Enriched tritium analysis

["R. William Field" <bill-field@uiowa.edu>]

Cheryl Baker said:

I was recently asked by my supervisor to explore the possibility of doing
enriched tritium analysis.  I confess total ignorance and am hoping to get
some information through RADSAFE.  First of all, why would anyone need to
see such low levels of tritium, what information is gained?  Is there a
reference
for the technique?  What equipment would be needed and what might the startup
costs be?  We do standard tritium analysis and have a Packard LS counter.
Is anything more elaborate needed?  

Cheryl,

If you perform the tritium enrichment, a normal LSC counter should suffice.
 If you really need to measure (with any confidence) extremely low levels
of tritium then you either need to 1) perform enrichment of the sample, 2)
have count times in the days rather than hours (depends on the background
and efficiency of your LSC) or 3) buy a low level LSC counter (very
expensive).

You asked why anyone would want to see such low levels of tritium.
Monitoring the content of tritium in surficial, ground and oceanic waters
is a great tool for investigating the behavior of the hydrosphere.  For
example, many researchers use both radon and tritium to follow the flow of
groundwater.  We have used the tritium content of aquifer "wells" samples
as a screening tool to decide whether or not we need to analyze further for
contamination from surface sources.  If the water sample shows extremely
low levels of tritium, we know that the water has not been contaminated
with surface runoff (or has not been in contact with another aquifer that
has contact with surface waters).  The tritium content of surface waters
and many aquifers has gone up over 30 fold since the early 1950s because of
nuclear testing.  If we sample an aquifer and it has a tritium unit of 1 or
2, we have a certain degree of confidence that the water in that aquifer
has not been in contact with surface waters.

I would be glad to answer additional questions.  I also have several
references for tritium enrichment.  The correct equipment makes the method
reasonably easy.

Please contact me directly.  I do not have your email address.

Bill Field
bill-field@uiowa.edu     




******************************
R. William Field, Ph.D.
Division of Epidemiology
Department of Preventive Medicine
  and Environmental Health
N222 Oakdale Hall
University of Iowa
Iowa City, Iowa 52242
319-335-4413 (phone)
319-335-4747 (fax)
mailto:bill-field@uiowa.edu
******************************