The stand was used for transferring UCX11 targte from TH to SHC. The stand wit target was craned down from TH into SHC last week and stayed there over weekend. Chad and I removed the stand out of SHC yesterday. It was heavily contaminated. RPG and I spent more than 3 hours to clean this stand. See the emails I pasted below for detail information.
Thanks, David, for letting me know about this. Here are survey results after my afternoon in Target Hall:
I spent 1.5 hours on additional decon of the stand, crane hook, and area around where David was doing the decon, finding up to 10k cpm (44-2) on some parts at first. Danka came to help after a bit (THANK YOU, DANKA) and we left the items covered in plastic and surveyed the area. Contamination survey results are as follows, numbers are units of cpm on the 44-2/RM14:
Tacky mats inside TMH door: 6000/2000
Tacky mats in hall before TMH door: 200/0
Tacky mats at boot box: 8000/4000
My booties: 50/0
Air sample at the decon area: 50/60 (also 100 cpm on alpha probe)
Floor swipes post-decon of floor: 0/0
Early results from a 10 min assay of the tacky mats shows predominantly Kr-85, Be-7, Sr-85, Rb-83, and Sr-82. A longer assay is underway.
The following measurements were made using the checking cave at the boot box (units of cpm):
David's respirator cartridges: 160
David's respirator: 0
Davids tank suit and booties: 1200
My suit: 100
My respirator: 0
The rags used for the decon work were contained in a bag and left behind the silos by the DST. This bag measured 240 uSv/h OC and 2 uSv/h at 0.5m
Thanks,
Andrew
On 11/24/2014 12:57 PM, David Wang wrote:
Hi all, The UCx#11 target transferring stand is moved back from SHC to TH. However, the stand was heavily contaminated. On the first Windex clean up towel, the counts directly shoot over the 500K counts which is the maximum scales on both RM14 and 44-2. After almost 2 hours, more than 20 times cleaning up with Windex spray and paper towel wipe , the counts dropped below 300 now. It is extremely difficult to clean up this stand. I dont think we should move the target this way again unless we have a solution on the contamination clean up. The stand is still hanging on the crane, and waiting for RPG checking. Thanks David |