• Journal of Radiation Protection and Research
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• 제45권2호
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• pp.53-68
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• 2020

Background: International organizations such as the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) reported public exposure doses due to radionuclides released in the Fukushima nuclear accident a few years after the event. However, the reported doses were generally overestimated due to conservative assumptions such as a longer stay in deliberate areas designated for evacuation than the actual stay. After these reports had been published, more realistic dose values were reported by Japanese scientists. Materials and Methods: The present paper reviews those reports, including the most recently published articles; and summarizes estimated effective doses (external and internal) and issues related to their estimation. Results and Discussion: External dose estimation can be categorized as taking two approaches-estimation from ambient dose rate and peoples' behavior patterns-and measurements using personal dosimeters. The former approach was useful for estimating external doses in an early stage after the accident. The first 4-month doses were less than 2 mSv for most (94%) study subjects. Later on, individual doses came to be monitored by personal dosimeter measurements. On the basis of these measurements, the estimated median annual external dose was reported to be < 1 mSv in 2011 for 22 municipalities of Fukushima Prefecture. Internal dose estimation also can be categorized as taking two approaches: estimation from whole-body counting and estimation from monitoring of environmental samples such as radioactivity concentrations in food and drinking water. According to results by the former approach, committed effective dose due to ¹³⁴Cs and ¹³⁷Cs could be less than 0.1 mSv for most residents including those from evacuated areas. Conclusion: Realistic doses estimated by Japanese scientists indicated that the doses reported by WHO and UNSCEAR were generally overestimated. Average values for the first-year effective doses for residents in two affected areas (Namie Town and Iitate Village) were not likely to reach 10 mSv, the lower end of the doses estimated by WHO.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.133-140
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• 2016

Backgrounds: The accident at Fukushima Daiichi Nuclear Power Plant (NPP), March 2011, caused serious radioactive contamination over wide area in east Japan. Therefore, it is important to know the effect of the accident and the status of NPP. Materials and Methods: This paper provides a review on the status of radiation dose and radioactive contamination caused by the accident on the basis of publicized information. Results and Discussion: Monitoring of radiation dose and exposure dose of residents has been conducted extensively by the governments and various organizations. The effective dose of general residents due to the accident proved to be less than a mSv both for external and internal dose. The equivalent committed dose of thyroid was evaluated to be a few mSv in mean value and less than 50 mSv even for children. Monitoring of radioactivity concentration has been carried out on food ingredients, milk and tap water, and actual meal. These studies indicated the percentage of foods above the regulation standard was over 10% in 2011 but decreasing steadily with time. The internal dose due to foods proved to be tens of ${\mu}Sv$ and much less than that due to natural $^{40}K$ even in the Fukushima area and decreasing steadily, although high level concentration is still observed in wild plants, wild mushrooms, animals and some kind of fishes. Conclusion: According to extensive studies, not only the effect of the accident but also the pathway and countermeasures against radioactive contamination have been revealed, and they are applied very effectively for restoration of environment and reconstruction of the area.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.293-300
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• 2022

During the decommissioning of the nuclear facilities, the radioactive gases in pressure vessels may leak due to the demolition operations. The decommissioning site has large space, slow air circulation, and many large nuclear facilities, which increase the difficulty of workers' inhalation exposure assessment. In order to dynamically evaluate the activity distribution of radionuclides and the committed effective dose from inhalation in nuclear decommissioning environment, an inhalation exposure assessment method based on the modified eddy-diffusion model and the inhaled dose conversion factor is proposed in this paper. The method takes into account the influence of building, facilities, exhaust ducts, etc. on the distribution of radioactive gases, and can evaluate the influence of radioactive gases diffusion on workers during the decommissioning of nuclear facilities.

