• The Journal of Engineering Geology
• /
• v.23 no.2
• /
• pp.171-186
• /
• 2013

A drilling project was undertaken to characterize the geochemical relationship and the occurrence of radioactive materials at a test site among public-use groundwaters previously known to have high occurrence of uranium and radon-222 in the Daejeon area. A borehole (121 m deep) was drilled and core rocks mainly consist of two-mica granite, and associated with pegmatite and dykes of intermediate composition. The groundwater samples collected at six different depths in the borehole by a double-packed system showed the pH values ranging from neutral to alkaline (7.10-9.3), and electrical conductivity ranging from 263 to 443 ${\mu}S/cm$. The chemical composition of the borehole groundwaters was of the $Ca-HCO_3(SO_4+Cl)$ type. The uranium and Rn-222 contents in the groundwater were 109-1,020 ppb and 9,190-32,800 pCi/L, respectively. These levels exceed the regulation guidelines of US EPA. The zone of the highest groundwater uranium content occurred at depths of 45 to 55m. The groundwater chemistry in this zone (alkaline, oxidated, and high in bicarbonate) is favorable for the dissolution of uranium into groundwater. The dominant uranium complex in groundwater is likely to be $(UO_2CO_3)^0$ or $(UO_2HCO_3)^+$. Radon-222 content in groundwater shows an increasing trend with depth. The uranium and thorium contents in the core were 0.372-47.42 ppm and 0.388-11.22 ppm, respectively. These levels are higher values than those previously been reported in Korea. Microscopic observations and electron microprobe analysis(EPMA) revealed that the minerals containing U and Th are monazite, apatite, epidote, and feldspar. U and Th in these minerals are likely to substitute for major elements in crystal lattice.

• Nuclear Medicine and Molecular Imaging
• /
• v.41 no.1
• /
• pp.22-29
• /
• 2007

Purpose: Metastatic thyroid cancers with I-131 uptake have been known to show no increase of FDG uptake whereas those without I-131 uptake tend to demonstrate increased uptake on PET. In this study, we evaluated the degree of FDG uptake in primary thyroid cancers of papillary histology before surgery. Material & Methods: Forty FDG PET studies were performed on the patients who had papillary cancer proven by fine needle aspiration. The degree of FDG uptake was visually categorized as positive or negative (positive if the tumor showed discernible FDG; negative if the tumor didn't) and the peak standard uptake value (peak SUV) of the papillary thyroid cancer (PTC) were compared with the size of PTC. Results: The mean size of 26 PTC with positive FDG uptake was $1.9{\pm}1.4\;cm(0.5{\sim}5\;cm)$. In 13 PTC with negative FDG uptake, the mean size of those was $0.5{\pm}0.2\;cm\;(0.2{\sim}0.9\;cm)$. All PTC larger than 1cm ($2.5{\pm}1.4\;cm,\;1{\sim}5\;cm$) have positive FDG uptake (peak $SUV=6.4{\pm}5.7,\;1.7{\sim}22.7$). Among the micropapillary thyroid cancer (microPTC; PTC smaller than 1cm), 8 microPTC show positive FDG uptake(peak $SUV=2.9{\pm}1.3,\;1.7{\sim}5.5$), while 13 microPTC show negative finding(peak $SUV=1.3{\pm}0.2,\;1.1{\sim}1.7$). The size of microPTC with positive FDG uptake is significantly larger than that of microPTC with negative FDG uptake ($0.7{\pm}0.1\;cm$ vs $0.4{\pm}0.2\;cm$, p=0.01). Conclusion: All PTCs larger than 1cm show positive FDG uptake in our study. In other words, thyroid lesions larger than 1cm with negative FDG uptake are unlikely to be PTC. So far, only poorly differentiated thyroid cancers are known to show increased FDG uptake. Our results seem to be contradictory to what is known in the literature. Further study is needed to understand better the significance of increased FDG uptake in PTC in relation to expression of NIS and GLUT.

