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DOE-HDBK-3010-94
4.0 Solids; Powders
parameters not readily determined for accident conditions. Estimates of entrainment rates
still require estimates of the duration of the pressure wave/accelerated flow over the deposit
to arrive at estimates for ARFs. Singer, Cook and Grumer (1972) reported entrainment rates
of ~ 10 g/m3 at 5 m/s to ~ 90 g/m  3 at 40 m/s (89 mph) for velocities at the mid-height of the
deposit. Freeman (1972) reported concentrations of 700 to 1100 g/m3 in 1 second at an
explosion equivalent to 1E+8 g TNT but did not indicate if this was entrainment or due to
blast effects.
In the absence of any directly applicable predictive models or release data, other related
experimental values are applied. From the information quoted above, it appears the
entrainment process results from the creation of surface flaws by the detachment of particles
or clumps. Once created, the surface flaws allow more general lifting of the surface until the
entire surface is disrupted. The process requires some period to initiate as shown by the 0.1
to 0.5 seconds necessary to entrain 2 grams from a cohesive surface (Singer, Cook and
Grumer 1972).
Mishima and Schwendiman (August 1973) reported the entrainment of UO2 powder and air-
dried UNH from various surfaces at two air velocities (~ 1.1 and 8.9 m/s 1-ft above the
surface) at ambient temperatures. The experimental apparatus is shown in Figure A.3 and
the experimental results reproduced in Table A.3 in Appendix A. An ARF and RF of
7.6E-2 and 0.14 were measured for the higher of two values for the suspension of UO2
powder from a stainless steel surface for a wind velocity of 8.9 m/s 1-ft above the surface
(comparable to a 22 m/s under normal wind speed measurements) in a 24-hour period. The
velocity of the bulk fluid at distances above the surface may not be a meaningful
measurement and the velocity profile near the surface may be more relevant. In the case of
explosion-generated air velocities, the duration of the peak velocity is in terms of
milliseconds. Approximately 60% of the resuspended powder (4.56E-2) was made airborne
during the first hour of the wind as shown in Figure 4-16 taken from the referenced
document. If resuspension is assumed to be linear over the initial hour the ARF would be
7.6E-4 per minute. It is noted that recent studies indicate resuspension of sparse particle
contamination is not linear, especially at the beginning and end of the suspension period and
that the suspension from the bed of a cohesive material appears to be initiated at surface
imperfections. However, for the flow to be parallel over the surface, the center of the
explosion must be some distance from the deposited material. The entrainment due to the
pressure wave over the surface will be limited as the wave will only be over the deposit for a
short period of time (fractions of a second).
Fry (July 1991) specifically evaluated the effects of a flammable gas detonation outside a
typical glovebox on clump powder sitting on the floor of the glovebox. The simulation used
the HULL hydrocode to model detailed interactions of blast waves loading onto structures
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