UNHand Air-Dried UNH on Various Surfaces During a Shallow Pool Gasoline Fire

DOE-HDBK-3010-94

3.0 Liquids; Organic, Combustible Liquids

3.3.6

U N H an d A ir-D ried U N H on V ariou s S u rfaces D u rin g a S h allow P ool G as olin e

F ire

Experiments were performed by Mishima and Schwendiman (1973) in a wind tunnel to

measure the ARF and RF of uranium from various surfaces (sandy soil, sandy soil with

vegetation cover, stainless steel and asphalt) at windspeeds of 1.0 m/s and 10 m/s.

Windspeed measurements were made at the centerline of the 2-ft x 2-ft wind tunnel and

therefore represent much higher windspeeds (50 mph to 60 mph) at a standard 10-m height.

UNH was placed upon the surface held in a 22-inch diameter flange in the floor of the wind

tunnel. In some experiments with sandy soil, the UNH was allowed to air-dry for several

days prior to testing. One gallon of gasoline was poured over the surface, ignited and the air

drawn over the burning surface. In some cases, the airborne particles were only sampled

during the actual burning; in other cases, the airborne particles were collected for much

longer periods. The ARFs and Rfs measured are reproduced in Table A.3 and the apparatus

shown in Figure A.3 in Appendix A. The relevant data are listed in Table 3-15.

Table 3-15. M easured ARFs and Rfs for Uranium Airborne During Gasoline Fires

on Various Surfaces Involving UNH and Air-Dried UNH

(Table III - M ishim a and Schwendim an, August 1973)

Uranium

Air Velocity,

Rate

Substrate

ARF

Form

m /s

Fraction/hr

Sandy soil

liq. UNH

1.0

1.7E-5

3.0E-6

0.75

4.0E-2*

5.4E-3

0.40

1.0

9.6E-4

0.78

2.0E-4

Vegetation on sandy soil

air-dried UNH

2.0E-3

0.86

4.0E-4

1.0

7.4E-5

0.64

1.0E-5

4.0E-4

0.18

6.0E-5

1.2E-3

0.32

2.0E-4

Asphalt

1.0E-3*

4.1E-4

0.70

1.0

liq. UNH

2.4E-3

0.68

6.0E-3

Stainless steel

1.4E-2

0.40

1.0

6.0E-2

liq. UNH

1.14E-1

0.34

6.0E-1

Calculated based on actual burn time for gasoline fire.

The ARFs range from 1.7E-5 (soil, 1.0 m/s) to 1.14E-1 (stainless steel, 10.0 m/s). The data

are extremely limited with single values at some sets of conditions (surface, windspeed).

The type of surface may have some effect in that the liquid can be absorbed into the substrate

or the substrate can conduct heat. If the substrate conducts heat well, the liquid can be

boiled rapidly generating conditions much more favorable to generation of airborne liquid

droplets. In extreme cases for any surface, a possible mechanism for suspension of liquids

Page 3-48