• Nuclear Engineering and Technology
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• 제51권1호
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• pp.325-336
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• 2019

The activity concentrations of $^{226}Ra$, $^{232}Th$, and $^{40}K$ from 102 building materials samples were determined using a high-purity germanium (HPGe) detector. The activity concentrations were evaluated for possible radiological hazards to the human health. The excess lifetime cancer risks (ELCR) were also estimated, and the average values were recorded as $0.42{\pm}0.24{\times}10^{-3}$, $3.22{\pm}1.83{\times}10^{-3}$, and $3.65{\pm}1.85{\times}10^{-3}$ for outdoor, indoor, and total ELCR respectively. The activity concentrations were further subjected to RESRAD-BUILD computer code to evaluate the long-term radiation exposure to a dweller. The indoor doses were assessed from zero up to 70 years. The simulation results were $92{\pm}59$, $689{\pm}566$, and $782{\pm}569{\mu}Sv\;y^{-1}$ for indoor external, internal, and total effective dose equivalent (TEDE) respectively. The results reported were all below the recommended maximum values. Therefore, the radiological hazards attributed to building materials under study are negligible.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2010년도 춘계학술대회
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• pp.231-237
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• 2010

The purpose of this study was to investigate the actual conditions of radiation safety supervision in animal clinics using quality assurance (QA) and quality control (QC) of diagnostic X-ray units. The surveys for QA/QC, equipment condition, and safety supervision were carried out in 18 animal clinics randomly. The QA/QC included reproducibility of dose exposure, kVp, mAs, collimator accuracy test, collimator luminance test, X-ray view box luminance test, grounding system equipment test and external leakage current test. As a result, 44.44% of reproducibility of dose exposure was proper, 81. 25% of kVp test was good, and 100% of mAs test was appropriate. Also, 66.66% of collimator accuracy test was proper, 61.11% of collimator luminance test was good, 53.13% of X-ray view box luminance test was suitable. In addition, only 5.55% of grounding system equipment and ground resistance was proper, 63.64% of external leakage current test was appropriate in grounding system equipment test.

• 디지털콘텐츠학회 논문지
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• 제13권2호
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• pp.151-157
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• 2012

방사선 구역 내부의 공간선량은 의학의 발전과 더불어 방호시설이 잘 되어 있어도 작업종사자의 피폭을 증가시킬 우려가 있다. 핵의학과 내의 분배실은 항상 공간선량이 존재하므로 작업종사자의 피폭선량을 예측하기 위하여 분배실 내부의 공간선량을 측정, 분석 하였다. 핵의학과 $^{18}F$ 분배실의 공간선량률 측정결과 최대 $6.78{\pm}0.083{\mu}Sv/h$, $^{99m}Tc$, $^{131}I$ 분배실의 공간선량률이 최대 $9.248{\pm}0.013{\mu}Sv/h$로 나타났다. 또한, $^{18}F$ 분배실의 경우 1m 거리에서 간호사가 IV시 연간 외부피폭선량은 $42.5{\mu}Sv$로 나타났다. 분배실의 분배창을 기준으로 오른쪽 사방향에서 공간선량률이 높게 나타났다. 따라서 방사성의약품을 분배실에서 분배할 경우 방사선 작업종사자의 머무르는 시간을 짧게 해야 하며, 분배창의 오른쪽 사방향의 경우 피폭을 줄이기 위한 분배창의 설계가 필요하며, IV시 작업종사자의 개인피폭선량을 줄이기 위한 최선의 노력이 필요하다고 사료된다.

• 대한방사선기술학회지:방사선기술과학
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• 제45권4호
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• pp.347-353
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• 2022

In this study, the radiation dose rate was measured by time and distance and evaluated whether radiation dose rate was suitable for domestic and international discharge criteria. In addition, the radiation dose emitted from the patient was measured with a glass dosimeter to evaluate the exposure dose if the caregiver stays in the isolated ward by placing a humanoid phantom instead of the caregiver at a distance of 1 m from the patient, on the second day of treatment. After 23 hours of isolation, the radiation dose rates at a distance of 1 m were 20.54 ± 6.21 µSv/h at 2.96 GBq administration and 27.94 ± 12.33 µSv/h at 3.70 GBq administration. The radiation dose rates at a distance of 1 m were 25.90 ± 2.21 µSv/h when 2.96 GBq was administered and 34.22 ± 10.06 µSv/h when 3.70 GBq was administered after 18 hours of isolation. However, if the isolation period is short may cause unnecessary radiation exposure to the third person. The reading of the attached dosimeter from the morning of the second day of treatment until removal was 0.01 to 0.95 mSv, which is a surface dose determined by the International Commission on Radiation Units and Measurements. And the depth dose was 0.01 to 0.99 mSv. On the second day of treatment, even if the patient caregivers stayed in the isolation ward, the exposure dose of the patient family did not exceed the effective dose limit of 5 mSv recommended by the ICRP and NCRP.

