Online ISSN : 1884-4111
Print ISSN : 0033-8303
ISSN-L : 0033-8303
Volume 69 , Issue 12
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  • Yoshiharu Miyazaki, Go Yoshida, Kazuyoshi Masumoto, Hiroshi Matsumura, ...
    2020 Volume 69 Issue 12 Pages 365-373
    Published: December 15, 2020
    Released: December 15, 2020

    Herein, we present the case study of the decontamination of highly activated concrete in the accelerator room. The activated cyclotron room for pharmaceutical for the positron emission tomography (PET) in the Medical and Pharmacological Research Center Foundation (Ishikawa, Japan) was decontaminated. The contact dose rates of the concrete walls, floor, and ceiling were measured at 50 cm mesh using a NaI survey meter. The depth profiles of specific activity in the concretes were obtained by core boring at seven different places. The activated concrete regions were estimated in detail based on the relationship between the measured contact dose rates and depth profiles of the specific activity. The activated concrete was chipped and removed based on the estimated activated region. Then, through remeasurement, it was confirmed that the removal of the activated concrete was completed. The measurement of the contact dose rate using the NaI survey meter could determine the removal depths of the concrete at short range mesh. This contributed to the reduction of radioactive waste.

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