LOCKING AND UNLOCKING THE A0 NORTH CAVE SHIELDING BLOCKS April 23, 2008
A0 North is a cavity testing facility located at A0. The cavities are frequently changed out and replaced.
AD Radiation Safety is required to be called to lock and unlock the 2 shield blocks in the front of the cave. These blocks are moved to open the cave so they can get the cavities in and out.
The chain is looped through the lifting hooks on the top of the blocks. There are rows of hand-stacked blocks on the top of the front blocks to seal the small gap along the top edge of the blocks. A LOTO tree clamp and a PAD 118 are used to secure the chain.
Inside the cave, the front blocks appear as shown. Ensure the gaps between them are as small as possible. These blocks are not perfectly square so there will be a small 1/16th inch gap at about 5’ from the floor. This is acceptable. Skill and experience are required to set these blocks correctly. The floor is not level, nor are the blocks square, so there “is a trick” to get these blocks installed correctly.
The scarecrow inside the cave is set about a meter away from the dewar. It is not interlocked. It is connected to acnet for data logging, and additionally a local meter is connected for read out. This meter is located above the gate at the entrance.
To LOCK UP CAVE:
1. Ensure the front shielding blocks are properly installed. Ensure the chain is properly looped on the top of the 2 shield blocks, and install the PAD 118 padlock onto the LOTO tree clamping the chain.
2. Ensure the scarecrow is placed on the little yellow footstool inside the cave about a meter away from the dewar.
3. Ensure the cave roof and walls, the cryo penetration on the west side do not appear to be disturbed.
4. Release the “9182” pink-magenta fob key from the BT-5 lockbox in the MCR. Ensure the key is checked back in with the MCR key logger database, then give the key to the crew chief or a helpful operator so it can be returned to the MCR Crew Chief’s key lock box.
5. Close out the Config Log Entry in MISC. When the log entry has been closed out, it should look similar to the following:
Apr 21 2008 08:42:59-
A0 North S&S key 9182 is locked up in the MCR lockbox with RSO #7 because
the shielding will be removed to open the cave. Do not return the key to
service until the shielding has been verified and locked. Roger Zimmermann
-- Wed Apr 23 13:30:31 comment by...Gary Lauten -- shielding
has been verified and locked.
TO UNLOCK CAVE:
1. Lock up the #9182 Pink-magenta fob key into the RSO BT-5 Lockbox in the MCR. Check out the key to your name. RSO authorization will be required for MCR to put this key into your name.
2. Go to the A0 North Cave, and unlock the PAD 118 padlock. Remove the padlock and LOTO tree from the chain and place them both on top of the cave interlock light status box. This box is about 7’ high next to the cave entrance. This location is simply where people expect to find these items when they are needed again.
3. Create a new entry in the config log “MISC” section. Words similar to the following should be used: