RE: tritium, nasty?

["Minnema, Douglas" <Douglas.Minnema@ns.doe.gov>]

Les and others,

We in DOE are discovering that you need to be a little careful in your
dealings with tritium.  While by and large you are correct, we are currently
studying concerns with stable tritium compounds (STC's).  These are
generally found either in the forms of tritiated metals or organically bound
tritium.  While most of our STCs are intentionally created for various
reasons, we are also encountering it in the forms of dust, rust, and
contaminated pump oils.

The problems with these materials is that they are often in respirable form,
and can have much longer residence times in the body because of lower
dissolution rates.  Bioassay techniques become very complicated or
ineffective.  STCs are also much harder to detect, since we normally put
dust filters on our air samplers.  

I don't want to imply that this is a crisis-type situation, but we are
actively studying the impact of these concerns on our practices, and the
potential for encountering these materials during D&D activities.

Doug Minnema, PhD, CHP
Defense Programs
<Douglas.Minnema@ns.doe.gov>



> -----Original Message-----
> From:	Lester Slaback [SMTP:Lester.Slaback@NIST.GOV]
> Sent:	Wednesday, March 08, 2000 10:42 AM
> To:	Multiple recipients of list
> Subject:	tritium, nasty?
> 
> Franz said...
> Since tritium is a very nasty radionuclide, because it diffuses
> everywhere,
> the laboratory will be pretty contaminated.
> 
> I would like to mildly disagree.
> 1. Bioassay and dose assessment is the simplest of all nuclides.
> 2.  Instrumentation sensitivity (via liquid scintillation) is orders of
> magnitude better than any limits of concern.
> 3.  Air sampling sensitivity is at least 0.00001 DAC (via cold traps).
> 4.  Ion chamber air monitoring is intrinsically simple (in terms of
> calibration), and sensitive to at least .02 DAC.
> 4.  smear sensitivity is similarly way below limits.
> 5.  the most common form (oxide) is water soluble (by definition).
> 6.  It does not present any external dose issues (except in multicurie
> amounts).
> 7. It has a rather short biological half life, and in fact can be further
> shortened rather easily if needed.
> 
> So I would not take the minor quirk in its character of diffusion into
> surfaces as sufficiently egregious as to label it 'nasty'.  It is just a
> minor idiosyncrasy that, once appreciated, can generally be managed.
> 
> And regarding the lab contamination issue, tritium serves as a classic
> example for discussing the issue of what level of contamination represents
> an issue of concern.  Simply using the benchmark of higher energy beta
> emitters that are transported like dirt, e.g., as particles, clearly is an
> inappropriate model.  Maybe it is the only counter example, but clearly
> tritium oxide is a form that needs its own contamination limits.  And any
> limit set on a dose basis would be such a high number that lab
> contamination for the vast majority of research uses of tritium would be a
> non-issue.
> 
> signed: Founding member of the Prevention of Tritium Abuse Society.
> 
> Disclaimer:  the above are the personal musings of the author, and do not
> represent any past, present, or future position of NIST, the U.S.
> government,
> or anyone else who might think that they are in a position of authority. 
> Lester Slaback, Jr.  [Lester.Slaback@NIST.GOV] 
> NBSR Health Physics 
> Center for Neutron Research 
> NIST
> 100 Bureau Dr.  STOP 3543 
> Gaithersburg, MD  20899-3543 
> 301 975-5810 voice
> 301 921-9847 fax
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