Table 2.6. Solubilities and Properties of Selected Compounds

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

Table 2.6. Solubilities and Properties of Selected Compounds

Measured Solubility

Bulk Density, g Pu/L

Sintered Media

Porosity, :m(a)

Compound

Medium

g Pu/L

Filter Cake

Dry Compound

Fluoride (III)

1M HF - 1M HCl

0.03

1-2.5

15-20

Fluoride (IV)

2M HF - 2M HNO3

0.70

0.6-0.8

0.5-2.0

15-20

0.5M C2O42- - 3M HNO3

Oxalate (III)

0.01

0.6-0.8

15-20

0.1M X2O42- - 4M HNO3

Oxalate (IV)

0.003

0.5-0.6

0.6

15-20

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 PuF4 with 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 acids or molten salts. The

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