• Nuclear Engineering and Technology
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• 제32권4호
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• pp.350-360
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• 2000

In Korea, the dose limits are reduced and are set at the ICRP-60 iimits. However, derived limits tabulated as MPC in air and water are still specified in Notice No.98-12. There are some discrepancies between the primary dose limits and MPCs in air and water. Therefore, in order to accept ICRP-60 recommendations fully, derived limits such as ALI, DAC, ECL for radiological protection against ionizing radiation based on ICRP-60 recommendations were calculated using modified methods of those of 10 CFR part 20, dose limits and committed effective dose coefficients of the Basic Safety Standards of the IAEA. The derived limits in this study were also compared with those prescribed in 10 CFR part 20 as well as MPCs of Notice No. 98-12 in order to analyze the impact of implementing derived limits on nuclear facilities. ECLs in air and water for the control of radioactive discharge into the environment in this study are shown to have lower values (i.e. more conservative), for most part, than those in Notice No. 98-12. Especially, for uranium elements, ECLs in water are approximately a magnitude in the order of two lower than those in Notice No.98-12.

• Nuclear Engineering and Technology
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• 제42권1호
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• pp.109-114
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• 2010

Bioassay data analysis software (BiDAS-2007) has been developed by KAERI, which adds several new functions to its previous version. New functions of the BiDAS-2007 computer code enable the user not only to do a simultaneous analysis by using two or more types of bioassay for the best internal dose evaluation, but also to do a continual internal dose evaluation from a change of the internal exposure conditions such as an intake type (acute, chronic), an intake pathway (inhalation, ingestion), an absorption type (Type F, M, S), and a particle size (AMAD, activity median aerodynamic diameter), and also to estimate the intakes in various conditions of an internal exposure at a time. The values calculated by the BiDAS-2007 code are consistent and in good agreement with those values by IMIE-2004 code by Berkovski and IMBA code by Birchall. The BiDAS-2007 computer code is very useful and user-friendly to estimate the radionuclide intakes and committed effective doses of a radiation worker.

• Journal of Radiation Protection and Research
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• 제28권4호
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• pp.321-325
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• 2003

방사선작업종사자가 우라늄을 5년간 만성 흡입섭취하는 경우, 우라늄의 입자크기$(0.1{\sim}10{\mu}m)$, 흡수형태(Type M, Type S) 및 섭취형태(급성, 만성)가 방사선작업종사자의 내부피폭선량 평가 결과에 미치는 영향을 분석하였다. 우라늄을 1 Bq/day의 섭취율로 섭취할 경우 매분기 폐 방사능 값을 계산하여 실제 일상감시에서의 폐 방사능 측정값으로 간주하였고, 이 측정값으로부터 섭취량 및 예탁유효선량을 평가하였다. 5년간의 우라늄 섭취로 인한 예탁유효선량 평가 결과는 입자크기에 따라 $-37.0{\sim}49.8%$, 흡수형태에 따라 $15.9{\sim}56.6%$, 섭취형태에 따라 $0.55{\sim}4.52%$의 오차를 보였다. 이와 같이 입자크기 및 흡수형태는 분기별 측정값에 근거한 예탁유효선량 평가 결과에 큰 영향을 주었으나, 섭취형태는 평가 결과에 거의 영향을 주지 않는 것으로 나타났다.

• 방사성폐기물학회지
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• 제18권1호
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• pp.103-111
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• 2020

콘크리트 구조물 절단에 사용되고 있는 다이아몬드 와이어 쏘가 장착된 당김형 절단 장치의 단점을 개선하여 밀기형 절단장치를 개발하였다. 개발된 밀기형 절단장치에는 먼지 집진 커버가 부착되며 마찰열을 냉각하기 위한 건식이나 습식방법을 선택할 수 있다. 개발된 절단장치의 동작특성과 집진 먼지의 누설률 측정을 실험하였다. 시험결과 원활한 동작특성을 보였으며, 먼지의 누설률은 1.7%인 것으로 나타났다. 개발된 절단장비를 사용하여 생물학적 차폐 콘크리트 절단 시 작업자의 내부 피폭선량을 평가하였다. 보수적 평가를 위해 노심 중심부분을 절단하는 경우를 가정하였다. 비방사능이 99.5 Bq·g^-1인 누설 먼지로 인해 반면마스크를 착용한 작업자의 예탁유효선량은 0.25 mSv로 평가되었다. 개발된 밀기형 절단장비 사용 시 미량의 먼지 누설률로 인해 작업자의 방사선 피폭이 저감되며, 사용의 편리성으로 세부 절단 계획을 수립할 수 있어 방사성 콘크리트 폐기물 감량에도 기여할 수 있다. 따라서 원전의 방사화된 생물학적 차폐 콘크리트를 비롯하여 철근 콘크리트 구조물 해체 작업 시 절단 장비로서 사용될 수 있을 것이다.

