tritium, nasty?

[Lester Slaback <Lester.Slaback@NIST.GOV>]

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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