Re: Low Temperature Thermal Desorption Units

[Steve Deitch <StephenD@compuserve.com>]

In response to the inquiry relative to low temperature thermal desorption
as a treatment for mixed waste, NSSI has found that thermal desorption is
useable for most materials which contain radionuclides other than Tritium
and Carbon 14.  We have been able to remove a wide range of organics and
water from radiocontaminated matrices using low temperature and vacuum. We
have also used higher temperatures and vacuum to separate Mercury from
Radium contaminated solids. 

The process is primarily applicable to D coded mixed waste and D and F
coded debris mixed wastes. One needs to keep in mind that for P, U, or F
coded wastes other than debris, when one thermally removes the compound
responsible for the code such removal does not eliminate the P, U, or F
code from the materials which remain behind.  These residues will continue
to carry the codes as a result of the derived from rule.

With Tritium, thermal desorption has very limited applicability as Tritium
has a tendency to exchange with all of the organic species and water within
a waste matrix. When one attempts to desorb the water from an organic, the
water will contain some level of Tritium. 

Carbon does not exchange to any perceptable degree but one must know the
actual chemical form of the carbon in order to determine whether thermal
desorption will be effective. 

Thermal desorption in many states is treatment and as such is subject to
the limitations the state may place on the use of the technology and may
require treatment permits. 

If additional information or clarification is of interest, I can be reached
on line, or contact me, or Bob Gallagher at NSSI, at 713 641-0391.

Steve Deitch