Table 8.3. Interim Recommendations for Storage of Plutonium Metal and Plutonium Oxide - Continued

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Table 8.3 (cont'd)

Hydride-catalyzed oxidation is suspected. Such reaction is indicated by a mass increase

in either of two circumstances:

For packages whose masses continue to increase since initial packaging or for

which historical mass data are unavailable (see item 6 above), a mass increase

greater than 15 g per kilogram of plutonium over a one-year period indicates a

hydride-catalyzed oxidation reaction.(a)

ii)

For a package whose mass has remained constant over a period of several years

(less than 0.5 g change) from its reference value, then undergoes an annual mass

increase of more than 2 g per kilogram of plutonium, hydride-catalyzed reaction is

indicated. Such a package is particularly suspect. The indications are that a

previously sealed container may now be breached and that the continuing reaction

may lead to rapid containment failure within 12 to 24 months

The measured package mass, relative to the reference mass, corresponds to the mass that

indicates formation of oxide with a volume exceeding 10% of the free volume of the inner

vessel. Each 1-g increase in mass corresponds to formation of 1.5 cm3 of oxide with a

density of 50% of the theoretical value of 11.46 g/cm3.

Inspected containers exhibiting abnormalities (e.g., external contamination, bulging,

discoloration, or other anomalies) should be repackaged in accordance with well-defined

procedures (see items 3 and 4 above). Handling such containers outside of a glove box or

conveyor confinement requires respiratory protection until the package is placed in an overpack

container (e.g., taped metal can or sealed plastic bag) before further handling and transport.

As an interim measure, material that is repackaged may be placed in a food pack can or slip-fit

(Vollrath) container with a secured lid. If possible, metal should be repackaged in a

configuration containing at least one gas-tight seal. No plastic material should be in direct

contact with plutonium metal or oxide, and use of plastic in outer layers of packaging should be

minimized.

When packaging metal, hazardous or pyrophoric material such as plutonium hydride should be

removed. However, it is not necessary to remove protective oxide film. Metal should be

packaged in as dry and inert an environment as possible to minimize corrosion (<100 ppm H20).

8-22