SENSseries LB 480 Level measurement
BERTHOLD TECHNOLOGIES GmbH & Co. KG
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Volume 1 10 Source Replacement
1
10 Source Replacement
Radioactive sources may be replaced only by a competent firm that
has a service license to handle radioactive materials.
10.1 Radiation Exposure during Source
Replacement
It is important to calculate the possible radiation exposure even
before mounting or dismantling rod sources. An exact calculation is
possible using the equation described in chapter 9.2.3.
The anticipated working hours should be split up in work in the
direct vicinity of the shielding during mounting and dismantling the
source holders and work with the unshielded source while fixing and
dismantling the source and the source holder. The dose obtained
while working in the vicinity of the shielding and the dose obtained
while working with the unshielded source have to be calculated sep-
arately and added up.
A rather simplified estimation is possible, provided the work is pre-
pared well. Based on the assumptions of a mean distance of 0.5 m
for the whole body radiation and the time you are working with the
unshielded source of 6 minutes (= 1/10 hour), the radiation expo-
sure can be calculated for different activities (A) as follows:
Dose D = A x 0.15 for Co-60
Dose D = A x 0.04 for Cs-137
Enter the activity in MBq; the dose is calculated in μSv.
For multi-part rod sources, the estimated radiation exposure has to
be multiplied with the number of source parts.
Using a pocket dosimeter with direct reading, measure the accu-
rate radiation exposure during this work, even if the radiation
exposure lies below the detection limit of dosimeters.
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