Radioactivity in Air and Rainwater
* Yuguru SUZUKI
1. Gross #- activity in Air
a. Dry filter paper method
The air sampler was carefully placed on the compass
deck, in order to avoid contamination by sea water, and
was continuously operated during the entire cruise.
Dust samples were collected on Whatman #41 filter paper
(5.5 ¢
> every 24 hours.
Suction volume of the
sampler was approximately 30/#@/min.
To measure the activity of the samples, an end window
type GM counter with a DC-1C scaler was used. The
distance between the mica window (1.46 mg/cm2 thick) and
the samples was approximstely 1 cm.
The counting
efficiency, calibrated with ?5Zr—7°Nb, was 6.6%.
Results obtained are shown in Table 1.
b. Gummed paper method
Sampling for fallout in the air by this method
was also carried out on the compass deck. The samples
were collected after the paper was exposed for approximately 24 hours. Measurements of the grossf-activity
on the gummed paper samples were not conducted aboard
the ship.
2. Gross #-activity in Rainwater
.
Rainwater was collected by using funnels (100 emé<
surface area) which were placed in polyethylene or glass
bottles set on the compass deck. 10-100 ml of the
samples collected were evaporated on a porcelain plate,
then placed on a counting dish. Measurement for
grossB--activity were conducted in the same manner
described in paragraph la.
in Table 2.
* National
Institute
Results obtained are shown
of Radiological
Sciences
SIRSPATee”