• Progress in Medical Physics
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• v.27 no.3
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• pp.146-155
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• 2016

As the probability of exposure to radiation increases due to an increase in the use of radioisotopes and radiation generators, the importance of a radiation safety management field is being highlighted. We intend to help radiation workers with exposure management by identifying the degree of radiation exposure and contamination to determine an efficient method of radiation safety management. The personal exposure doses of the radiation workers at the Korea Institute of Radiological & Medical Sciences measured every quarter during a five-year period from Jan. 1, 2011 till Dec. 31, 2015 were analyzed using a TLD (thermoluminescence dosimeter). The spatial dose rates of radiation-controlled areas were measured using a portable radioscope, and the level of surface contamination was measured at weekly intervals using a piece of smear paper and a low background alpha/beta counter. Though the averages of the depth doses and the surface doses in 2012 increased from those in 2011 by about 14%, the averages were shown to have decreased every year after that. The exposure dose of 27 mSv in 2012 increased from that in 2011 in radiopharmaceutical laboratories and, in the case of the spatial dose rate, the rate of decrease in 2012 was shown to be similar to the annual trend of the whole institute. In the case of the surface contamination level, as the remaining radiation-controlled area with the exception of the I-131 treatment ward showed a low value less than $1.0kBq/m^2$, the annual trend of the I-131 treatment ward was shown to be similar to that of the entire institute. In conclusion, continuous attention should be paid to dose monitoring of the radiation-controlled areas where unsealed sources are handled and the workers therein.

• Journal of Radiation Protection and Research
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• v.34 no.2
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• pp.55-64
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• 2009

In a pressurized heavy water reactor (PHWR), radiation workers who have access to radiation controlled areas submit their urine samples to health physicists periodically; internal radiation exposure is evaluated by the monitoring of these urine samples. Internal radiation exposure at PHWRs accounts for approximately 20 $\sim$ 40% of total radiation exposure; most internal radiation exposure is attributed to tritium. Carbon-14 is not a dominant nuclide in the radiation exposure of workers, but it is one potential nuclide to be necessarily monitored. Carbon-14 is a low energy beta emitter and passes relatively easily into the body of workers by inhalation because its dominant chemical form is radioactive carbon dioxide ($^{14}CO_2$). Most inhaled carbon-14 is rapidly exhaled from the worker's body, but a small amount of carbon-14 remains inside the body and is excreted by urine. In this study, a method for dual analysis of tritium and carbon-14 in urine samples of workers at nuclear power plants is developed and a method for internal dose assessment using its excretion rate result is established. As a result of the developed dual analysis of tritium and carbon-14 in urine samples of radiation workers who entered the high radiation field area at a PHWR, it was found that internal exposure to carbon-14 is unlikely to occur. In addition, through the urine counting results of radiation workers who participated in the open process of steam generators, it was found that the likelihood of internal exposure to either tritium or carbon-14 is extremely low at pressurized water reactors (PWRs).

• The Korean Society of Law and Medicine
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• v.22 no.3
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• pp.97-124
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• 2021

In medical institutions, there are radiation-related workers such as radiological technologists, physicians, dentists, and dental hygienists who handle diagnostic radiation generators. Also, there are work assistants, such as nurses and assistant nurses, who assist in radiation treatment or transfer patients to the radiation examination room. Radiation exposure management for radiation-related workers is carried out under the 「Medical Service Act」, but there is no legal basis for work assistants, etc. And the management of radiation exposure for diagnosis is regulated by the 「Medical Service Act」, and the management of radiation exposure by therapeutic radiation and nuclear medical examination is governed by the 「Nuclear Safety Act」. Thus, to improve the management of radiation exposure for diagnosis, the regulations on radiation exposure management for diagnosis under the 「Medical Service Act」 were compared and reviewed with those of the 「Nuclear Safety Act」. As a result, the main contents are as follows. First, it is necessary to legislate to include nurses, assistant nurses, and clinical practice students who are likely to be exposed to radiation besides radiationrelated workers as subjects of radiation exposure management for diagnosis. Second, when a radiation-related worker for diagnosis is confirmed to be pregnant, the exposure dose limit should be defined. Third, it is necessary to revise the regulations on the types of personal exposure dosimeters in the 「Rules on the Safety Management of Radiation Generators for Diagnostics」. Fourth, it seems that health examination items for radiation-related workers, radiation workers, and frequent visitors should be the same. Fifth, It is necessary to unify and regulate diagnostic radiation and all medical radiation, including therapeutic radiation and nuclear medicine, in one legal system.