• JOURNAL OF ELECTRICAL WORLD
• /
• s.456
• /
• pp.50-51
• /
• 2014

지난달 13일 열린 원자력안전위원회의 정기회의에서 보류됐던 방사성폐기물처분장(이하 방폐장)에 대한 운영허가 심의가 이달 중순 다시 진행될 예정이다. 이번에도 보류될지, 아니면 허가될지는 미지수다. 그러나 안전성을 충분히 확보했다는 것이 한국원자력환경공단과 원자력안전기술원의 입장인 만큼 머지 않아 운영허가가 이뤄질 것으로 보인다. 그렇다면 현재 원자력발전소 등에서 보관 중인 방폐물은 어떻게 경주에 있는 방폐장으로 옮겨질까. 안전성 확보가 무엇보다 중요한 방폐물을 방폐장까지 완벽하게 운반하는 막중한 임무는 '청정누리호'가 맡고 있다. 청정누리호의 안전 확보 내용을 자세히 들여다본다.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2003.11a
• /
• pp.191-192
• /
• 2003

원자력시설의 사고시 대기중으로 누출된 방사성물질에 의해 오염된 토양으로부터 재배된 농작물로 인한 인체노출은 각종 환경오염물질에 의한 인체영향 연구결과에 보듯이 직접적인 방사능에 의한 인체노출 못지 않게 상당히 중요하다. 이러한 섭식경로를 통한 노출은 각 나라마다 서로 다른 토양조건 및 작물체종류의 다양성등 다른 양상을 보이고 있어, 연구가 수행된 미국이나 유럽등지의 평가방법을 그대로 사용하면 국내의 토양에서 재배되는 농작물이나 이를 이용한 축산물에 따른 한국인의 독특한 섭취양상을 충분히 고려하여 평가하기 어려울 수 있다. (중략)

• Nuclear industry
• /
• v.26 no.9 s.283
• /
• pp.70-78
• /
• 2006

이 보고서는 국제원자력기구(IAEA, International Atomic Energy Agency) 회원국의 요청에 의해 매2년마다 발간되는 “원자력 기술 분석(Nuclear Technology Review)을 요약한 것이며, 2005년 말을 기준으로 발간된 것이다. 원 보고서에 포함된 내용은 원자력 발전, 핵융합, 핵연료, 방사성 동위원소 및 방사선, 관련 연구 개발 등에 대한 오늘과 향후 발전상을 검토한 것이나 여기서는 원자력 발전을 중심으로 요약했다. 보다 궁금한 사항은 IAEA 연례보고서인 2006년 Annual Report에서도 볼 수 있으며 홈페이지인 WWW.iaea.org을 방문하여 영어로 된 보고서를 접할 수 있다. 이 보고서를 요약한 것은 IAEA에서 보는 각국 및 세계 원자력의 현황과 전망을 소개함으로써 국내의 많은 원자력 가족 및 원자력산업에 조금이라도 도움이 되었으면 하는 데 있다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05d
• /
• pp.71-74
• /
• 1996

원자력시설의 비상사태시 대기중으로 방출된 방사성 물질로부터 주변 주민 및 환경이 받는 영향을 신속·정확하게 평가하고 그 피해를 최소화하기 위해 실시간 방사선 피폭해석 시스템을 개발하였다. 수립된 대기 확산모델의 검증 및 정확도 향상을 위하여 야외 확산실험이 수행되었다. 대기 확산모델의 계산결과와 실험을 통하여 관측된 추적자 가스의 농도 분포를 상호 비교한 바 어느 정도 일치하고 있었다. 그러나 일부 경우에서는 관측된 농도값과 계산된 농도값이 차이를 보이고 있는데, 이는 실험 대상 지역에서 충분한 기상 관측을 수행하지 못하여 시간에 따른 풍속의 변화를 확산모델에 자세히 반영하지 못하였기 때문이었다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.10a
• /
• pp.790-797
• /
• 1997

