• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1368-1375
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• 2016

A radiological safety assessment study was performed for the transportation of low level radioactive wastes which are temporarily stored in Korea Atomic Energy Research Institute (KAERI), Daejeon, Korea. We considered two kinds of wastes: (1) operation wastes generated from the routine operation of facilities; and (2) decommissioning wastes generated from the decommissioning of a research reactor in KAERI. The important part of the radiological safety assessment is related to the exposure dose assessment for the incidentfree (normal) transportation of wastes, i.e., the radiation exposure of transport personnel, radiation workers for loading and unloading of radioactive waste drums, and the general public. The effective doses were estimated based on the detailed information on the transportation plan and on the radiological characteristics of waste packages. We also estimated radiological risks and the effective doses for the general public resulting from accidents such as an impact and a fire caused by the impact during the transportation. According to the results, the effective doses for transport personnel, radiation workers, and the general public are far below the regulatory limits. Therefore, we can secure safety from the viewpoint of radiological safety for all situations during the transportation of radioactive wastes which have been stored temporarily in KAERI.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• The Journal of the Korean dental association
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• v.52 no.3
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• pp.132-138
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• 2014

The emergence of Cone Beam Computed Tomography(CBCT) in the late 1990s represented an innovative advancement in the field of dental and maxillofacial radiology because it greatly reduced the radiation exposure to patients and offered 3D images easily. The 3D information generated by this technique brings the potential of improved diagnosis and treatment planning for a wide range of clinical applications in dentistry. The use of CBCT includes diagnosis and surgical assessment of the orofacial hard tissue lesions, dental implant treatment planning and postoperative evaluation, TMJ assessment, diagnosis of craniofacial fracture, orthodontics, endodontics, and so on. All CBCT examinations should be justified on an individualized needs. The clinical benefits to the patient for each CBCT scan must outweigh the potential risks associated with exposure to ionizing radiation. CBCT scans should be taken with initially obtained medical and dental histories of patients and a close clinical examination. CBCT should be considered as an imaging alternative of other conventional radiography in cases where the anatomical structures of interest may not be seen. The smallest possible field of view(FOV) and the lowest setting of tube current and scan time should be chosen, and the entire images scanned should be interpreted by a qualified expert.

• Journal of Radiation Protection and Research
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• v.35 no.2
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• pp.57-62
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• 2010

Maintenance on the water chamber of steam generator, the change of pressurizer heater, the removal of pressure tube feeder, and so on during outage in nuclear power plants (NPPs) has a likelihood of high radiation exposure to whole body of workers even short time period due to the high radiation exposure rates. In particular, it is expected that hands would receive the highest radiation exposure because of its contact with radiation materials. In this study, field tests on extremity dose assessment of radiation workers for contact works with high radiation exposure were conducted during the maintenance periods in Korean pressurized water reactors (PWRs) and pressurized heavy water reactors (PHWRs). In this field test, radiation workers were required to wear additional TLDs on the back and wrist, and an extremity dosimeter on fingers including a main TLD on the chest, while performing maintenance. As a result, it was found that the equivalent dose for fingers was distributed in the fixed range of deep dose and the equivalent dose for wrists.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.17-21
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• 2015

Recently, As people's interest in the health of teeth is increased in the medical field changed into aging society, the number of times for the radiological diagnosis is increased. It can be said that the radiation exposure dose of Korean population is increased. It is also growing concern about radiation exposure. Therefore, the basic data for the dental panoramic X-ray system, its investigation and measuring the radiation dose is needed. In this study, we used ALOKA PDM-117 dosimeter and estimated a two-dimensional dose distribution of the dental panoramic X-ray system (VATEC Pax-400). Dose evaluation about the distribution is confirmed from the point of radiation exposure of a patient. Dose distribution of the dental panoramic X-ray system irradiated chin and the facial region to high dose as well as the parts of teeth. It was founded that the eye lens which are sensitive to radiation are exposed to unnecessary radiation, considering the effect of scattered radiation. The results of this study will be used more accurate dose assessment in a variety of object size and location of measuring dose.