• Journal of the Korean Society of Radiology
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• v.18 no.5
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• pp.391-402
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• 2024

In this study, an indicator for setting dose constraints was presented using the frequency distribution of the annual exposure dose per radiation worker. To this end, from January 2017 to December 2019, we surveyed personal dosimeter reading values per month for 13 radiography inspection offices that had reported the establishment of a workplace to move and use radioisotopes, etc. for the purpose of radiographic testing (RT) in Korea, and performed a frequency analysis of the annual exposure dose per radiation worker. In this study, the indicator for setting dose constraints was based on the 95th percentile according to the recommendations of international organizations related to radiation protection. As a result, the dose constraints in the field of RT was set at an average of 5.15 mSv over the three-year investigation period. The nuclear energy-related business operator, if was set its own dose constraints proposed in this study and was operated successfully, were able to manage the exposure dose inequality of 52 people, equivalent to 5% of registered radiation workers, and could expect a reduction in collective dose of 760 man-mSv. Therefore, the nuclear energy-related business operator set its own dose constraints using the indicator for setting dose constraints proposed in this study, will be able to achieve optimization of protection by excluding exposure situations in which a dose level higher than the set dose constraint is expected from the process of establishing a protection plan.

• Journal of Radiation Industry
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• v.9 no.1
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• pp.47-55
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• 2015

Research and investigation is required for the exposure dose of radiation workers to work in the dental hospital as increasing interest in exposure dose of the dental hospital recently accordingly, study aim to minimize radiation exposure by making a follow-up study of individual exposure doses of radiation workers, analyzing the status on individual radiation exposure management, prediction the radiation disability risk levels by radiation, and alerting the workers to the danger of radiation exposure. Especially given the changes in the dental hospital radiation safety awareness conducted the study in order to minimize radiation exposure. This study performed analyses by a comparison between general and dental hospital, comparing each occupation, with the 116,220 exposure dose data by quarter and year of 5,811 subjects at general and dental hospital across South Korea from January 1, 2008 through December 31, 2012. The following are the results obtained by analyzing average values year and quarter. In term of hospital, average doses were significantly higer in general hospitals than detal ones. In terms of job, average doses were higher in radiological technologists the other workes. Especially, they showed statistically significant differences between radiological technologists than dentists. The above-mentioned results indicate that radiation workers were exposed to radiation for the past 5 years to the extent not exceeding the dose limit (maximum $50mSv\;y^{-1}$). The limitation of this study is that radiation workers before 2008 were excluded from the study. Objective evaluation standards did not apply to the work circumstance or condition of each hospital. Therefore, it is deemed necessary to work out analysis criteria that will be used as objective evaluation standard. It will be necessary to study radiation exposure in more precise ways on the basis of objective analysis standard in the furture. Should try to minimize the radiation individual dose of radiation workers.

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.81-87
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• 2020

Background: Kori unit #1 is permanently shut down after a 40-year lifetime. The Nuclear Safety and Security Commission recommends establishing initial decommissioning plans for all nuclear and radwaste treatment facilities. Therefore, the Korea Atomic Energy Research Institute (KAERI) must establish an initial and final decommissioning plan for radwaste-treatment facilities. Radiation safety assessment, which constitutes one chapter of the decommissioning plan, is important for establishing a decommissioning schedule, a strategy, and cost. It is also a critical issue for the government and public to understand. Materials and Methods: This study provides a method for assessing external radiation dose to workers during decommissioning. An external dose is calculated following each exposure scenario, decommissioning strategy, and working schedule. In this study, exposure dose is evaluated using the deterministic method. Physical characterization of the facility is obtained by both direct measurement and analysis of the drawings, and radiological characterization is analyzed using the annual report of KAERI, which measures the ambient dose every month. Results and Discussion: External doses are calculated at each stage of a decommissioning strategy and found to increase with each successive stage. The maximum external dose was evaluated to be 397.06 man-mSv when working in liquid-waste storage. To satisfy the regulations, working period and manpower must be managed. In this study, average and cumulative exposure doses were calculated for three cases, and the average exposure dose was found to be about 17 mSv/yr in all the cases. Conclusion: For the three cases presented, the average exposure dose is well below the annual maximum effective dose restriction imposed by the international and domestic regulations. Working period and manpower greatly affect the cost and entire decommissioning plan; hence, the chosen option must take account of these factors with due consideration of worker safety.

