3) calculate an average value of measured gamma radiation ambient background
DER (further – gamma background) when there is no reference radiation source. To do it,
wait no less than 600 s from the moment the instrument was placed on the dosimetric
equipment and then take 5 DER measurement readings at 150 s interval (no less). Then
calculate average DER meaning of gamma background
, by formula (5.1). One
segment of analogue scale must be indicated.
– i-th meaning of gamma background DER measurement, Sv/h;
4) move the dosimeter on the dosimetric unit so that geometrical center of the
detector coincides with the reference point, where reference DER value is 3,0 μSv/h, and
expose the dosimeter to irradiation. At that two segments of analogue scale must be
indicated;
5) wait at least 100 s after exposure starts, then take 5 DER measurement readings
(at 60 s interval at least). Then calculate average DER value
– i-th dosimeter reading when measuring DER in j-th tested point;
6) repeat measurements for points where reference DER value is 80,0; 800 μSv/h.
At that three segments of analogue scale must be indicated if DER is 80,0 μSv/h and four
segments if DER is 800 μSv/h;
7) move the dosimeter on the dosimetric unit so that geometrical center of the
detector coincides with the reference point, where reference DER value is 8,0 mSv/h;
8) expose the dosimeter to irradiation, at that five segments of analogue scale must
be indicated;
9) wait at least 60 s after exposure start, then take 5 DER measurement readings
(at 20 s interval at least) and then calculate average DER value by
by formula (5.2);
10) repeat the measurement for the reference point where reference DER value is
80 mSv/h. At that six segments of analogue scale must be indicated;
Detector geometrical center
Figure 5.1 – The way for dosimeter with phantom be placed on the verification
dosimetric unit
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