76
3.2.4.2.3 Place the device in the УКПН-1М carriage holder so
that the mechanical center of neutron beam coincides with the one of
the device’s neutron detector. Place the УКПН-1М carriage holder
with the device in the position, where neutron radiation from
239
Pu-
Be ensures pulse count rate from the neutron detector within a 10 –
20 s
-1
range. Make sure that the alarm of neutron radiation is
triggered.
3.2.4.2.4 Switch off the device according to OM 2.3.3.2.
3.2.4.3 Calculation of the main relative permissible error limit
during gamma radiation DER measurement.
3.2.4.3.1 Prepare the testing equipment УПГД-3Б (hereinfater –
УПГД-3Б) according to its Operating Manual.
Place the device in the УПГД-3Б carriage holder so that the
mechanical center of gamma beam coincides with the mechanical
center of the device’s gamma detector.
Note 1.
The mechanical center of the gamma detector is labeled
"+" on device’s back cover.
Note 2.
The distance between the mechanical center of the source
and the mechanical center of the device’s gamma detector is
considered to be the distance between the mechanical center of the
source and the plane, which is perpendicular to the direction of
gamma quanta beam propagation, and passes through the mechanical
center of the device’s gamma detector in this plane.
Switch on the device. Turn off the sound and vibration alarms of
threshold levels.
Make five measurements of gamma background DER
)
10
(
*
i
H
in УПГД-3Б with an interval of 10 seconds. Register the obtained
readings in the report.
Calculate the average value of
)
10
(
*
H
, µSv/h, by the formula: