Storage cont'd

DOE-HDBK-1132-99

Storage racks and shelves should be constructed of noncombustible

material and designed to hold the storage containers securely in place

and keep them properly separated.

Storage vault doors, racks, and containers should be designed to

accommodate the application of tamper-indicating devices.

Design of the storage vault should facilitate the ease of performing

periodic inventory.

Pyrophoric material should not be stored in a storage vault. Plutonium

metal scraps (e.g., machine turnings, shavings, and fine chips) may be

chemically reactive and should be processed to plutonium oxide before

they are stored in the storage vault. [Because plutonium hydrides,

carbides, oxycarbides, and nitrides are reactive and potentially

pyrophoric, especially in finely divided form (powder), they should be

handled in dry, inert (i.e., oxygen-free) atmosphere and should be

converted to oxides for prolonged storage.]

Plutonium oxide is formed either by the reaction of the plutonium metal

with oxygen in the air or by calcining plutonium compounds, such as the

peroxide, oxalate, and nitrate. Plutonium oxide is generally a chemically

inert powder and insensitive to self-radiation damage. However,

plutonium oxide can absorb moisture from the air (depending on

calcining condition), and incompletely calcined oxide could subsequently

release gases, resulting in over-pressurization (bulging) a storage can. If

the plutonium compounds are not completely oxidized, the subsequent

oxidation process could cause a decrease in the sealed container

pressure, thereby imploding a storage can. To prevent or minimize these

storage problems, plutonium oxides should be stabilized as prescribed

by standards for packaging plutonium for storage.

The use of plastic bags in bag-in/bag-out operations could cause

problems if the heat generated from radioactive decay melts the plastic

bags after prolonged storage. The decomposition of the plastic bags

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