• Journal of Radiation Protection and Research
• /
• v.30 no.4
• /
• pp.161-165
• /
• 2005

The gamma-ray dose rates in air at 233 locations in Korea have been determined. The contribution to the gamma-ray dose rates in air due to the presence of $^{232}Th-series,\;^{238}U-series\;and\;^{40}K$ is as follows: 47.3% $(36\;nGyh^{-1})\;^{232}Th-series$ 14.5% $(11\;nGyh^{-1})\;^{238}U-series$ and 38.2% $(29\;nGyh^{-1})\;^{40}K$. The mean gamma-ray dose rate theoretically derived from $^{232}Th-series,\;^{238}U-series\;and\;^{40}K\;was\;76{\pm}17\;nGyh^{-1}$. This corresponds to an annual effective dose of $410\;{\mu}Sv$ and an annual collective dose of 18900 person-Sv for all provinces under study. The results have been compared with other global radiation dose.

• Journal of Radiation Protection and Research
• /
• v.30 no.4
• /
• pp.185-196
• /
• 2005

Although medical exposure from diagnostic radiology procedures such as conventional x-rays, CT and PET scans is necessary for healthcare purposes, understanding its characteristics and size of the resulting radiation dose to patients is much of worth because medical radiation constitutes the largest artificial source of exposure and the medical exposure is in a trend of fast increasing particularly in the developed society. Annual collective doses and per-caput effective doses from different radiology procedures in Korea were estimated by combining the effective dose estimates per single medical procedure and the health insurance statistics in 2002. Values of the effective dose per single procedure were compiled from different sources including NRPB reports, ICRP 80, MIRDOSE3.1 code and independent computations of the authors. The annual collective dose reaches 27440 man-Sv (diagnostic radiology: 22880 man-Sv, nuclear medicine: 4560 man-Sv) which is reduced to the annual per-caput effective dose of 0.58 mSv by dividing by the national population of 47.7 millions. The collective dose is far larger than that of occupational exposures, in the country operated 16 nuclear power plants in 2002, which is no more than 70 man-Sv in the same year. It is particularly noted that the collective dose due to CT scans amounts 9960 man-Sv. These results implies that the national policy for radiation protection should pay much more attention to optimization of patient doses in medicine.

• Journal of Radiation Protection and Research
• /
• v.8 no.2
• /
• pp.41-46
• /
• 1983

Annual collective dose within 50 miles radius of Ko-ri I reactor site due to normal airborne effluent discharges in 1979 has been estimated by AIRDOS-EPA computer code. Gaussian plume equation is used for estimation of both horizontal and vertical dispersion of radionuclide release into the atmosphere. Also, radionuclide concentrations in meat, milk, and fresh produce consumed by near-by population are estimated by coupling the output of the atmospheric transport models with the USNRC terrestrial food chain models. Annual collective doses are found to be $3.348{\times}10^{-1}$ whole body manrem and 84.95 thyroid manrem. Whole body manrem calculated by AIRDOS-EPA computer code do not differ greatly from that calculated by GASPAR computer code, but value for thyroid manrem have been estimated lower than that calculated by GASPAR computer code.

• Journal of Radiation Protection and Research
• /
• v.28 no.2
• /
• pp.137-143
• /
• 2003

Annual radiation dose limit to radiation worker was substantially lowered in Korea by the adoption of 1990 recommendations of the International Commission on Radiation Protection (ICRP 60) in its legislation. On the other hand, radiation management environment in nuclear power plants is getting more worse because of the accumulation of radiation sources inside the system and the frequent need for maintenance according as the operation years of nuclear power plants increase. Therefore, Korea Hydro & Nuclear power Co., Ltd. (KHNP) has established a long-term 10 years plan from 2001 to 2010 for the reduction of radiation dose to workers. The plan is aimed for the reduction of annual dose per unit averaged over 5 years from 0.9 man-Sv in 2001 to 0.75 man-Sv in 2010 by radiation source reduction, equipment/tool improvement or new equipment development for easy maintenance, and the improvement of administration and system.

• Journal of Radiation Protection and Research
• /
• v.29 no.2
• /
• pp.141-150
• /
• 2004

Dose rate characteristics of cosmic radiation field at flight altitudes were analyzed and the route doses to the personnels on board due to cosmic-ray were calculated for Korean-based commercial international airline routes using CARI-6. Annual individual doses to aircrew and the collective effective dose of passengers were estimated by applying the calculated route doses to the flight schedules of aircrew and the air travel statistics of Korea. The result shows that the annual doses to aircrew, around 2.62 mSv, exceed the annual dose limit of public and are comparable to doses of the group of workers occupationally exposed. Therefore it is necessary to consider the frequent flyers as well as the aircrew as the occupational exposure group. The annual collective dose to 11 million Korean passengers in 2001 appeared to be 136 man-Sv. The results should be modified when the dose rates of cosmic radiation at high altitude are revised by taking into account the changes in the radiation weighting factors for protons and neutrons as given in ICRP 92.

