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Uranium-containing wafer disposal



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Dear Radsafers,



After having consulted with one of my colleagues and searching the RADSAFE

archives, I find that I need to try and tap the collective wisdom of the

list regarding how to properly dispose of uranium-containing wafers found

in one of our labs.  Apparently, the wafers were sputtered with uranium at

a facility other than our own, but at some point, the wafers found their

way to our site and the potential radioactivity issues went unrecognized.

Based on a rough calculation made by the researcher who brought the

situation to the attention of EH&S, the mass of uranium is estimated to

range between 1 and 10 mg -- probably closer to the lower end.



One reference I consulted (Radiation Protection (3rd Ed.) by Shapiro)

states that in naturally-occurring uranium the respective percentages of

U-238, U-235, and U-234 are 99.72%, 0.72% and 0.0054% and gives respective

specific activities of 3.34E-4 and 2.14E-3, and 6.19 microcuries per

milligram.  If one uses 10 milligrams as the worse case estimate of the

mass of uranium present and assumes that nearly all of that uranium is

U-238, we are then looking at just under 4 nCi of radioactive uranium.   If

I break the estimated quantity of uranium down using the relative

percentages and the respective specific activities, then I have 3.3

nanocuries of U-238, 1.5 nanocuries of U-235, and 3.3 nanocuries of U-234.

When I look at some of the tables in 10 CFR 20, I see limits with respect

to effluent discharges to air, water, and sewers, but no limits applicable

to solid materials other than quantities exempt from labeling (1 nanocurie

for U-234 and U-235 and 100 microcuries for U-238 per Appendix C of 10 CFR

20).  Using the labeling exemption quantities, it would appear that I am

slightly above those limits with respect to U-235 and U-234, but I could

just as well be slightly below those limits if I go with the lower end (for

example, 2 mg) of the estimated quantity range.



Any practical suggestions you might have for addressing the proper disposal

of this particular type of NORM (uranium-containing wafers) would be

appreciated.   If nothing else, it would be helpful to receive comments

from list members on the above assessment and the appropriateness of

applying the labeling exemption quantity limits to this situation.  If not

those limits, than which  limits?



(My apologies for the possible duplication of this posting during RADSAFE's

transition from its previous server location to its current one).



Thank you for your assistance.



Regards,



Stephen



Stephen Hemperly, MS, CIH, CSP

West Region Occupational Health Services (Safety, Industrial Hygiene,

Ergonomics)

Internet address: shemperly@almaden.ibm.com

T/L 457-1375, (408) 927-1375  Fax: (408) 927-2100



Almaden Well-being Services:

http://resalm1.research.ibm.com/projects/gohs_alm/home.nsf/Home?OpenPage

IBM Employee Well-Being:

http://w3-1.ibm.com/hr/us/ohs/gohsweb.nsf/well-being



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Date: Mon, 19 Mar 2001 08:40:38 -0600

From: PBarring@KDHE.STATE.KS.US

Subject: Re: "The Secret Word"



Easy, Sandy.  The whole thing was meant in fun.  Nobody REALLY believes

that changing the name will help.  It is rather funny though that sometimes

it does work.  K-mart is now BigK and they haven't suffered for it.  I am

not ashamed of being a nuclear worker (an NO I don't glow) and I DO post my

name.  The whole thing was a fun Friday thread.  I you want boring tech

talk all the time read RADRAP or the NRC news page.  Most of us here are

here for the discussions and comments serious AND funny.  Please don't take

offense at good natured humor.  If we can't laugh once in a while we'll all

be up on rooftops in no time.  BTW, MY spot across from the Greenpeace

building is reserved, thank you very much.



"Just a voice in the darkness"

Phil



Philip Barringer

Kansas Dept. of Health and Environment

785-296-6342







IMHO this thread should end.



It's bad enough that there are many on this listserver who aren't

willing to identify themselves, unwilling to stand behind their own

statements. Now we have a thread (where some is only sated in

humor) who aren't willing to stand behind the profession they

chose.





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