Table 2.6. Solubilities and Properties of Selected Compounds

DOE-STD-1128-98

Table 2.6. Solubilities and Properties of Selected Compounds

Measured Solubility

Bulk Density, g Pu/L

Sintered

Media

Compound

Medium

g/PuL

Filter Cake

Dry Compound

Porosity, m(a)

Flouride (III)

1M HF 1M HCl

0.03

1-2.5

15-20

0.70

0.6-0.8

0.5-2.0

15-20

Fluoride (IV)

2M HF 2M HNO3

0.5M C2O42- - 3M HNO3

0.01

0.6-0.8

15-20

Oxalate (III)

0.1M C2O42- - 4M HNO3

0.003

0.5-0.6

0.6

15-20

Oxalate (IV)

Peroxide (IV)

3M H2O2 - 1M HNO3

0.10

0.10-0.6

30-80

(a) Sintered media porosity required to remain precipitate.

Plutonium hexafluoride is the only volatile plutonium compound (bp 62C)

and is marginally stable. It can be prepared by oxidizing PuF4with F2 at an

elevated temperature (Weinstock and Malm, 1956). It can also be prepared at

low temperatures by a fluorinating agent, fluorine dioxide (Malm et al.,

1984). Plutonium waste treatment and decontamination may benefit from

processes using photolysis or microwave discharge to produce active fluorine

species from FOOF or CF4/O2 mixtures, which will react with plutonium or

plutonium dioxide to form PuF6(Martz et al., 1991).

2.3.3.2 Plutonium Dioxide

Plutonium dioxide may now be the most important and most

thoroughly studied of all plutonium compounds. Due to its chemical

stability and relative inertness, it is the preferred form for shipping

and storing plutonium at the present time. Direct oxide reduction

(DOR) of PuO2 is part of the integrated pyrochemical system used at

the Los Alamos National Laboratory (LANL) (Christensen and

Mullins, 1983; Mullins et al., 1982). Plutonium dioxide is formed

when plutonium or its compounds (except the phosphates) are

ignited in air, and often results when oxygen-containing compounds

are heated in vacuo or in an inert atmosphere to 1000C (Cleveland,

1970). The properties of PuO2 are reported by Moseley and Wing

(1965).

Loose PuO2 powder, as formed by calcination, usually has a density

of about 2 g/cm3. If the oxide is pressed and sintered into pellets, it

may have a density of about 10.3 to 11.0 g/cm3. Surface

measurements of typical oxides prepared from the calcination of

plutonium (IV) oxalate at various temperatures range from 10 to 60

m2/g. Caldwell (1961) found that the surface area decreased with

increasing temperatures. Plutonium oxide fired at temperatures

>600C is difficult to rapidly or completely dissolve in common

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