Modeling the Behavior of Tritium

DOE-HDBK-1132-99

order to adjust to the new equilibrium conditions by readjusting to the naturally

occurring isotopic ratios. Thus, we get reactions of the type

CH4 + 2T2 W CT4 + 2H2 ,

(5a)

W 2HTO + H

and

2H2O + T2

(6a)

The inverse situation also applies in that, when the background tritium levels

are decreased in nature, the reactions will be shifted back to the left, by again

readjusting to the naturally occurring isotopic ratios; i.e.,

W CT

CH4 + 2T2

+ 2H2 ,

(5)

W 2HTO + H

and

2H2O + T2

(6)

By itself, Le Chatelier' Principle is a very powerful tool. When applied

singularly, or to a sequential set of reactions like those depicted in Equations

(5), (5a), and (5) again, and/or (6), (6a), and (6) again, Le Chatelier' Principle

shows that exchange reactions of the types depicted above tend to behave as

springs, constantly flexing back-and-forth, constantly readjusting to changing

energy requirements, in a constantly changing attempt to establish a new set of

equilibrium conditions.

Since elemental hydrogen, regardless of its form (H 2, D2, T2, and all

combinations thereof), can be expected to dissolve to some extent in virtually

all materials, Le Chatelier' Principle can be expected to work equally as well

on solubility reactions, like those shown above in the generic Equations (4a),

(4b), and (4c). These will be covered in more detail under the heading of Bulk

Contamination Modeling (see below).

Modeling the Behavior of Tritium . Any model of the behavior of tritium starts

2.10.6

with the assumption that all three hydrogen isotopes coexist in nature, in

equilibrium with each other, in the nominal isotopic ratios described above in

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