Next: 4.1.2.2 Restricted Access
Previous: Obtaining Required Safety Training
Users and staff working on the accelerator site are protected from the
dangers associated
with the prompt ionizing radiation that the accelerator beam produces by
Jefferson Lab 's Personnel
Safety System or PSS. The PSS keeps ionizing radiation out of areas where
people are
working, and keeps people out of areas where ionizing radiation is present.
For example, when
the PSS is in the Restricted Access state, people are allowed to work in
the hall and measures
are in place to prevent delivery of beam to the hall. If the PSS is in the
Beam Permit state, beam
can be delivered to the hall and measures are in place to prevent people
from entering the hall.
The Personnel Safety System includes Run/Safe boxes which are located
throughout Hall
A, and approximately every 100 feet in the linac. A run/safe box has three
positions: Safe,
Operational, and Unsafe. When the hall is in Restricted Access, the
run/safe box will be in the
Safe position. While in this position, the PSS prevents delivery of beam to
the hall. Before
beam can be delivered, the hall must be swept to ensure that no one is left
inside. During the
Sweep, each run/safe box is moved to the Operational position in
preparation for Beam Permit. After the sweep has been completed and the
hall is placed in the
RF Power Permit state, the run/safe box will show Unsafe. Each box has an
emergency stop
button. If you see the box in the Unsafe position, you are in danger of
receiving high levels of
ionizing radiation. Immediately press the emergency stop button, exit the
hall, and call the
Machine Control Center Crew Chief at extension 7050.
There are a total of five states for the Hall A Personnel Safety System:
Restricted Access,
Sweep, Controlled Access, RF Power Permit, and Beam Permit.
Next: 4.1.2.2 Restricted Access
Previous: Obtaining Required Safety Training
10/13/1997