Results of questionaire survey for the measurement of radioactivity in waste water

A questionaire for radioactivity in waste water was sent to 388 facilities, including 158 medical facilities, and all (100%) answered. Information requested included: (1) kinds and annual usage of unsealed RI, (2) measuring method of radioactivity in waste water, (3) kinds of measuring instruments and the detection limits, (4) prior treatment of measurement materials, (5) level of radioactive waste exhausted during 3 months, (6) personnel and time per month required for radioactivity measurement, (7) problems and comments in waste water management, and (8) kinds of facilities. A total of 36 unsealed RI were used. The most commonly used RI was I-125 (n=240), followed by H-3 (n=189) and P-32 (n=179). Annual level of RI was 4 GBq or less in 90% of the facilities. The most common method for measuring radioactivity was sampling method (n=241). The most common instrument for measuring radioactivity was a gamma counter for I-125 (45% of the facilities), and a liquid scintillation counter for P-32 (80%) and for C-14 and H-3 (90%). The detection limits for I-125 exceeded the radioactivity limits in 24% of the facilities. The amount of sampler was 5 cc or less in 80% of the facilities. Prio treatment was not carried out in 62.7%. Prior treatment methods reported were enrichment, evaporation, pH adjustment, and sedimentation. Half of the facilities exhausted 10 cm3 or less of waste water during 3 months. The number of persons engaging in radioactivity measurement per month was reported to be one in 282 facilities (87%). (N.K.)