The standard accepts two approaches to verification that materials have been

DOE-STD-3013-2004

approved by DOE. The procedure of technical equivalency has allowed the DOE to

incorporate new technical basis information into the stabilization process without

continuous modification of the Standard. Although not suggested in this Standard,

one perceived benefit of calcining plutonium oxide is reducing the respirable fraction

of the powder [USDOE 1994a]. Haschke and Ricketts reported particle size

distributions for plutonium oxide prepared from oxalate precipitation and hydride-

catalyzed oxidation of metal after a calcination cycle that included treatment at

950C for two hours [Haschke/Ricketts 1995]. The authors' measurements indicated

that about 2% of the mass fraction for hydride-derived oxide was below ten microns

in size, compared to about 0.05% for oxalate derived oxide, implying that the

method of oxide preparation can be a strong determinant of the particle size

distribution. This work also indicated that the frequently assumed correlation of

specific surface area with particle size is not always valid, due to porosity effects. In

other words, the decrease in surface area observed in calcination is not necessarily

accompanied by a decrease in the number of smaller particles. Subsequent work by

Machuron-Mandard and Madic [Machuron-Mandard/Madic 1996] examined particle

size behavior for oxalate-derived plutonium oxide calcined at 100C intervals

between 450C and 1050C. The studies showed that the number of very small

particles increases as the oxide is calcined at temperatures above 750C, while the

oxides fired at lower temperature are made up of medium size grains. This work thus

indicates that for oxalate derived plutonium oxide, the number density of respirable

particles may actually increase for calcination temperatures above 750C.

2. The standard accepts two approaches to verification that materials have been

adequately stabilized: 1) testing essentially every container loading (each container

would have a moisture measurement applicable to it, even if the measurement was

of a batch sufficient to fill several containers) or 2) use of a "qualified process" for

stabilization and packaging that would reduce the requirements for materials testing.

1) Stabilization at 950C and appropriate handling prior to packaging ensure that

the only significant mechanism for container pressurization is decomposition of

readsorbed water into hydrogen gas. Thus, verification of adequate stabilization

requires only measurement to ensure that residual moisture in the packaged

material is below the threshold specified in Criterion 6.1.2.3.