Miscellaneous Radiolytic Reactions - doe-std-1128-98

DOE-STD-1128-98

chemistry of plutonium nitrate solutions may be found in Miner and

Seed (1966). In dilute solution (0.1M), GH2 is about 0.5 and GO2

increases to 1.45. Self-reduction of Plutonium hexafluoride as the

solid phase amounts to about 1.5% of the material per day

(Weinstock and Malm, 1956). See Cleveland (1970) Chapter 2, for

more information.

2.5.2.3 Miscellaneous Radiolytic Reactions

A serious limitation to the use of organic ion exchange materials is

their radiation stability. Brookhaven National Laboratory reviewed

the literature and summarized the effect of ionizing radiation on both

organic and inorganic ion exchange materials (Gangwer et al., 1977).

Extraction of plutonium (IV) from 3M HNO3 into 30 vol% tributyl

phosphate in kerosene at 5C decreased the extraction coefficient by

a factor of two when irradiated to a dose of 3.6 x 107 R (Tsujino and

Ishihara, 1966). The mechanical properties of thin plastic films such

as polyethylene and polyvinyl chloride degrade with exposure to

plutonium. Cellulose vacuum-cleaner bags will disintegrate in less

than a month if used for housekeeping purposes in plutonium-

contaminated gloveboxes. Leachability of plutonium-containing

wastes could be affected by the production of nitric acid for air-

equilibrated dilute salt solutions (Rai et al., 1980).

2.5.2.4 Helium Retention and Release

Helium introduced by alpha-bombardment of plutonium and the

alloys and compounds of plutonium can cause lattice expansion. This

was first observed for plutonium oxides, carbides, and nitrides by

Rand et al. (1962) and was later observed for two plutonium carbide

phases. Helium is retained in vitrified compounds. The retention and

release behavior of helium in plasma-torch-fused Pu02 microspheres

for SNAP is an important parameter in the design of the heat source.

Approximately 530 cm3 at standard temperature and pressure (STP)

per year-kg are produced by 238Pu02 (Stark, 1970). Microspheres of

80% 238PuO2and 20% 239PuO2 that were approximately 50 mm in

diameter, prepared by the sol-gel process, released 92.8% of the

helium in 8 months at room temperature (Northrup et al., 1970).

Metals at temperatures well below the melting point trap the

insoluble helium gas in tiny bubbles, which are more or less evenly

distributed through the matrix material (Stevens et al., 1988). Helium

buildup in weapon-grade material is approximately 4 standard cm3

per year-kg.

2.6

OCCUPATIONAL HAZARDS

The major industrial hazard in plutonium facilities is the potential for loss of control

of a highly toxic substance, resulting in either the inhalation or ingestion of

plutonium or one of its compounds by personnel, or the exposure to excessive

radiation from a criticality accident. The possibility of a fire or explosion in a

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