• Journal of Radiation Protection and Research
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• 제28권1호
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• pp.43-50
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• 2003

본 연구는 호흡을 통해 우라늄을 만성 또는 급성섭취한 경우 생물분석 결과의 해석을 통해 예탁유효선량을 평가하는 실질적인 방법을 기술하고 있다. 인체에서의 우라늄 거동의 해석을 위해 인체의 장기를 ICRP에서 권고하는 소화기 모델, 호흡기 모델 그리고 생체역동학적 모델에 따라 일련의 수학적 격실로 구성하였다. Birchall의 알고리듬을 이용하여 각 격실에서의 균형방정식의 해석적인 해를 얻었으며 우라늄의 소변 배설함수와 폐 잔류함수를 획득하였다. 소변 중 우라늄 농도와 폐 계수기로 측정된 폐 부하량에 각각 배설 및 잔류함수를 적용하여 섭취모드에 따른 초기 섭취량 또는 총 섭취량을 계산하였다. 예탁유효선량은 ICRP 78에서 제공하는 선량 환산계수를 계산된 섭취량에 적용함으로써 평가된다.

• Journal of Radiation Protection and Research
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• 제38권3호
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• pp.138-142
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• 2013

본 연구는 부산 및 대전에 거주하는 일반인을 대상으로 소변 중 우라늄 농도를 분석하고 선량을 평가하였다. 그 결과 부산지역 거주자들의 소변 중 총 우라늄 농도는 0.556 - 1.53 $mBq\;L^{-1}$, 대전지역 거주자들은 2.18-4.55 $mBq\;L^{-1}$으로 부산지역 거주자들에 비해서 다소 높은 경향을 나타내었다. 이러한 경향은 대전지역이 지질학적으로 우라늄 함량이 높은 중생대 쥬라기 화강암류를 기반암으로 보고되고 있으며, 이는 거주지의 우라늄 농도와 거주자의 소변 중 우라늄 농도 간에 밀접한 관계가 있을 것으로 추정된다. 한편 본 연구에서는 소변 중의 우라늄 농도와 성별 및 연령과는 어떠한 상관성을 확인 할 수 없었다. 우라늄 섭취로 인한 유효선량은 부산지역 거주자의 경우 연간 0.472-1.41 ${\mu}Sv$, 대전지역 거주자의 경우 연간 1.99-4.15 ${\mu}Sv$ 정도인 것으로 평가되었다.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.960-966
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• 2021

A technical approach to design and carry out an experiment to determine the uptake of selected radionuclides in site-specific conditions in Kuwait was developed and successfully executed for developing a radioecological decision support system. The radionuclides from soil-to-plant transfer factors have been obtained for leafy and non-leafy vegetables, and root crops cultivated in Kuwait. Two types of vegetated soils were selected and spiked with high concentrations of three relatively short-lived selected radionuclides (⁸⁵Sr, ¹³⁴Cs, and ¹³³Ba). The highest strontium and barium transfer factors were found in the order: leafy vegetables > root crops > non-leafy vegetables. The approximate range of radiocesium transfer factor was found to be low in all plant groups and was comparable to those reported elsewhere in different soil types of temperate and tropical environments. A strong negative correlation between the obtained transfer factors and the distribution coefficient of the radionuclide in soil was found. It is recommended to adopt the newly derived parameters for the sensitive areas in Kuwait and other Gulf countries instead of using the generic parameters, whenever dose calculation codes are used. This will help to more accurately assess and predict the end results of the committed effective dose equivalent through ingestion pathway.