• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.2_spc
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• pp.291-303
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• 2020

The Kori-Unit 1 nuclear power plant, which is scheduled to be decommissioned after permanent shutdown, is expected to generate large amounts of various types of radioactive waste during the decommissioning process. Among these, nuclear reactors and internal structures have high levels of radioactivity and the dismantled structure must have the proper size and weight on the primary side. During decommissioning, it is important to prepare an appropriate and efficient disposal method through analysis of the disposal status and the legal restrictions on wastes generated from the reactors and internal structures. Nuclear reactors and internal structures generate radioactive wastes of various levels, such as medium, very low, and clearance. A radiation evaluation indicates that wastes in the clearance level are generated in the reactor head and upper head insulation. In this study, a clearance waste safety evaluation was conducted using the RESRAD-RECYCLE code, which is a safety evaluation code, based on the activation evaluation results for the clearance level wastes. The clearance scenario for the target radioactive waste was selected and the maximum individual and collective exposure doses at the time of clearance were calculated to determine whether the clearance criteria limit prescribed by the Nuclear Safety Act was satisfied. The evaluation results indicated that the doses were significantly low, and the clearance criteria were satisfied. Based on the safety assessment results, an appropriate metal recycle and disposal method were suggested for clearance, which are the subject of the deregulation of internal structures of nuclear power plant.

• Journal of radiological science and technology
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• v.44 no.2
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• pp.109-115
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• 2021

In this study, a physical evaluation of internal radiation exposure in children was conducted using nuclear medicine test(Renal DTPA Dynamic Study) to simulate the distribution and effects of the radiation throughout the tracer kinetics over time. Monte Carlo simulations were performed to determine the internal medical radiation exposure during the tests and to provide basic data for medical radiation exposure management. Specifically, dose variability based on changes in the tracer kinetic was simulated over time. The internal exposure to the target organ (kidney) and other surrounding organs was then quantitatively evaluated and presented. When kidney function was normal, the dose to the target organ(kidney) was approximately 0.433 mGy/mCi, and the dose to the surrounding organs was approximately 0.138-0.266 mGy/mCi. When kidney function was abnormal, the dose to the surrounding organs was 0.228-0.419 mGy/mCi. This study achieved detailed radiation dose measurements in highly sensitive pediatric patients and enabled the prediction of radiation doses according to kidney function values. The proposed method can provide useful insights for medical radiation exposure management, which is particularly important and necessary for pediatric patients.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.600-605
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• 1998

체내방사능 측정시스템의 교정인자는 측정결과에 주요한 요인으로 작용한다. 교정인자는 특정 집단으로부터 표준체위와 표준장기를 도출, 이를 기초로 하여 제작한 펜텀으로부터 구하는 것이 일반적인 방법이다. 그러나 팬텀의 기하학적 구조 및 내부장기의 형상은 특정 집단에 따라 다르므로 이로 인한 측정오차가 발생할 수 있다. 따라서 본 연구에서는 북아메리카 성인남성의 표준자료에 근거하여 제작된 LLNL 팬텀과 일본성인 남성의 표준자료에 근거하여 제작된 JAERI 팬텀을 한국원자럭연구소 폐 카운터를 이용하여 상호비교.분석하였다. 이와 함께 LLNL 팬텀으로 교정된 폐 카운터의 성능시험을 JAERI 팬텀으로 DOELAP 성능시험범주 I, II, III 및 IV에 대해 수행하여 편텀의 구조 및 형상으로부터 발생하는 측정오차를 분석하였다. 비교.분석결과 1.7 cm ~ 3.7 cm 근육등가 가슴벽두께 범위내에서 JAERI 팬텀에 의한 교정인자가 전반적으로 LLNL 팬텀의 것보다 다소 높은 수치를 보였으나 허용수준이었고, 성능시험결과 상대편중은 DOELAP 성능 용인 기준을 만족하였다. 결국 두 팬텀간의 측정오차는 측정 및 체내피폭선량 평가시 수반되는 오차와 비교해 보면 그다지 크지 않은 것으로 결론지울 수 있다. 따라서 LLNL 펜텀으로부터 구한 교정인자를 국내 성인남성의 일상 모니터링에 사용할 경우 측정결과가 다소 과대평가되기는 하나 허용수준으로서 큰 문제가 없는 것으로 나타났다.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.415-427
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• 2021

Korea Institute of Radiological and Medical Sciences has provided various beam irradiation services to researchers using a 50 MeV cyclotron beam line. In particular, since the neutron beam service uses the nuclear reaction between protons and beryllium, the possibility of activation of the irradiated sample increases by using a high current. In this study, MCNP 6.2 and FISPACT-II 4.0 were used to evaluate the possible activation during the 35 MeV 20 ㎂ neutron beam service, which is preferred by the researchers. As a result of the calculation, if the iron, copper, and tungsten samples were irradiated for more than 1 hour, long-lived radioisotopes were produced and their radioactivity exceeded the standard level for self-disposal. Under the conditions of 2 hours of daily irradiation, no activation occurred in the building materials, and the internal exposure of workers due to air activation inside the irradiation room was very insignificant. And when this air was discharged to environment, the radioactivity including this air was also satisfied the emission standard.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.60-67
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• 2004