• Journal of Radiation Protection and Research
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• v.48 no.2
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• pp.90-99
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• 2023

Background: Quantitative risk assessments should be accompanied by uncertainty analyses of the risk models employed in the calculations. In this study, we aim to develop a computational code named SUMRAY for use in cancer risk projections from radiation exposure taking into account uncertainties. We also aim to make SUMRAY publicly available as a resource for further improvement of risk projection. Materials and Methods: SUMRAY has two versions of code written in R and Python. The risk models used in SUMRAY for all-solid-cancer mortality and incidence were those published in the Life Span Study of a cohort of the atomic bomb survivors in Hiroshima and Nagasaki. The confidence intervals associated with the evaluated risks were derived by propagating the statistical uncertainties in the risk model parameter estimates by the Monte Carlo method. Results and Discussion: SUMRAY was used to calculate the lifetime or time-integrated attributable risks of cancer under an exposure scenario (baseline rates, dose[s], age[s] at exposure, age at the end of follow-up, sex) specified by the user. The results were compared with those calculated using another well-known web-based tool, Radiation Risk Assessment Tool (RadRAT; National Institutes of Health), and showed a reasonable agreement within the estimated confidential interval. Compared with RadRAT, SUMRAY can be used for a wide range of applications, as it allows the risk projection with arbitrarily specified risk models and/or population reference data. Conclusion: The reliabilities of SUMRAY with the present risk-model parameters and their variance-covariance matrices were verified by comparing them with those of the other codes. The SUMRAY code is distributed to the public as an open-source code under the Massachusetts Institute of Technology license.

• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.152-161
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• 1986

외부방사선피폭(外部放射線被曝)으로 인한 위험(危險)의 평가(評價)와 관련된 량(量) 및 개념(槪念)의 동향(動向)과 미해결(未解決)된 문제점(問題點)들에 대하여 살펴보았다. 특히 ICRU 39의 실용량(實用量)에 근거(根據)한 선량환산인자(線量換算因子), 선질계수(線質係數)의 재정의(再定義), 성별(性別)에 따른 위험(危險)의 차이(差異) 그리고 기타조직(其他組織)의 선정문제등(選定問題等)에 대하여 구체적(具體的)으로 논(論)하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.10
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• pp.1017-1026
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• 2013

Four countries are participating in exposure assessment for Mobi-Kids Study. Each country evaluates RF and ELF exposure from mobile phones considering telecommunication system and environment in the corresponding area. The results will be used to determine accumulation exposure level of each subject in case and control groups to assess the potential carcinogenic effects of childhood and adolescent exposure to radio frequency(RF) and extremely low frequency( ELF) from mobile phones on the central nervous system. This paper analyzes exposure types of mobile phones which have been used in Korea for about 10 years, based on Mobi-Kids protocol. It includes investigation of mobile phone models released in the domestic market, design of numerical phone models to represent each exposure type, and measurement of ELF radiation from mobile phones.

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.121-126
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• 2002

The work presents a realistic human exposure assessment of indoor radon released from groundwater in a house. At first, a two-compartment model is developed to describe the generation and transfer of radon in indoor air from groundwater. The model is used to estimate radon concentrations profile of indoor air in a house us]ng by showering, washing clothes, and flushing toilets. Then, the study performs an uncertainty analysis of model input parameters to quantify the uncertainty in radon concentration profile. In order to estimate a daily internal dose of a specific tissue group in an adult through the inhalation of such indoor radon, 3 PBPK(Physiologically-Based Pharmaco-Kinetic) model is developed. Combining indoor radon profile and PBPK model is used to a realistic human assessment for such exposure. The results obtained from this study would be used to the evaluation of human risk by inhalation associated with the indoor radon released from groundwater.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.394.2-394
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• 2002