Vega SHLM MI4, Руководство по эксплуатации, Страница: 40 / 72

40 48642-US-150527
Safety Shield
The source holder is transported with a safety shield in place to maintain the
source holder in the safest condition possible. This safety shield is installed on the
flange-end of the source holder. The shield limits the radiation field exiting from
flange end of the holder to very low levels and should remain in the holder until the
source holder is being prepared for mounting to the vessel. A 9/16
"
open end
wrench is required to remove the four hex bolts that hold the shield in position. A
minimum clearance of 4
"
is needed to remove the shield.
Figure 5.1
Safety Shield
Inserting Sources into a Dry Well
In this particular installation, it is necessary to insert the source capsules into a dry
well from the bottom of the tank. The source capsules are pushed up into the well.
As the capsules are moving from the source holder into the vessel, they are
unshielded. Therefore, moving the sources into the well should be done as rapidly
as possible. No direct contact with the sources is necessary and must not occur
under any circumstance.
After the sources are in the well, perform a radiation survey around the tank and
the source holder. The radiation field inside the vessel can be greater than 100
mRem/hr (1 mSv/hr) when mounting an unshielded source in a vessel. Posting
The shielding in the space between the source holder and the
source well may be minimal. You should not allow the sources to
remain in this area; the sources should be either inside the source
holder or inside the source well.
!
NOTE