The exposure dose form recycling of a large amount of the steel scrap from the KRR-1＆2 decommissioning activities was evaluated, and also the clearance level(draft) was derived. The maximum individual dose and collective dose were evaluated by modifying internal dose conversion factor which was based on the concept of effective dose in ICRP 60, applied to the RESRAD-RECYCLE ver 3.06 computing code, IAEA Safety Series 111-P-1.1 and NUREG-1640 as the assessment tool. The result of assessment for individual dose and collective dose is 23.9 $\mu$Sv per year and 0.11 man$.$Sv per year respectively. The clearance levels were ultimately determined by extracting the most conservative value form the results of the generic assessment and specific assessment methodologies. The result of clearance level for radionuclides( $Co^{60}$ , C $s^{l37}$) is less than 1.14${\times}$10$^{-1}$ Bq/g to comply with the clearance criterion(maximum individual dose : 10 $\mu$Sv per year, collective dose : 1 man$.$Sv per year) provided for Korea Atomic Energy Act and relevant regulations.s.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.660-664
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• 2003

The exposure dose form recycling on a large amount of the steel scrap from the KRR-1&2 decommissioning activities was evaluated, and also the clearance level was derived. The maximum individual dose and collective dose were evaluated by modifying internal dose conversion factor which was based on the concept of effective dose in ICRP 60, applied to the RESRAD-RECYCLE ver 3.06 computing code, IAEA Safety Series III-P-1.1 and NUREG-1640 as the assessment tool. The result of assessment for individual dose and collective dose is 23.9 ${\mu}Sv$ per year and 0.11 man$\cdot$Sv per year respectively. The clearance levels were ultimately determined by extracting the most conservative value form the results of the generic assessment and specific assessment methodologies. The result of clearance level for radionuclides($Co^60$, $Cs^137$) is less than $1.67{\times}10^{-1}$ Bq/g to comply with the clearance criterion(maximum individual dose : 10 $\muSv$ per year, collective dose : 1 man$\cdot$Sv per year) provided for Korea Atomic Energy Act and relevant regulations.

• Journal of Radiation Protection and Research
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• v.38 no.2
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• pp.52-59
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• 2013

The internal contamination screening method using gross beta measurement was performed for radioisotope workers. 24 h and spot urine samples from workers of medical isotope production facilities were collected and measured. Most of the results were similar with the background level of gross beta activity except for a specific worker. Gross beta activity was slightly increased in several hours after finishing work. And the environmental factor of production facilities causing internal contamination were estimated based on screening results. The additional detailed internal dose assessment must be followed after the screening for protection of workers. Moreover, a procedure was established to apply a simple internal contamination assessment for radiation workers.

• Journal of Radiation Protection and Research
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• v.33 no.4
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• pp.183-196
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• 2008

The internal dose by food consumption mostly accounts for radiological dose of public around nuclear power plants (NPPs). But, food consumption rates applied to off-site dose calculation in Korea which are the result of field investigation around Kori NPP by the KAERI (Korea Atomic Energy Research Institute) in 1988, are not able to reflect the latest dietary characteristics of Korean. The food consumption rates to be used for radiological dose assessment in Korea are based on the maximum individual of US NRC (Nuclear Regulatory Commssion) Regulatory Guide 1.109. However, the representative individual of the critical group is considered in the recent ICRP (International Commission on Radiological Protection) recommendation and European nations' practice. Therefore, the study on the re-establishment of the food consumption rates for individual around nuclear power plant sites in Korea was carried out to reflect on the recent change of the Korean dietary characteristics and to apply the representative individual of critical group to domestic regulations. The Ministry of Health and Welfare Affairs has investigated the food and nutrition of nations every 3 years based on the Law of National Health Improvement. The statistical data such as mean, standard deviation, various percentile values about food consumption rates to be used for the representative individual of the critical group were analyzed by using the raw data of the national food consumption survey in $2001{\sim}2002$. Also, the food consumption rates for maximum individual are re-estimated.

• Journal of the Korean Society of Radiology
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• v.7 no.5
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• pp.365-369
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• 2013

Intravenous injection is administered with radioactive medical isotopes to detect disease on Positron Emission Tomography (PET). In this case, typically, $^{18}FDG$ (Fluorodeoxyglucose) is used as a radioactive medicine. Cassette equipment is needed to synthesize deoxyglucose with $^{18}F$, produced by medical cyclotron. Production of radioactive medicine creates a lot of radiation, thus Hot Cell is used to shield a secondary radiation. We measured the radiation dosage flowing out of the hot cell during synthesis of $^{18}FDG$ or distribution. The purpose of this study is to provide the information of radiation dosage regarding the occupational exposure that unintentionally occurs during the synthesis of $^{18}FDG$. In conclusion, we confirmed the radiation dosage out of the hot cell during the $^{18}FDG$ synthesis. Especially, we observed that the radiation flowed out through the lead window, attached as a view port. Thus, it is considered that the improvement of a lead window is necessary in order to decrease the occupational exposure during the $^{18}FDG$ synthesis.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.1
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• pp.103-111
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• 2020

Pulling-type cutting devices, which use a diamond wire saw, have been used generally for cutting concrete structures. In this study, a pushing-type cutting device with a collection cover was developed by overcoming the disadvantages of pulling-type devices. In this device, dry or liquid methods can be selected to cool frictional heat. Operation and leakage tests of the dust generated during the dismantling of a concrete structure were carried out, confirming the suitable operation of the fabricated cutting device; the leakage rate was approximately 1.7%. For a conservative evaluation, the internal dose of workers was estimated in dismantling the core center part of biological shield concrete with a specific activity of 99.5 Bq·g^-1. The committed effective dose per worker was 0.25 mSv. The developed cutting device contributed to reducing radioactive concrete waste and minimizing worker exposure due to its easy installation. Therefore, it can be utilized as a cutting apparatus for dismantling not only reinforced concrete structures but also radioactive biological shield concrete in nuclear power plant decommissioning efforts.