Le Chatelier' Principle

DOE-HDBK-1132-99

common type of radiolysis-driven reactions should result in the gradual, low-

level build-up of tritiated nitrous and nitric acids on the surfaces of most tritium

contaminated materials. Over the long-term, it should further be expected that

these tritiated nitrous and nitric acids will be broken down into tritiated ammonia

compound dissolved into the surface bound layers of water vapor.

For the most part, this particular type of reaction sequence does not normally

present itself as a problem in day-to-day tritium operations because (1) the

overall production efficiency for these types of reactions is relatively low, and

(2) the materials used for the construction of most tritium-handling systems are

not susceptible to attack by nitrous and/or nitric acids or by tritiated ammonia

compounds. By contrast, however, it should be noted that other types of

radiolysis-driven reactions can expected to occur with tritium in the presence of

compounds containing chlorides and/or fluorides, and these can easily lead to

chloride/fluoride induced stress corrosion cracking. (See, for example, the

discussion on " rganics"in Section 2.10.6, below.)

One additional point that is worth noting about radiolysis-driven reactions is that

their long-term potential for causing damage should not be underestimated.

Although the overall production efficiency for these types of reactions might be

expected to be relatively low, the generation of products from these types of

reactions can, on the other hand, be expected to occur continuously over

relatively long periods of time (i.e., 10-20 years, or more). As a consequence,

the long-term effects from these types of reactions can be difficult to predict,

especially because very little is known about the long-term, synergistic effects

of low-level, tritium micro-chemistry. (See Section 2.10.6.)

Le Chatelier' Principle . A chemical restatement of Newton' Third Law of

Motion, Le Chatelier' Principle states that when a system at equilibrium is

subjected to a perturbation, the response will be such that the system

eliminates the perturbation by establishing a new equilibrium. When applied to

situations like those depicted in Equations (5) and (6), Le Chatelier' Principle

states that, when the background tritium levels are increased in nature (by

atmospheric testing, for example), the reactions will be shifted to the right in

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