New radiographic testing technique using low energy gamma ray (Yb-169)

Book · Tue Aug 01 04:00:00 EDT 1995

OSTI ID:86111

Ooka, N; Yamabayashi, H ^[1]; Takano, E; Fujioka, K ^[2]

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1. Japan Atomic Energy Research Inst., Ibaraki (Japan)
2. Mitsubishi Heavy Industries, Co., Ltd., Kobe (Japan)

The authors have been developing technology for producing new {gamma}-ray source of ytterbium-169 (Yb-169) and applying it to the inspection of components in fabrication process. The Yb-169 source emits {gamma}-rays of effective energy 200 keV which is lower than that of iridium-192 (Ir-192), so that it is quite useful to apply the Yb-169 to non-destructive tests for welding of thin steel pipes under 10mm thick. The sealed Yb-169 source of nominal intensity of 180GBq (5Ci) in pellet size of 1.0 mm in diameter and 1.0mm in length, which is encapsulated with titanium, has been used to radiographic examination for butt welded joints of pipes. A lead shield of 5mm thick reduces the radiation intensity of Yb-169 to 1/100, so that the {gamma}-ray projector for the Yb-169 source can be made smaller and more compact. In the double wall single image method, the smaller source to film distance (SFD) results in the better quality of images and the fewer consumption of films. The area to be controlled to avoid radiation exposure of workers can also be reduced to about 2 meters from the irradiator of Yb-169, that is, about 1/5 of that for Ir-192. The weight of the {gamma}-ray projector would be 5kg or less, about 1/2 of that of Ir-192. This enables inspectors to do the nondestructive tests simultaneously with other work during daytime. Regarding the quality of images, Yb-169 distinguishes two more fine wires with a standard wire penetrometer than Ir-192 when it is applied for steel plates of 1--12mm thick. Applying it to the double wall method for steel pipes of 10.8--60.5mm in outer diameters, Yb-169 also distinguishes two more fine wires compared with Ir-192.

• OSTI ID: 86111
• Report Number(s): CONF-9505104--; ISBN 0-87170-548-6
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
42 ENGINEERING
EXPERIMENTAL DATA
GAMMA RADIATION
GAMMA RADIOGRAPHY
GAMMA SOURCES
IRIDIUM 192
NONDESTRUCTIVE TESTING
PIPES
WELDED JOINTS
YTTERBIUM 169