Explosive Stress: Shock, Blast, and Venting

DOE-HDBK-3010-94

4.0 Solids; Powders

The bounding ARFs and RFs for the response of the three categories of powders established

to thermal stress are:

nonreactive compound

6E-3/1E-2

reactive compounds (except fluorides)

1E-2/1E-3

plutonium fluoride

1E-3/1E-3

4.4.2 Explosive Stress: Shock, Blast, and Venting

The effects of shock upon powders of interest in the nuclear industry (dry ceramic oxides,

chemically reactive compounds) are not well defined. Blast effects from both detonations

and deflagrations are assumed to result in the entrainment of powders without substantial

subdivision of the finer fractions (the relaxation time of a particle 10 m in diameter is

3E-4 second and the particle would most probably be entrained rather than fragmented) that

are the primary concern for inhalation. Fragmentation of the coarser fraction with adequate

momentum upon impact or chemical reactions for reactive compounds are possible. The

primary entrainment mechanism is assumed to be the accelerated gas velocity resulting from

the blast effects; that is, the suspension of powders by the impact of air at velocities greater

than those normally associated with aerodynamic entrainment under non-accident conditions

(e.g., suspension by air velocities used for ventilation and exhaust and by ambient outdoor

winds). Two types of aerodynamic entrainment of powders are found: aerodynamic

entrainment from homogenous beds (beds of powder greater than two particle diameters

deep) and aerodynamic entrainment of sparse particles contamination from a heterogeneous

surface (i.e., a hard, unyielding surface). The former is covered here and in section 4.4.4

and the latter is discussed in section 5.3.4.

4.4.2.1

Shock Effects

Gerrard (1963) reported the detection of a velocity component towards the surface from

detonation that appeared to pass through powder on the surface and was reflected by the

surface. If such is the case, it would be anticipated that powder could be suspended by the

reflected wave. The effects of explosion on battlefield dust generation have been reported

(Long, Mason and Durst, September 1984; Strange and Rooke, November 1988). The latter

study was an extensive survey covering some 550 tests involving both uncased (bare) charges

and munitions on or near the surface with TNT equivalent up to 1 x 106 kg but primarily

focused on methods to estimate crater characteristics (Strange and Rooke, November 1988).

Estimates of the mass of soil lofted (dislodged) from the crater averaged 150 kg/(kg TNT

equivalent)0.84 and are reasonably consistent with the amount of soil dislodged in Long,

Mason and Durst (September 1984).

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