• Journal of Radiation Industry
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• v.18 no.2
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• pp.117-126
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• 2024

This study aims to identify high exposure tasks among the tasks performed in domestic nuclear power plants as a basis for developing training programs to improve the efficiency of workers' work. To this end, we first analyzed the exposure status of radiation work in domestic nuclear power plants. Radiation tasks in nuclear power plants were categorized, collective doses were investigated, and the collective doses were calculated based on the collective doses, and representative high exposure tasks were identified. We found that the collective and individual doses in domestic nuclear power plants are continuously decreasing, but there is an imbalance of exposure among workers. In terms of work classification, nuclear power plants are managed in 236 work codes based on light water reactors and 181 work codes based on heavy water reactors, depending on the work equipment and location. Among the total work codes, 23 codes have an annual average dose exceeding 10 μSv, and based on this, 10 representative high exposure tasks were derived. The representative high exposure tasks were selected as S/G nozzle dam work, S/G debris removal work, nuclear instrumentation system, S/G eddy current detection work, and insulation work. The results of this study are expected to serve as an important basis for reducing the exposure of workers in nuclear power plants and improving work efficiency.

• Journal of Radiation Protection and Research
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• v.31 no.2
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• pp.53-63
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• 2006

The increased risk of cancer with exposure to low-dose radiation was estimated through longitudinal study for radiation workers at the nuclear power plants in Korea. The radiation dose data were collected from the Radiation Safety Management System(RSMS) of the Korea Hydro & Nuclear Power Co., Ltd(KHNP). The cancer risks with radiation exposure were evaluated in terms of relative mortality ratios(RMR) and relative incidence ratios(RIR) to the unexposed employees at the nuclear power plants, and of the standardized mortality ratios(SMR) and standardized incidence ratios(SIR). There were no significant increases of canters of all sites in the exposed group either in RIR[1.08, 95% confidence interval(CI) 0.74-1.58] or in RMR[1.21, CI 0.70-2.08]. Neither SIR[0.81, CI 0.28-0.96] nor SMR[0.86, CI 0.66-1.10] significantly deviated from 1.0 for cancers of all sites. The trend analysis did not identify evident dose-response relationship due to insufficient numbers of the cases. Consequently, it is concluded that increases in cancer risks in the radiation worker group exposed to low doses at the nuclear power plants in Korea are not identified at this time.

• Journal of the Korean Society of Radiology
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• v.18 no.5
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• pp.403-409
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• 2024

This study aimed to provide basic data on the probabilistic effects of radiation by measuring the radiation exposure dose of radiation workers and radiological technology student participating in clinical practice at C University Hospital in Incheon City and analyzing the incidence rate. The subjects of the study were 10 nuclear medicine technologists and 15 radiation oncology worker who worked in the radiological technology area of C University Hospital in Incheon City from January 1, 2023 to December 31, 2023, and 82 radiological technology student who completed the clinical practice course at the same medical institution from July to August. The incidence of adverse effects on the lungs due to radiation exposure dose of radiation oncology worker was shown to be 2.5 per 10,000,000 people for both shallow and deep doses. The nuclear medicine department showed a shallow dose of 2.90 ± 0.61 mSv and a deep dose of 3.02 ± 0.63 mSv, indicating an occurrence probability of 1.5 per 100,000 people. In addition, the radiological technology student classified as frequent visitors showed a shallow dose of 0.99 ± 0.12 mSv and a deep dose of 0.97 ± 0.11 mSv, indicating an occurrence probability of 6.8 and 6.6 per 1,000,000 people. It is thought that this will serve as basic data for minimizing individual exposure dose for radiation workers and analyzing the safety management and probabilistic effects of radiation.

• Journal of Radiation Protection and Research
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• v.47 no.2
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• pp.93-98
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• 2022

Background: This study aims to derive the characteristics of each work type for industrial radiography based on empirical evidence through expert advice and a survey of radiation workers of various types of industrial radiography. Materials and Methods: According to a Korean report, work types of industrial radiography are classified into indoor tests, underground pipe tests, tests in a shielded room (radiographic testing [RT] room test), outdoor field tests, and outdoor large structure tests. For each work type, exposure geometry and radiation sources were mainly identified through the expert advice and workers' survey as reliable empirical evidence. Results and Discussion: The expert advice and survey results were consistent as the proportion of the work types were high in the order of RT room test, outdoor large structure test, underground pipe test, outdoor field test, and indoor test. The outdoor large structure test is the highest exposure risk work type in the industrial radiography. In most types of industrial radiography, radiation workers generally used ¹⁹²Ir as the main source. In the results of the survey, the portion of sources was high in the order of ¹⁹²Ir, X-ray generator, ⁶⁰Co, and ⁷⁵Se. As the exposure geometry, the antero-posterior geometry is dominant, and the rotational and isotropic geometry should be also considered with the work type. Conclusion: In this study, through expert advice and a survey, the external exposure characteristics for each work type of industrial radiography workers were derived. This information will be used in the reconstruction of organ dose for health effects assessment of Korean radiation workers.