Powders - h3010v10097

DOE-HDBK-3010-94

4.0 Solids; Summary

P ow d ers

For low-energy stresses, powders do not tend to significantly fragment. For high-energy

stresses considered in this document, the size fraction of powders of concern have relaxation

times on the order of fractions of a millisecond, and thus do not tend to present themselves

for fragmentation. Therefore, the amount of respirable material assumed airborne using this

handbook should not exceed the amount of respirable material originally present in the source

MAR, if that value is known. If the value is not known, and the bounding value specifically

uses as the RF the fraction of original MAR less than 10 m AED, an RF of 0.1 can be

assumed based on Ayer, et al. ( May 1988).

T h erm al S tres s

The ARFs and RFs assessed to be bounding for various plutonium compounds subjected to

thermal stress (temperature <1000 oC, natural convection) are given below. For the

chemically non-reactive compounds in powder form, suspension is from the entrainment of

pre-formed particles by the flow upwards from the heated surface. The mass of particles in

any size range (respirable size) released cannot exceed the total mass of particles in the

source powder since no new particles are formed. For the reactive compounds in powder

form, the release is dependent on the particles formed by the reaction (oxidation in the

experiments presented) and the phenomena that would carry the particles formed into the

local flow field. Thus, some variation is anticipated.

Bounding

(non-reactive compounds)

ARF 6E-3/RF 1E-2

(reactive compounds except PuF4)

ARF 1E-2/RF 1E-3

(PuF4)

ARF 1E-3/RF 1E-3

E xp losive S tres s

The effect most closely resembling stresses in a given explosive-type accident scenario is

chosen. There is no need to assume cumulative releases for all effects cited.

Shock effects. Based upon data for cratering and associated airborne release

of soil a respirable release of the mass of inert material equal to 20% of the

calculated TNT equivalent is assessed to be bounding for detonations in or

contiguous to powder in open air where shock and blast effects will quickly

disperse. The mass of the material-of-concern is dependent upon the

concentration of the material-of-concern in the powder.

Page 4-7