• Journal of Radiation Protection and Research
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• v.29 no.1
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• pp.57-63
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• 2004

As a part of In-service Inspection works in a nuclear power plant, Eddy Current Testing through all the outage of nuclear power plants has been controlled by the radiation management. From the case study about the periodical ECT work, the exposed dose rate of worker has announced over the organized dose rate before the radiation work, it affects the personnel exposed dose management and radiation work permit issue. It is not easy to get some information about ECT related working hours, scope of work and how many workers to forecast the radiation working and the predict dose exposure. It should be need the data accumulation about ECT related radiation work to prepare the ALARA achievement and the radiation work plan for dose mitigation. We can discuss a few information about ECT related radiation working issue for the application of predict dose exposure on this paper.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.17-25
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• 2005

Since the safety of nuclear power plant has been becoming a big social issue the exposure dose of radiation for workers has been one of the important factors concerning the safety problem. The existing calculation methods of radiation dose used in the planning of radiation work assume that dose rate does not depend on the location within a work space thus the variation of exposure dose by different work path is not considered. In this study, a modified numerical method was presented to estimate the exposure dose during radiation work in radwaste storage considering the effects of the distance between a worker and sources. And a new numerical algorithm was suggested to search the optimal work path minimizing the exposure dose in pre-defined work space with given radiation sources. Finally, a virtual work simulation program was developed to visualize the exposure dose of radiation doting radiation works in radwaste storage and provide the capability of simulation for work planning. As a numerical example, a test radiation work was simulated under given space and two radiation sources, and the suggested optimal work path was compared with three predefined work paths. The optimal work path obtained in the study could reduce the exposure dose for the given test work. Based on the results, tile developed numerical method and simulation program could be useful tools in the planning of radiation work.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.237-241
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• 2013

The gamma energy distributions at the major working places during refueling outage of Korean PWR nuclear power plants were measured. In order to estimate the dose reduction effect of a lead vest, Monte Carlo calculation method was used. For the simulations, the MIRD-V phantom with a lead vest was formed and exposed to the measured radiation field. The average measured gamma energy is lower than that of standard which is generally applied to radiation protection procedures. For the efficient use of a lead vest and achievement of radiation protection purpose, it is necessary to estimate the energy distribution of radiation field at working places.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.427-429
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• 2004

본 연구에서는 국내 방사선 작업 종사자의 연간 피폭량 중 상당부분(30%)를 차지하는 원자력 발전소 작업 종사자의 방사선 피폭량을 3차원 그래픽 시뮬레이션 기술 및 Java 프로그래밍과 수치해석 방법을 이용하여, 보다 안전한 작업 계획 수립에 필요한 작업 동선에 따른 방사선 피폭변화에 대하여 연구하였다. 원자력 발전소의 방사성 폐기물 처리 시설에 대해 3차원 그래픽으로 모델링 작업을 수행하고, 가상공간에서 선원과 작업자와의 거리 및 시간에 따른 방사선 피폭량을 수치 해석적으로 계산하였다. 선원의 종류에 따른 특정감마선($\tau$상수)을 입력하여 가상 작업 시뮬레이션 동안의 피폭선량을 평가하였으며, 시간에 따른 가상 작업자의 위치와 이동거리, 방사선 피폭량 등의 결과데이터 파일을 이용하여 작업 결과를 분석하였다.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.174-175
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.278-279
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• 2009

• 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.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.38-38
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• 2003

