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Re: Follow up to RE: Tritium Absorption in Materials
Tritium is hydrogen and except for the isotope effect on reaction rate,
behaves chemically like hydrogen. Tritiated water will exchange rapidly
with the hydrogen of water in the air, so I always worked with tritiated
ionic substances (and deuterated ones) in a nitrogen atmosphere in a glove
box. The isotope effect on reaction rate is that the rate is inversely
proportional to the square root of the molecular mass ratio. It's only
noticeable in small molecules where the hydrogen (or deuterium or tritium)
is a significant fraction of the molecular mass, like H2 gas, water,
methane. I doubt there would be a noticeable effect with HCl. I worked
with tritiated and deuterated glycine (H2N-CH2-COOH, or tritiated,
T2N-CH2-COOT, and some totally tritiated) and never observed any effect on
the chemistry except the annoying tendency to exchange. Tritium is a beta
emitter, and I doubt any radiolysis would be sufficient to be noticeable. I
was in fact radiolyzing glycine using a Co-60 source, and breaking the bonds
I was trying to break wasn't easy (I worked with glycine single crystals).
The other phenomena you mention would be the same with tritiated water as
with ordinary H2O.
Ruth Wiener
ruth_weiner@msn.com_
-----Original Message-----
From: Emil Murat <kerrembaev@yahoo.com>
To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
Date: Wednesday, February 07, 2001 9:42 PM
Subject: Follow up to RE: Tritium Absorption in Materials
>Greetings,
>
>I have not seen any replies on this subject for a
>while and started wondering if it went into private
>emails or else.....
>
>Bharat,
>
>You brought up an interesting in many ways problem.
>Personally, I have not done experiments with Tritium
>as you've done and my knowledge of this topic is
>limited to assumptions which are based on knowledge of
>some chemistry and some thermodynamics.
>
>1. I would think that from the beginning Tritium is
>behaving as a part of what you have: water, base or
>acid and it will be involved in the same basic
>chemical organic/inorganic reactions as a H-2, of
>course.
>H-3 Polarization does/does not effect
>on a organic reaction??... It should...
>
>
>2. Absorption rate equals to a SUM of chemical
>reaction rate and water diffusion rate and it depends
>on given conditions; temperature would be the
>dominating factor for the chemical reaction.
>
>3. Transfer/Diffusion rate you can find from
>Thermodynamics of liquids and gases; H2O will be
>penetrating as liquid and as vapor/gas depends on
>material structure and temperature, pressure.
>If you have some kind of equilibrium: relatively long
>exposure time, chemical reactions are balanced balance
>It should be "easier" to figure out the constants with
>no dynamics.
>
>4. There may be a/ need to look at "Radiolysis" (Free
>Radicals Production)if you had a high Radiation Flux
>in your environment. I am not sure how H3 will behave
>in that case.
>
>5. The chemical reactions with the absorbing material
>will be case-specific and environment-specific.
>
>Inorganic: Metals - Corrosion in the water(no
>stainless steel) Acid environment-...
>
>Concrete, plastics, rubber, wood: - stable in the
>water.
>Graphite - Pretty much chemically inert but H-3
>polarization, electrostatics will effect on its
>absorption/penetration rate at molecular level.
>
>
>5. I would suggest you to do, if you have not done it
>yet, search literature and perform balk estimates; to
>have a some theoretical basis for your experimental
>data.
>
>6. As soon as you do that, you may see correlations
>with you experimental results.
>
>It is really hard to determine with out some estimates
>which will be the major driven mechanism (Chemistry or
>Mechanical Transfer) in the process and which will be
>neglegable.
>
>Do you know in what chemical form is absorbed H3?
>It would interesting to know.
>
>7. To do only experiments is ......an easier and
>softer way in the beginning but later...... it is not
>always ENOUGH to solve the problem.
>You may get to the point: "To MANY numbers and NOT
>ENOUGH explanations".
>
>I am very interested, in ANY info about "Tritium
>Problem", specifically "Tracing" it.
>I would really appreciate if anybody could bring more
>input about Penetration, Tracing, absorption of
>Tritium.
>
>Do we need to discover/design the wheel again?
>
>*** Does anybody have an experience with determining
>the way to connect "Source Sample" to "Sample Point"
>data, other them to do "other isotopes" correlation.
>
>There is a huge experience in Medical Field with
>"Labeling" but it has more of microbiology transfer
>mechanism as major drive-ter.
>
>Chemical Analysis would be the one, but I am not sure
>what to do if there is, basically, something very
>close distillate water? How to trace the water if
>there is almost no impurities?
>
>
>Please, keep me in mind if you have received anything
>via private emails.
>I will keep you updated if I will find out more info.
>
>
>Emil.
>
>
>From: Bharat.Patel@jet.uk (Bharat Patel)
>> Does anyone know of any studies done on the
>>absorption of tritium in
>> various materials, e.g. metals, plastics, rubber,
>>wood, graphite, concrete
>> etc as a function of the exposure concentration and
>>duration of exposure.>
>> I am trying to relate the absorbed level of tritium
>>with its exposure
>> history. For example from studies we have done, we
>>know that for flat
>> sheet metal (aluminium), an exposure of 0.3MBq/m3
>>(8uCi/m3) for several
>> hundred hours results in an absorption less than
>>1Bq/gram in the material,
>> whereas an exposure of 80MBq/m3 for a few hours
>>results in >500Bq/gram.>
>> Is it reasonable to assume a linear relationship
>>between activity in the
>> material and its exposure concentration? What other
>>factors might
>> influence the absorption rate? Incidentally in the
>>above examples, we
>> found no detectable surface contamination after the
>>exposures, whereas the
>> volumetric concentrations were detectable.
>> Any insights into this problem would be appreciated.
>
>>
>> Bharat Patel
>> Health Physicist> JET Facilities> Abingdon> Oxon>
>UK>
>
>
>
>
>
>
>
>
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