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02.2017
9 Radiation Protection Volume 1
9.2.2 Radiation Exposure during Installation of the
Shielding
The shieldings of measuring systems are usually designed such that
the limit of the control area is in a given distance (in most cases less
than one meter) around the shielding, and it does not matter
whether point or rod sources are being used and how high their
activity is. A simplified calculation of the radiation exposure during
installation of the shielding is possible with sufficient accuracy using
the dose rate data printed on the type plate, measured in 1 m dis-
tance from the shielding. The radiation exposure D can be calcu-
lated according to the following formula:
D = DR x t x 4
D = accumulated dose during assembly in Sv
DR = dose rate on the type plate of the shielding in µSv/h
t = time needed for the installation with shielding in h
If the work process is prepared well, you may expect a working
time of less than 20 minutes to perform work such as installation of
the shielding or operating the shutter.
Calculation example
DR = 3µSv
t = 20min (1/3h)
D = 3 x 1/3 x 4 = 4µSv/h
If we compare this dose with the permissible annual dose of 1 mSv
for persons who are not exposed to radiation on their job, this work
may be carried out 250 times per year by one and the same person.