Oops

["Grimm, Lawrence" <LGrimm@ADMIN.UCLA.EDU>]

Bit by the "from" bug in my last post.  Here is Jim's message. - Larry Grimm

"Yes, the Georgia irradiator (owned and operated by Radiation Sterilizers,
Inc. (RSI), now SteriGenics) was a wet-storage, dry-irradiation system. It
was designed for use with Co-60, but they swapped over to Cs-137 in the late
80's due to an announced Co-60 shortage. Product was passed through the cell
on a conveyor, and the sources were hoisted out of the water on racks by an
electric hoists.

Initial inventory was around 12.5 MCi (yep, that's MEGA-Curies) ... 252
sources, averaging around 50 kCi each. To the best of our ability to
calculate / inventory, only about 10-20 Ci got out of one source capsule ...
most of that activity remained in the water ... the original filters /
deionizers loaded up quickly (and they were not run continuously) ... but
the cleanup contractor (CNSI / Rust / Rust Environmental / etc. etc. ...
they went through several name changes, but it was the same folks) installed
cleanup demineralizers first thing and that knocked the concentration down
2-3 orders of magnitude ... until the rate of removal equalled the rate that
Cs-137 was being introducted into the pool (on the order of 100 uCi/hr).

One of the sources (about the diameter of a soda can and about 4 times as
long) swelled at one end and leaked ... failure mechanism was never
definitively proven, but my suspicion (personal opinion only) is that the
failure was due to impurities in the CsCl in the source.

The source apparently was leaking for some period of time (on the order of
days to weeks) before the automatic safety systems finally shut things down
so tightly that the "clever operators" couldn't override them (yes, you read
this correctly). By the time we got there, there was about 4-5 Ci of Cs-137
in the pool water (25,000 gallons at 4E-2 uCi/cc, if memory serves) ... we
were reading about 40 mR/hr off the surface of the pool. The problem was
that the source had also leaked while the sources were up, so product was
contaminated, as were the racks, the conveyor (overhead rail), cell walls,
floor, etc. A few employees even took some home with them (we confiscated
several items, which are now resting peacefully at the bottom of a shallow
trench in South Carolina).

As you can imagine, the grease on the conveyor system was a natural trap ...
we had some smears that couldn't even be read with a GM ... you had to
simply dose rate them with an RO-2 with the beta window open (readings well
into the rad range). And you'd be surprised how mobile CsCl is ... it went
EVERYWHERE inside the building ... including up into the ceiling structure. 

I spent 3+ years overseeing the cleanup for the State of Georgia ... and
experience that I wouldn't trade for the world .. but that I wouldn't wish
on my worst enemy either ... 3 years of 7 day weeks, 12 hour days ...
fighting with DOE, and reminding them that they weren't in the middle of a
huge DOE site, that once they walked out the door they were in the
"environment". I spent most of my time watching over them, keeping track of
pool water activity (we had our gamma spec out there and we counted
THOUSANDS of water samples) both with samples and a real-time flow-thru
detection system. I should have written my memoirs at the time ... it was an
AMAZING experience."


Larry Grimm
UCLA EH&S/ Radiation Safety Division
*	lgrimm@admin.ucla.edu   Phone:310/206-0712   Fax: 310/206-9051
*	On Campus: 501 Westwood Plaza, 4th Floor, MS 951605
*	Off Campus: UCLA Radiation Safety Div, 501 Westwood Plaza 4th Fl,
Box 951605, Los Angeles, CA 90095-1605
*	If this email is not RSD business, the opinions are mine, not
UCLA's.

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