Small Molten Metal Drops Hurled Through Air or Explosion of Entire Metal Mass

DOE-HDBK-3010-94

4.0 Solids; Metals

Fractional airborne release values of particles 10 m AED or less for these conditions are

reproduced in Table A.23 in Appendix A and are:

Dynamic, Geometric mean

1.9E-3

6E-3

On the basis of the available experimental data, the "median" ARF x RF value is assumed to

be the geometric mean value, 2E-3, reported by Carter and Stewart (1970). The bounding

value is assumed to be the 95% confidence ARF x RF value, 6E-3, reported by Carter and

Stewart rounded upwards to be the same as the comparable value for Pu, 1E-2. Since the

airborne material cooled rapidly after formation and would be comparable to the fine

particulate material from the plastic deformation and rapid oxidation of a thin film of metal

generated during the impact of DU rods against hard targets (armor), the measured value for

this situation, 50% "Y" class + 50% "D" class, is assessed to be bounding.

4.2.1.2.3 S m all M olten M etal D rop s H u rled T h rou gh A ir or E xp losion of E n tire

M etal M ass. "Small molten metal drops" refers to drops with a maximum diameter in the

hundreds of m range. It is also noted that the term "explosion of entire metal mass" refers

to a phenomena internal to the metal matrix itself, not external explosive effects.

Rader and Benson (June 1988) generated molten uranium by the exploding wire technique

and accelerated the molten drops downrange by an electrostatic device. Approximately 36%

of the molten material had been aerosolized by the time the drops had traveled 6-ft and

would probably all aerosolize within the next 10 to 12-ft. The size of the airborne particles

was <1 m AED with a geometric standard deviation of ~ 2. The majority of the airborne

material was in the form of web-like aggregates. Experiments performed in inert gas (argon)

aerosolized orders of magnitude less material although the size distribution/geometric

standard deviation of the airborne material remained unchanged demonstrating the importance

of oxidation to the airborne release phenomena.

On the basis of the available experimentally measured value, the bounding ARF and RF

values for this accident configuration are assessed to be 1.0 and 1.0. As in the previous

subsection, the bounding solubility class for this type of airborne material (rapid cooling of

fine particulate material/fume) is assessed to be 50% "Y" class and 50% "D" class.

4.2.2

E xp losive S tress: S h ock , B last, an d V en tin g

Materials can react explosively from internally generated stress (e.g. rapid heating, chemical

reactions in composite/aggregate materials) or from external stresses. Only shock effects

appear to have the characteristics to result in a significant airborne release from metals.

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