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Page Title: Reduce the water content to less than 0.5 wt% and similarly reduce equivalent - Continued
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material (e.g., fuels or power grade material) to be packaged under this standard
is relatively pure "product quality" material at PFP.
The mechanism of gas formation from water adsorbed on plutonium oxide and
impurities is highly relevant to both this Standard and to DOE-STD-3013-96. In
both standards, a chemical mechanism described by Stakebake, Haschke et al. in
several peer-reviewed publications is assumed to define the bounding pressure
assumption (hydrogen only, no other gases formed). [Stakebake et al. 1993;
Haschke/Ricketts 1995; Haschke and Martz 1998] The pertinent chemical
reaction is:
PuO2 + x H2O ------> PuO2+x + x H2
As indicated in this equation, decomposition of adsorbed water occurs by a solid
state chemical reaction that generates hydrogen gas and retains oxygen as a
superstoichiometric plutonium oxide. The temperature stability field of this oxide
is not firmly established, but the compound appears to be stable from room
temperature to about 400oC [Morales et al. 1999]. A value of x up to about 0.3,
corresponding to about 2 wt% moisture in plutonium oxide, appears to be
possible in plutonium storage environments [Stakebake et al. 1993;
Haschke/Ricketts 1995; Haschke and Martz 1998].
Recent work by Morales on the rate of the hydrogen/oxygen reaction in
air/hydrogen mixtures over plutonium oxide supports earlier conclusions by
Haschke, et al. that the surface of plutonium oxide, like many other surfaces, is
an effective catalyst for this reaction [Morales 1999; Haschke/Martz 1998].
Accompanying work on hydrogen oxidation in the absence of plutonium oxide
shows that stainless steel and other surfaces readily catalyze this reaction at
temperatures of interest [Quigley 1998]. A recent literature search also shows
conclusively that the H2/O2 reaction is readily initiated by alpha and gamma
radiation [Lloyd et al. 1999 and references contained therein]. Indeed,
remarkably high G values (the yield of product for 100KeV of adsorbed radiation
energy) for recombination (in excess of 100) have been reported, compared to
very much lower G values for liquid or adsorbed water radiolysis (the G value is
near one for liquid water radiolysis) [e.g., see Dautzenberg 1989; Dautzenberg
1990; and Kalashnikov, et al. 1988]. The cited publications conclusively show

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