout this study the preliminary and generic disposal repository system has been introduced. The potential repository is proposed to be emplaced into crystalline rocks which is the most common rock types in Korea. The proposed depth of the repository is between 300 to 700 meter. The numerical code, MASCOT-K was developed to asserts the long term safety of the proposed repository concept. Based on this conceptual design preliminary safely assessment was performed. Results show that for the given disposal system the potential radioactive release it well below the regulatory limit.