• Journal of Radiation Protection and Research
• /
• v.28 no.2
• /
• pp.145-154
• /
• 2003

By optimizing the radiation protection the collective dose and individual dose could be reduced during YGN #4 $5^{th}$ outage in 2001. The collective doses for the two high radiation jobs decreased to 85% and 65% of expected doses. The proportion of workers with low dose (below 1mSv) exposure increased 4% while the proportion of workers with over 3mSv and 5mSv exposure are decreased to 2%, 1% respectively. But none is exposed over 8mSv for the annual dose. To aid decision of utilizing the robot, cost- benefit analysis was performed and reasonable point was proposed to use the robot. For the first time job, repeated ALARA meeting and mock up training were implemented to set up working procedure by identifying the trouble. To easily set up standard procedure, mockup process was videotaped and reviewed during ALARA meeting. Monitoring is a good approach to chase radiological working condition such as working time, dose rate. behavior of workers, especially for high radiation work. Those data were estimated and adjusted from the stage of work planning to mock up. At the stage of actual work the monitoring data were compared to the estimation and recorded to database. This database will not only be used as a powerful tool for dose optimization at the following outage but also as a guideline to dose constraint set up for optimization for each specific situation.

• Journal of Radiation Protection and Research
• /
• v.23 no.3
• /
• pp.149-157
• /
• 1998

An analysis has been performed to estimate the additional number of workers and the additional collective dose in man-cSv which would be required, nuclear industry-wide as a result of reducing individual dose limit. This analysis can be extended to the reduction in the dose limits recommended by ICRP Publ.60 and BEIR V report as well as the proposed dose limits by regulatory authorities. An industry-wide database was employed in the analysis based on a summary of industry-wide occupational radiation exposure compiled by the Korea Radioisotope Association. Correlation model was employed to compute the affects of setting specific annual individual dose limits. In this study, we have addressed worker non-productivity while in the radiation environment on a parametric or 'sensitivity analysis' basis. This alleviates the need for developing such data underlying a summation of many individual tasks at many nuclear facilities. It has the advantage that very low non-productivity assumptions can readily be defended as conservative, in that it is difficult to approach such low worker non-productivity factors even in the best of environments in any industry. On a per facility basis, for calendar year 1997, the number of workers required would be increased from 231 workers to 269 workers and collective man-cSv dose would be also increased by approximately fourteen percent if the individual dose limit was reduced to 2 cSv/y and an individual worker non-productivity fraction of 0.1 is assumed.

• Journal of Radiation Protection and Research
• /
• v.30 no.4
• /
• pp.175-183
• /
• 2005

Dose distribution of Korean radiation workers classified by occupational categories was analyzed. Statistics of the occupational radiation exposure(ORE) in 2002 of the radiation workers in diagnostic and dental radiology were obtained from the Korea Food and Drug Agency(KFDA) who maintains the database for individual radiation dose records. Corresponding statistics for the rest of radiation workers were obtained by processing the individual annual doses provided by the Korea Radioisotope Association(KRIA) after deletion of individual information. The ORE distribution was classified in term of 28 occupational categories, annual individual dose levels, age groups and gender of 52733 radiation workers as of the year of 2002. The total collective dose was 66.4 man-Sv and resulting average individual ORE was 1.26 mSv. Around 80% of the workers were exposed to minimal doses less than 1.2 mSv. However, it appeared that the recorded doses exceeded 20 mSv for 43 workers in the industrial radiography and for 147 workers in the field of radiology. Particularly, recorded doses of 23 workers in radiology exceeded the annual dose limits of 50 mSv, which is extraordinary when the working environment is considered. It is uncertain whether those doses are real or caused by careless placing of dosimeters in the imaging rooms while the X-ray units are in operation. No one in the workforce of 16 operating nuclear power plant units was exposed over 20 mSv in 2002. Number of workers was the largest in their 30's of age and the mean individual dose was the highest in their 20's. Women were around 20% of the radiation workers and their average dose was around one half of that of man workers.

• Journal of radiological science and technology
• /
• v.33 no.3
• /
• pp.231-237
• /
• 2010

Computed tomography (CT) has been established as an important diagnostic tool in clinical medicine and has become a major source of medical exposure. A nationwide survey regarding CT examinations was carried out in 2007. Thanks to the appeasement policy regulating the import of CT scanners, there are 1,825 CT scanners across the country as of the end of March 2010, which means that we have 36.8 CT scanners per one million people. The annual number of examinations was 3.29 million, the number of examinations per 1000 population was 68. The most part of examinations was abdomen and pelvis. and the collective effective dose was in these parts. The effective dose per one population was evaluated as 0.952 mSv.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.2_spc
• /
• pp.317-325
• /
• 2020

The Korea Radioactive Waste Agency plans to expand the storage capacity of radioactive waste by constructing a radioactive waste inspecting building to solve the problem of the lack of inspection space and drum-handling space in the radioactive waste receipt and storage building for the first-stage disposal facility. In this study, the exposure doses of radiation workers that handle new disposal containers for decommissioning waste in the storage areas of the radioactive waste inspecting building were calculated using the Monte Carlo N-particle transport code. The annual collective dose was calculated as a total of 84.8 man-mSv for 304 new disposal containers and an estimated annual 306 working hours for the radiation work. When the 304 new disposal containers (small/medium type) were stored in the storage areas, it was found that 25 radiation workers should be involved in acceptance/disposal inspection, and the estimated exposure dose per worker was calculated as an average annual value of 3.39 mSv. When the radiation workers handle the small containers in high-radiation dose areas, the small containers should be shielded further by increasing the concrete liner thickness to improve the work efficiency and radiation safety of the radiation workers. The results of this study will be useful in establishing the optimal radiation working conditions for radiation workers using the source term and characteristics of decommissioning waste based on actual measurements.