Blast Effects

DOE-HDBK-3010-94

3.0 Liquids; Aqueous Solutions

3.2.2.2

B last E ffects

The blast effect of interest is accelerated gas velocities passing over the surface of the liquid.

Mishima and Schwendiman (August 1973) reported the results of measurements of the

airborne release of uranium from various surfaces (soil, vegetated soil, stainless steel, asphalt

with UO2 powder or UNH solution) before, during and after gasoline fires in a wind tunnel

at air velocities of ~1 m/s and ~10 m/s. The flame speed in flammable vapor mixtures is

also on the order of 10 m/s, although flame speed may propagate to sonic velocities under

turbulent conditions. The results are reproduced in Table A.3 and the experimental

apparatus is shown in Figure A.3 in Appendix A. The only experiments involving UNH

solution were performed on a substrate of loose, sandy soil at air velocities of~1 & 10 m/s.

The ARF measured at 10 m/s from soil during a 28-hour sampling period was 3.9E-4 with

an RF of 0.68. The value is comparable to other experiments involving UNH residues from

the fire except for one result from stainless steel at 10 m/s (ARF 2.6E-2 in 6 hours/RF 0.3;

linear rate 4E-3/hr). Therefore, the rapid passage of air at an accelerated velocity from the

deflagration of a flammable vapor mixture does not appear to have the potential to release

large amounts of material from aqueous liquids. The ARF is assessed to be 4E-3/hr for the

time duration of impulse passage over the liquid (generally on the order of 1 second).

3.2.2.3

V en tin g of P ressurized L iq u id s

Liquids, contained in a vessel or containment, can be pressurized by external sources (e.g.,

deflagration in a free volume above the liquid, pressurized gases from an external source) or

by vapor generated by the heating of liquid. If the pressure exceeds the strength of the

vessel/containment, the vessel/containment will fail and, under the proper circumstances, can

release the liquid to the atmosphere as liquid drops.

Droplets of an aqueous solution under pressure can be generated by spray if the pressure is

relieved by venting a cold liquid through a small opening in the wall of the vessel, by the

bubbling action on the surface of the liquid resulting from the release of gases

absorbed/trapped in the cold liquid, and by fragmentation of the liquid by bulk vaporization

when the pressure over a superheated solution is relieved (i.e., flashing spray). The

characteristic of the liquid, the source of the pressure, and the location of the failure all have

an effect on drop formation and release.

Pressure driving the release is estimated by the strength of the external source,

temperature/vapor pressure of the liquid, the temperature/volume expansion of the gases, etc.,

depending on the scenario described. The point of venting is determined by the design,

construction and strength of material of the vessel/containment. If the vent is located below

the level of the liquid, spray formation is the mechanism for drop formation. If the vent is

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