Miscellaneous Radiolytic Reactions - STD-1128-98master0050

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

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% 238PuO2 and

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

2-24