Plutonium Nitrate, Oxalate, Peroxide, and Fluorides

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

(plutonium oxalate) are insoluble in water. The chlorides, nitrates, perchlorates, and

sulfates are soluble in water. Plutonium (IV) ions complex readily with organic and

inorganic compounds.

Of particular importance for radiological safety considerations are the solubility, particle

size, and surface area of plutonium compounds. These properties play an important part

in the transportability of plutonium in the environment and in the body. All plutonium

compounds, except the oxides, are assumed in ICRP 30, Part 1 (ICRP, 1979) to behave as

class W compounds in the ICRP lung model. Plutonium oxides are assumed to be

class Y. The solubility of plutonium compounds is an important parameter in avoiding

"unintentional" homogeneous reactors. Knowledge of this property for both aqueous and

organic solvents plays a key role in criticality safety and deserves a high priority.

Unfortunately, little data on particle-size are available, and those that have been

generated focus on the reactivity of the materials in the separation and conversion

processes. Much of the data are reported as crystallite size, which relates to surface area

and solubility but not necessarily to the way the particles would be dispersed in the air.

Surface area plays a role in the ability of materials to adsorb gases and vapors that can

affect the long-term storage behavior of plutonium compounds. Pressure buildup in

storage containers, either from out gassing due to self-heating or radiolytic effects, will

depend on the stability of the compound and the amounts of chemisorbed or physisorbed

water or other substances.

The following sections discuss the essential compounds of plutonium: plutonium nitrate

and associated compounds, plutonium dioxide, plutonium hydride, plutonium sulfate,

plutonium chlorides, and plutonium fuel mixtures.

2.3.3.1 Plutonium Nitrate, Oxalate, Peroxide, and Fluorides

Plutonium (IV) nitrate is the most used of all plutonium compounds. Essentially

all chemical processing of plutonium has been conducted in nitrate solutions.

These solutions of appropriate acidities range from concentrations of 10g to 250g

of Pu/L for efficient precipitation processes. Intermediate compounds are also

used in the processing of plutonium prepared from the nitrate: plutonium (III)

fluoride, plutonium (II or IV) oxalate, and plutonium peroxide. Plutonium (IV)

fluoride can be prepared from any of the preceding solids by hydrofluorination.

Plutonium fluoride has been the compound of choice for reduction to the metal

with calcium, principally because it is nonhygroscopic. The solubilities in

various media, bulk densities, and particle sizes of these compounds are given in

Table 2.6.

2-13