• 방사성폐기물학회지
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• 제21권2호
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• pp.183-191
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• 2023

The potential impact of hypothetical accidents that occur during the immediate and deferred dismantling of the Kori Unit 1 steam generator has been comprehensively evaluated. The evaluation includes determining the inventory of radionuclides in the Steam Generator based on surface contamination measurements, assuming a rate of release for each accident scenario, and applying external and internal exposure dose coefficients to assess the effects of radionuclides on human health. The evaluation also includes calculating the atmospheric dispersion factor using the PAVAN code and analyzing three years of meteorological data from Kori NPP to determine the degree of diffusion of radionuclides in the atmosphere. Overall, the effective dose for residents living in the Exclusion Area Boundary (EAB) of Kori NPP is predicted, an it is found that the maximum level of the dose is 0.034% compared to the annual dose limit of 1 mSv for the general public. This implies that the potential impact of hypothetical accidents on human health discussed above is within acceptable limits.

• Journal of Radiation Protection and Research
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• 제37권4호
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• pp.181-190
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• 2012

건축자재에 포함된 천연방사성핵종은 실내공간에 거주하는 일반인의 주요 피폭선원이다. 본 연구에서는 콘크리트 벽체에 존재하는 천연방사성 핵종에 의한 한국인의 실내에서의 외부피폭 방사선량을 평가하였다. 한국인의 주거실태, 실내공간의 크기 등을 고려하여 선량평가를 위한 표준 방의 크기를 결정하였다. 표준 방 이외의 다양한 크기의 공간에 대해서도 선량평가를 실시하였다. 방사선수송 코드인 MCNPX를 사용하여 실내공간에서의 공기 중 흡수선량을 계산하였으며, 이를 이용하여 유효선량률을 계산하였다. 콘크리트 벽체로만 이루어진 $3{\times}4{\times}2.8m^3$ 크기의 표준 방의 경우, 콘크리트 내 우라늄계열, 토륨계열, $^{40}K$ 핵종의 농도에 따라 공기 중 흡수선량률은 0.80, 0.97, 0.08 nGy $h^{-1}$ per Bq $kg^{-1}$이었으며, 유효선량률은 0.57, 0.69, 0.058 nSv $h^{-1}$ per Bq $kg^{-1}$이었다. 실내공간의 크기를 $5-30m^2$로 다양하게 변화시키더라도 천장/바닥 그리고 벽에 의한 상반된 선량률 변화로 인하여 전체 방사선량률은 실내 면적의 변화에 상관없이 거의 일정한 값을 보였다. 실제 국내에서 주로 사용되는 콘크리트 내의 천연방사성 핵종의 농도 및 한국인의 실내공간에서 생활양식 등을 토대로 한국인의 실내공간에서의 외부피폭 방사선량률 및 연간 유효선량을 평가하였다. 콘크리트 내의 우라늄계열, 토륨계열, $^{40}K$ 핵종의 농도가 각각 26, 39, 596 Bq $kg^{-1}$인 경우 공기 중 흡수선량률은 대략 104 nGy $h^{-1}$이었다. 일반인의 실내 점유율이 89%인 경우, 연간 유효선량은 0.59 mSv이었다. 국내의 일반적인 실내공간에서 콘크리트 벽체 내에 존재하는 천연방사성물질에 의한 연간 유효선량은 실내점유율${\times}8760\;h\;y^{-1}{\times}(0.57C_U+0.69C_{Th}+0.058C_K)$을 이용하여 계산할 수 있다.

• Journal of Radiation Protection and Research
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• 제35권1호
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• pp.6-11
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• 2010

Embodying the safety of radioactive waste disposal requires the relevant safety criteria and the corresponding stylized methods to demonstrate its compliance with the criteria. This paper proposes a conceptual model of risk-based safety evaluation for integrating complex potential radiation exposure situations in radioactive waste disposal. For demonstrating compliance with a risk constraint, the approach deals with important exposure scenarios from the viewpoint of the receptor to estimate the resulting risk. For respective exposure situations, it considers the occurrence probabilities of the relevant exposure scenarios as their probability of giving rise to doses to estimate the total risk to a representative person by aggregating the respective risks. In this model, an exposure scenario is simply constructed with three components:radionuclide release, radionuclide migration and environment contamination, and interaction between the contaminated media and the receptor. A set of exposure scenarios and the representative person are established from reasonable combinations of the components, based on a balance of their occurrence probabilities and the consequences. In addition, the probability of an exposure scenario is estimated on the assumption that the initiating external factors influence release mechanisms and transport pathways, and its effect on the interaction between the environment and the receptor may be covered in terms of the representative person. This integrated approach enables a systematic risk assessment for complex exposure situations of radioactive waste disposal and facilitates the evaluation of compliance with risk constraints.

