Density Meter LB 444 SECTION 2. SYSTEM DESCRIPTION
8
Shieldings
Except for a few special cases, the source is firmly installed into the working
shielding which includes a radiation exit channel to release the active beam to-
wards the detector. The active beam can be shielded during transport and in-
stallation, and when performing service work. This is accomplished by a shutter
mechanism.
The operation of the shutter mechanism and shielding function must be checked
every six months!
2.4.1.1 Shielding Types LB744
Shieldings with manually operated lock
The shielding consists of a cast iron or stainless steel outer shell filled with lead,
except for an exit port blocked by a lead filled moveable shutter. The shutter
mechanism consists of a rotatable lead filled cup connected to the outside of the
housing by means of a shaft, secured to a handle. The lead filling of the cup has
a cylindrical hole. At one distinct and defined position of the handle, the hole and
source holder is aligned, allowing the radioactive beam to reach outside via a
steel cover plate.
This is the “on” position of the device. At all other shaft positions, the beam exit
is blocked by the lead in the cup. The handle, which indicates the open or closed
condition of the shutter, can be secured in the closed position. The handle in
both the open and closed positions prevents access to the source holder.
Cover plate Moveable shutter Shell Lock
Pb
Radiation Position Radiation Source Locking
exit channel "closed" source holder lever
Figure 4: Shielding container type LB744
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