[Investigation of radioactivity measurement of medical radioactive waste].
To explore the possibility of which medical radioactive wastes could be disposed as general wastes after keeping them a certain period of time and confirming that their radioactivity reach a background level (BGL), we made a survey of these wastes in several nuclear medicine facilities. The radioactive wastes were collected for one week, packed in a box according to its half-life, and measured its radioactivity by scintillation survey meter with time. Some wastes could reach a BGL within 10 times of half-life, but 19% of the short half-life group (group 1) including 99mTc and 123I, and 8% of the middle half-life group (group 2) including 67Ga, (111)In, and 201Tl did not reach a BGL within 20 times of half-life. A reason for delaying the time of reaching a BGL might be partially attributed to high initial radiation dose rate or heavy package weight. However, mixing with the nuclides of longer half-life was estimated to be the biggest factor affecting this result. When disposing medical radioactive wastes as general wastes, it is necessary to avoid mixing with radionuclide of longer half-life and confirm that it reaches a BGL by actual measurement.
Koizumi
Kiyoshi
K
Tokyo Medical University Hachioji Medical Center. kkoi@tokyo-med.ac.jp
Masuda
Kazutaka
K
Kusakabe
Kiyoko
K
Kinoshita
Fujimi
F
Kobayashi
Kazumi
K
Yamamoto
Tetsuo
T
Kanaya
Shinichi
S
Kida
Tetsuo
T
Yanagisawa
Masamichi
M
Iwanaga
Tetsuo
T
Ikebuchi
Hideharu
H
Kusama
Keiji
K
Namiki
Nobuo
N
Okuma
Hiroshi
H
Fujimura
Yoko
Y
Horikoshi
Akiko
A
Tanaka
Mamoru
M
D006207:Half-Life; D008506:Medical Waste; D011829:Radiation Dosage; D011850:Radioactive Waste; D011874:Radiometry / Q000379:methods*
D008506:Medical Waste; D011850:Radioactive Waste