목적 : 방사선 수술의 목적은 병소에 최대한의 방사선을 조사하고, 주위의 정상조직에는 가능한 적은 양의 방사선을 조사하는 것이다. 이러한 목적을 만족시키기 위해 방사선 수술계획자는 계획시 isocenter의 위치와 개수, 콜리메이터 크기를 변화시켜 가며, 주어진 병소에 맞는 선량분포를 획득해 방사선 수술효과를 최대화시키는 수술계획을 수립한다. 본 연구에서는 다양한 모양의 병소에 대해 자동적으로 isocenter를 위치시켜 수술 계획시 도움이 될 수 있도록 임의의 병소 모델들에 대해 위의 변수들을 변화시켜 가며 얻어지는 선량분포를 비교 분석하였다. 방법 : 본 연구에서는 임의로 정의한 계산 영역내에 다면체를 병소로 가정하여 연구를 수행하였다. 방사선 수술시 하나의 isocenter에서 얻어지는 선량분포는 구형으로 근사할 수 있으므로 하나의 isocenter를 구로 근사하여, 각 병소 모델 내에 콜리메이터 크기를 변화해가며 가능한 많은 영역을 포함하도록 isocenter를 배치시켰다. 이후 구형선량모델을 사용해 선량분포를 획득하여 병소와 정상조직간의 DVH(Dose Volume histogram)와 각 병소 모델에 대한 통일 평면상의 선량분포를 비교 분석하였다. 결과 ; 임의의 다양한 종양 모델에 대한 50%의 등선량 곡선내에서 세 가지의 빔관련 변수들을 변화시킨 결과, 종양이 없는 정상 조직에서는 선량분포가 극히 낮았으며, 콜리메이터의 크기에 따른 isocenter 의 개수가 변화하는 것을 확인할 수 있었고, 이 경우 한 종양모델에서의 깊이에 따른 선량 분포는 크게 차이가 나지 않았다. 그리고, isocenter의 개수가 변화함에 따라 선량곡선이 변하는 것을 확인할 수 있었다. 결론 : 빔관련 변수인 콜리메이터 크기, isocenter 개수, 거리등은 어느 일정 정도를 넘기면, 병소내 선량 분포에 크게 기여하지 않는다는 점을 감안하여 빔관련 변수들을 최소로 고려하므로써 계획시 소모되는 시간 과 노력을 많이 줄일 수 있을 것이며, 또한 각 병소 모델에 대한 최적의 구형선량모델에서 공통적인 규칙성을 찾는 것과 실제 병소의 모양을 간단한 모양으로 근사화 시킨다면 자동적 선량모델을 이루는데 많은 도움이 되고, 이로 인해 효율적인 치료계획작업이 이루어질 것이라 사료된다.

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.176-183
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• 2009

Maintenance on the water chamber of steam generator 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, characteristic analysis of inhomogeneous radiation fields for contact operations was conducted using thermoluminescent dosimeter (TLD) readouts from the application tests of two-dosimeter algorithm to Korean NPPs in 2004. It is regarded that inhomogeneous radiation fields for contact operations in NPPs are dominated by high energy photons. In addition, field tests for workers who participated in maintenance on the steam generator during outage at Ulchin NPPs in 2009 and pressure tube replacement at Wolsong NPPs in 2009 were conducted to analyze radiation fields and to estimate the extremity dose. As a result, radiation fields were dominated by high energy photons.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.162-167
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• 2015

Although the perfomance indicators of the nuclear power plants in Korea show optimal, it requires detailed analysis and discussion centered on the radiation dose. As analysis methods, analysis on the radiation dose of nuclear power plants over the past five years was assessed by comparing the relevant radiation dose of radiation workers and per capita average annual radiation dose of the world's major nuclear power stations was also analyzed. The radiation workers over the annual radiation dose limit of 50 mSv were not. The contrast ratio of the radiation exposure according to the reactor type was the normal operation of PHWR was 6.2% higher than those of the PWR. This shows the radiation work of PHWR during normal driving operation is much more than those of PWR. According to the Performance Indicators of the World Association of Nuclear Operator, the annual radiation dose per unit in 2013 showed 527 man-mSv of Korea is the best country among the major nuclear power generating states, the world average was 725 man-mSv. The annual per capita radiation dose is about 80% less than 1 mSv of the public dose limit and also the average per capita dose showed a very low level as 0.82 mSv. Workers in related organizations showed 1.07 mSv, the non-destructive inspection agency workers showed 3.87 mSv. The remarkable results were due to radiation reduced program such as development of radiation shielding and radiation protection. In conclusion, the radiation exposured dose of nuclear power plants workers in Korea showed a trend which is ideally reduced. But more are expected to be difficul and the psychological insecurity against the operation of the nuclear power plants is existed to the residents near the nuclear power plants. So the radiation dose reduction policy and radiation dose follow up study of nuclear power plants will be continously excuted.