Disturbed Molten Metal Surface With High Turbulence

DOE-HDBK-3010-94

4.0 Solids; Metals

munitions prior to deployment (Gilchrist, Parker and Mishima, March 1978; Hooker et

al., March 1985; Haggard et al., July 1986; Parkhurst et al., March 1990). A pre-

determined number of boxes of munitions are subjected to an intense wood-fuel oil

fire. The distance large fragments (pieces of munitions components and cases,

packing) are ejected and the thermal and blast levels are determined to establish the

exclusion area requirements in the event of accidents in transport and storage. In all

cases, no airborne DU was collected in the air samplers set downwind at various

distances downwind of the fire. Size distributions of the residual oxide powders

(predominantly U3O8) were determined and estimates of the respirable fraction are

based on the presence of particles of 10 m and less AED in the residual oxide. The

size distributions measured show less than 0.01 of the residual oxides are in the

respirable size range. The material in the respirable fraction is much less soluble than

the airborne oxide from impact tests ranging from 96% to 100% in the "Y" class.

From the data reproduced in Figure 4-11 from Carter and Stewart (1970), a geometric

mean ARF x RF of 1E-4 was reported. The 95% confidence level ARF x RF of

4E-4 reported by Carter and Stewart (1970) is exceeded by the ARF and RF estimated

for tests performed by Elder and Tinkle (December 1980), where the gas flow and

temperatures used exceeded those used by Carter and Stewart (1970). Six of nine

ARF x RF values obtained are less than 1E-3, with the greater values at the higher

temperatures (900 oC). The ARF and RF values of 1E-3 and 1.0 are assessed to be

bounding for this thermal stress configuration. The value for the lung solubility class

is assumed to be that determined for the sintered oxides collected from wood-oil fires

involving DU rods in munitions (i.e., >95% "Y" class with the remainder being "D"

class uranium). This value is assessed to be bounding for the issue of lung solubility

class.

4.2.1.2.2 D istu rb ed M olten M etal S u rface W ith H igh T u rb u len ce. Carter and

Stewart performed a series of experiments to measure the characteristics of airborne uranium

from molten metal under static (no metal movement) and dynamic (free-fall drop) conditions.

The experimental apparatus and procedures were covered in subsection 4.2.1.1.4. The size

distributions of the airborne materials are shown in Figure 4-11 reproduced from that

document (the velocity of the updraft through the vertical tube was set at a velocity to carry

particles <30 m AED). The distribution of airborne material from the experiments under

static conditions appears to be a single mode. The airborne material from experiments under

dynamic conditions (2 to 4 m free-fall) are bimodal. The distribution from the experiments

in which "obvious sparking" was observed appears to fit the coarser (upper) curve with the

finer (lower) curve represented by the airborne material under static conditions.

Page 4-42