R. Lewis 5/7/03
The basic NTF Elevator
Access Plate Key configuration is shown below.
There are two color-coded lock sets, shown as the red and blue donuts in
the diagram, which control latches, shown as dashed rectangles in the
horizontal (locked) position, which latch into slots of the NTF Treatment Room
wall. The locks are such that when the
key is turned to unlock a latch, the key is captured in the lock until the
latch is moved back to the locked position.
The key arrangement prior
to 5/7/03 (and the way it had been for several years) was a PAD 549 core in
each lock, as shown in Table 1. The PAD
549 series has only one key, which has been kept in the MCR Crew Chief cabinet
as “NTF ELEVATOR ACCESS PLATE KEY #1 (9191)” with a red fob. With this arrangement, to unlock the plate to
access the area under the elevtaror platform, the key
was inserted into one of the locks and turned, then the plate was pulled away
from the wall slightly so the latch could be moved back to the locked position
without being captured in the wall slot so that the key could be removed and
used to unlock the second lock.
The above unlocking
procedure required some flexing of the plate and was generally considered
cumbersome. NTF personnel expressed a
desire to change to a system of two keys, one to unlock each of the locks. The keys would be kept in the MCR CC Cabinet.
To address this concern,
the following plan was implemented on 5/7/03 which provides a separate key for
each of the plate locks: The PAD 549 core was
removed from the blue (right side) lock and replaced with a PAD 550 core; The
PAD 550 key was then added to the MCR CC Cabinet as “NTF ELEVATOR ACCESS PLATE
KEY #2” (9192) with a blue fob. The KEY
#2 has the same requirements as KEY #1 (which remains in the CC Cabinet as is),
namely Confined Space and Rad Worker training and RSO permission. The final arrangement is reflected in Table 1
below.
TABLE 1 |
Red Lock (left side) |
Blue Lock (right side) |
Configuration prior to
5/7/03 |
PAD 549 |
PAD 549 |
Configuration after
5/7/03 change |
PAD 549 |
PAD 550 |
8/8/2006 It doesn’t matter whether linac is running or not. Just as there is no control over access to the treatment room with floor up or down, it wouldn’t matter if someone was under the floor. The RSO should obtain the NTF enable key from the MCR for safekeeping and ensuring no NTF beam is possible while they’re making the confined space access under the floor, so that proper protocol for additional safety is followed. They cannot run beam to NTF without the enable key.