에어로졸 재부유현상은 중대사고 방사선원항 평가에서 그 중요성이 인식되고 있으나 거의 모든 사고해석 코드에서 다루어지지 않고 있다. 따라서 본 연구는 지금까지 제시된 몇가지 유형의 에어로졸 재부유모델을 ORNL에서 실시된 에어로졸 재부유실험 데이터를 이용하여 정확도와 중대사고 해석코드에 적용가능성을 분석하였다. 본 연구에서 고려한 모델은 시간의 멱승함수와 지수함수형으로 표시된 모델들이다. 본 연구에서 분석한 바에 의하면 두 유형에 속하는 대부분의 모델이 재부유량뿐만 아니라 재부유율을 계산하는 데서 실험데이터와 상당한 편차를 보여 현재의 형태로 중대사고 해석 코드에 접목하는 데는 문제가 있는 것으로 분석되었다. 그러나 보다 광범위한 실험데이터를 통한 보완이 이루어진다면 모델식 자체의 간편함으로 접목이 용이할 것이다.

• The Journal of the Acoustical Society of Korea
• /
• v.12 no.4
• /
• pp.14-20
• /
• 1993

본 논문에서는 주변 소음을 감소시키고 표적원의 방사음으로부터 tonal 성분을 추출하기 위한 방법으로서 잡음 정규화 기법에 대하여 연구하였다. 지금까지 알려진 기법들을 정리하였으며, ATW, 최빈치 필터등의 새로운 기법을 도입, 적용하여 그 성능을 평가하였다. 그리고 tonal 성분을 검출하기 위한 임계값 결정을 위해 오경보확률과 검출확률을 시뮬레이션을 통해 구하였다.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.70-74
• /
• 2011

Purpose: In the Nuclear Medicine department of Asan Medical Center, radioactive waste has been disposed of by using several disposal boxes designed for nuclear waste. However, some quantity of radioactivity has been detected occasionally due to some radiologists' carelessness not only from radioactive waste, but also from medical waste such as uncontrolled radioactive waste related to patients, poly gloves or saline solution bottles from radiopharmaceuticals laboratory. Thus, this study is going to suggest a solution to maintain the medical wastes made from controlled areas that can be below maximum permissible surface dose limits by finding the cause of radioactive contamination. Materials and methods: This study was taken place in 17 different places-2 medical wastebaskets in the waiting room, 2 medical wastebaskets in the PET room, 5 medical wastebaskets in the in vitro laboratory and 6 medical wastebaskets in the radiopharmaceuticals laboratory of the East building, 2 medical wastebaskets in the waiting room of the New building of Nuclear Medicine Department in Asan Medical Center from April to August 2010. Mean radioactivity and its standard deviation of each place have been found by measuring surface contamination of medical wastebaskets and backgrounds twice a week, totaling 30 times. An independent t-test of SPSS (Ver. 12.0) statistic program has been used for statistical analysis. Swabs, saline solution bottles and poly gloves collected from each place also measured 30 times, respectively. Results: This study analyzed medical waste and the backgrounds of each place by using survey meter detectors that significant differences of five places did not exist, but existed statistically in twelve places (p<0.05). Also, swabs, saline solution bottles and poly gloves collected from each radioactive waste partly exceed the legal dose limit as a result of measuring by a gamma counter. Conclusion: Backgrounds and the surface doses of radioactive disposal box in all 17 places measured by the survey meter did not exceed the legal dose limit; however, it obviously showed that there were prominent differences in 12 places. Assuming that the cause of the differences was swabs, saline solution bottles and gloves, we examined them by gamma counter, and the results showed remarkably high doses of radioactivity. Consequently, swabs and poly gloves which are normally disposed in the general medical waste box should be disposed in the radioactive waste box furnished by radiopharmaceuticals laboratory. Also, saline solution discharged from radioactive pharmaceutical places is considered as radioactive liquid waste so that it should be disposed of by the septic tank specifically designed for radioactive liquid.

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