• Journal of Radiation Protection and Research
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• 제31권2호
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• pp.91-96
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• 2006

The effects of Magnetic resonance imaging (MRI) on mouse embryos at the early stage of organogenesis were investigated. Pregnant ICR mice were exposed on day 8 of gestation to MRI at 0.5 T for 0.5 hour to 3 hours. The mortality rates of embryos or fetuses, the incidence of external malformations, fetal body weight and sex ratio were observed at day 18 of gestation. A significant increase in embryonic mortality was observed after exposure to either 0.5 T MRI for 0.5 hour or 2 hours. However, the exposure to MRI for 1 hour or 3 hours did not induce any significant increase in embryonic mortality when compared with control. External malformations such as exencephaly, cleft palate and anomalies of tail were observed in all experimental groups exposed to each MRI. A statistically significant increase of external malformations was observed in all groups treated with 0.5 T MRI for 0.5 hour and 3 hours. The incidence of external malformations in the mice group exposed to 0.5 T MRI for 0.5-hour was found to be higher than those of mice group exposed to 0.5 T MRI for 2 hours. The effects of MRI on the external malformations might not to be dose-dependent. There was no statistically significant difference in fetal body weight and sex ratio among each MRI exposure groups.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3824-3836
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• 2021

Workers' safety from radiological exposure in a 1 ton/day capacity spent resin treatment facility was evaluated according to the operating times and outflow rate due to process related leakages. The conservative annual dose based on the operating times of the workers exceeded the dose limit by at least 7.38E+01 mSv for close work. The realistic dose range was derived as 1.62E+01 mSv-6.60E+01 mSv. The conservative and realistic annual doses for remote workers were 1.33E+01 mSv and 3.00E+00 mSv respectively, which were less than the dose limit. The MWR was identified as the major contributor to worker exposure within the 1 h period required for removal of radioactive materials. The dose considering both internal and external exposures without APF was derived to be 1.92E+01 mSv for conservative evaluation and 4.00E+00 mSv for realistic evaluation. Furthermore, the dose with APF was derived as 7.27E-01 mSv for conservative evaluation and 1.51E-01 mSv for realistic evaluation. Considering the APF for leakage from all parts, the dose range was derived as 1.25E+00 mSv-2.03E+00 mSv for conservative evaluation and 2.61E-01 mSv-4.23E-01 mSv for realistic evaluation. Hence, it was confirmed that radiological safety was secured in the event of a leakage accident.

• Journal of Radiation Protection and Research
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• 제37권2호
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• pp.103-107
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• 2012

PET-CT 검사 환자의 피폭선량 감소를 위한 기초자료 제공의 일환으로 PET-CT 검사 환자의 방사선량률의 변화를 분석하고자 하였다. PET-CT 검사 환자의 방사선량률을 측정한 결과 이론과 같이 방사성의약품이 투여된 환자로부터 거리가 멀수록, 시간이 지날수록 방사선량률은 감소되는 것을 볼 수 있었다. 특히 신체부위에 따라서는 방사성의약품 정맥 주사 즉시인 약 4.17분에서는 흉부, PET-CT 검사 전 배뇨 후인 약 77.47분 이후부터는 두부가 가장 높게 나타났다. 일반화되어 있는 정보와 같이 PET-CT 검사 환자로부터 받는 방사선 피폭량을 감소시키기 위해서는 보호자나 방사선작업종사자가 환자로부터 거리를 멀리하거나 방사능이 감소된 이후의 시간부터 접촉하는 것이 바람직하다. 불가피한 접촉이 필요하다면 가능한 거리는 200 cm이상을 확보하는 것이 바람직하다. 또한 초기에는 흉부, 방사성의약품 투여 후 약 77분 이후부터는 두부에 방사선량률이 높기 때문에 환자 신체적 특징을 고려한 접촉도 함께 이루어진다면 최적화 달성에 도움이 될 것이라고 보여 진다. 본 연구에서 도출된 PET-CT 검사 환자의 거리, 시간, 신체부위에 따른 방사선량률 변화를 알 수 있다는 점에서 연구에 의의가 있다고 본다. 향후 연구에서는 본 연구에서 도출된 결과를 바탕으로 환자 개인특성에 따른 방사선량률의 변화 차이를 분석하여 환자, 보호자, 종사자의 피폭선량 감소에 활용할 수 있도록 지속적인 연구가 수행되는 것이 필요하다고 본다.