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국일현,박춘득,구자호 한국방사선산업학회 2015 방사선산업학회지 Vol.9 No.2
The iridium disc, generally used in industrial radiography, is examined to find thefracture morphology and fine particles remaining on the shear blank surface. Randomly selected1,200 discs were observed under a scanning electron microscope tilted more than 45°. Fracturesurfaces are classified into three groups: (1) surface fall-out, (2) fracture on the edge and (3)multi-step brittle fracture, which shows the mutual relationship between the fracture morphologyand remaining particles. Fracture particles were removed by cleaning the discs in a ultrasonicbath with acetone and collected at the bottom. Removed number of the particles were countedfor each different group of fracture surfaces. Followings are conclusions: (1) About 80.5% ofdiscs (966/1,200), have sound plastic shear surfaces with particles remained. (2) About 2% discsaccompany surface fall-out’s having large particles tens of μm, which is stable not to be pulledout even after the considerably long time of ultrasonic cleaning. (3) About 5% discs contain thefractures on the edge and the particles are removed thoroughly within 30 minutes. (4) 234 discsout of 1,200 discs have multi-step fracture surfaces whose particles never removed in a shortperiod of time but come out very slowly. Such a disc having multiple-step fracture is attributedto the promate cause to the ‘leaker’. It is noted here that the discs having mutiple-step fracturesshould be treated separately with special care, and it is need to study how to treat them.
Ir-192 방사선원의 밀봉 용접부 품질에 미치는 저항용접 공정변수의 영향
한인수,손광재,이영호,이유황,이준식,장경덕,박울재,박춘득,Han, In-Su,Son, Kwang-Jae,Lee, Young-Ho,Lee, You-Hwang,Lee, Jun-Sig,Jang, Kyung-Duk,Park, Ul-Jae,Park, Chun-Deuk 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.1
Ir-192 radiation sealed sources are widely employed to the therapeutic applications as well as the non-destructive testing. Production of Ir-192 sources requires a delicate but robust welding technique because it is employed in a high radioactive working environment. A GTA(Gas Tungsten Arc) welding technique is currently well established for this purpose. However, this welding method requires a frequent replacement of the electrode, which results in the delay of the production to take a preparatory action such as to isolate the radiation sources from the working place before getting access to the welding machine. Hence, a resistance welding technique is considered as an alternative method of the GTA welding technique. The advantages of resistance welding are high welding speed and high-rate production. Also it has very long life of electrode comparing to GTA welding. In this study, the resistance welding system and proper welding conditions were established for sealing Ir-192 source capsule. As a results of various experiments, it showed that electrode displacement can be employed as a indicator to predict welding quality. We proposed two mathematical models(linear and curvilinear) to estimate electrode displacement with process parameters such as applied force, welding current and welding time by using regression analysis method. Predicting results of both linear and curvilinear model were relatively good agreement with experiment.
고농축 표적을 이용한 비파괴검사용 192Ir 미세초점선원 개발
손광재,홍순복,장경덕,한현수,박울재,이준식,김동학,한근대,박춘득 한국비파괴검사학회 2007 한국비파괴검사학회지 Vol.27 No.1
192Ir small-focal source has been developed by using the HANARO reactor and the radioisotope production facility at the Korea Atomic Energy Research Institute (KAERI). The small-focal source with the dimension of 0.5mm in diameter and 0.5mm in length was fabricated as an aluminum-encapsulated form by a specially designed pressing equipment. For the estimation of the radioactivity, neutron self-shielding and -ray self-absorption effects on the measured activity was considered. From this estimation, it is realized that 192Ir small-focal sources over 3 Ci activities can be produced from the HANARO. Field performance tests were performed by using a conventional source and the developed source to take images of a computer CPU and a piece of a carbon steel. The small-focal source showed better penetration sensitivity and geometrical sharpness than the conventional source does. It is concluded from the tests that the focal dimension of this source is small enough to maximize geometrical sharpness in the image taking for the close proximity shots, pipeline crawler applications and contact radiography. 하나로와 동위원소 생산시설을 활용하여 비파괴검사용 192Ir 미세초점선원의 생산기술을 개발하였고 현장적용시험을 통하여 개발된 제품의 성능을 확인하였다. 직경 0.5mm × 높이 0.5mm인 선원의 개발을 위해 알루미늄 캡슐 압착 방법 및 장치를 개발하여 표적을 제작하였으며, 하나로를 이용한 방사능 생성량을 평가한 결과 약 3.0 Ci 방사능의 선원 제조가 가능함을 확인하였다. 또한 컴퓨터 CPU 및 탄소강에 대한 비파괴검사를 실시하여 투과도계 감도 및 기하학적 불선명도가 비교 대상 선원에 비해 우수함을 확인하였다. 이 선원의 초점크기는 기존의 선원에 비해 매우 작기 때문에 근접 및 접촉촬영과 튜브-튜브시트 용접부의 비파괴검사에 있어 기하학적 불선명도를 최소화 할 수 있을 것이다.주요용어: 미세초점선원, 방사선투과검사, 이리듐-192, 하나로