Review of Experimental Studies on Airborne Release From Depleted Uranium

DOE-HDBK-3010-94

4.0 Solids; Metals

different oxidation periods used. The mass of particles 10 m AED and less as a

function of temperature is shown in Figure 4-10 reproduced from the reference

document. The values range from ~ 1E-7 at 500 oC to 8E-6 at 700 oC and 900 oC for

the fraction of the total mass oxidized. Adjusted for the time to completely oxidize

the metal would increase the apparent ARFs to 1E-4 to 4E-2 with RFs from 0.006 to

0.17. The ARF x RFs range from 5E-5 to 4E-3 and are comparable to the values

reported by Carter and Stewart (1970). The authors listed the following conclusions:

Uranium particles in the respirable size range (10 m AED and less)

were made airborne when the rods were exposed to temperature

exceeding 500 oC for time greater than ~ 0.5 hours.

Production of oxide and airborne materials were enhanced by forced-

draft and temperature cycling during oxidation.

Metal rods with the test configuration did not exhibit any tendency

towards self-sustained oxidation, although complete oxidation would no

doubt be achieved if adequate fuel and time (longer than 4 hours) were

provided.

B. R eview of E xp erim en tal S tu d ies on A irb orn e R elease F rom D ep leted U ran iu m

M u n ition s. Jette et al. (August 1989) reviewed the published information available

on the characteristics of the DU particles suspended during testing (firing of kinetic

energy rounds against hard targets, burn tests during hazard classification of rounds

prior to deployment) of the munitions and one study on the characteristics of the

aerosols from the explosive ejection of molten metal droplets. Many studies have

been performed on the DU particles formed by the impact of penetrators against hard

targets (Gilchrist and Nicola, January 1979; Glissmeyer and Mishima, November

1979; Chambers et al., October 1982; Sutter et al., January 1985; Wilsey and

Bloore, May 1989; Parkhurst et al., April 1990; Jette, Mishima and Hadlock, August

1990). Generally, a substantial portion of the mass of DU in the penetrator becomes

airborne by the impact against hard targets (armor) of sufficient thickness to expend

most of the energy of the kinetic round (up to 80%). The size of the airborne

material is very fine with fractions in the 10 m AED and less range of 0.34 to 1.0.

The airborne materials are predominantly U3O8. Up to 50% of the particles in the

respirable fraction may be "D" class (dissolution halftime <10 days).

The other large group of studies providing information on the potential behavior of

uranium under accident conditions are the hazard classification test conducted on

Page 4-40