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

DOE-HDBK-3010-94

4.0 Solids; Metals

The authors concluded that 1) total airborne release was unaffected by the presence of

sodium (the ARFs measured for the two experiments in which only Pu was present were well

within the range of ARFs for the remaining experiments), 2) the fraction of airborne particles

in the <11 m AED fraction was higher when Na was present (0.28 to 0.98 vice 0.27 and

0.40), and 3) the fraction <3.7 m AED is also higher. The fact that the presence of Na

did not result in greater total airborne releases with the procedures used (Pu-Na heated in

argon with air suddenly introduced at temperature) is surprising in that the reaction as

described appears to be very energetic. Perhaps the fact that the Na surrounded the Pu and

reacted first may have limited oxygen availability and thus the Pu oxidation rate. Thus, Pu

oxide may not have been generated until after the greater part of the turbulence from the

sodium reaction was terminated. The ARF measured for the experiment in which Pu was

only heated resulted was in the range for the other experiments but the RF was low (0.12).

Review of the data does not indicate any specific cause to which the wide variability in the

data can be attributed.

The ARFs measured range from 3.6E-7 to 6.5E-3. The maximum ARF measured was

6.5E-3, which is in the range of ARFs reported by Eidson and Kanapilly (February 1983)

and Stewart (1963) of 1E-2. The median ARF measured is 7E-6 with an average of 5E-4.

The ARFs for the 2 experiments involving only Pu were 9.6E-6 and 4.4E-5 with an average

value of ~ 3E-5. The RFs are 0.27 and 0.41 with an average of 0.34. The average RF for

the 5 experiments involving Pu with sodium was 0.76; twice as high as for Pu only. Since

the value exceeds the measured values for 5 experiments, the reported ARFs may be an

order of magnitude less.

The data from Eidson and Kanapilly (February 1983) and Eidson, Yeh and Kanapilly (1988)

were included in this configuration primarily because the intent was to determine airborne

release under more severe accident conditions and other atmospheres. With a few exceptions

(5 ARFs ranging from 1.1E-3 to 5.2E-3) the results would be bounded by the ARF and RF

values assessed as bounding for airborne release during self-sustained oxidation. These

results are for specimen weights ~ 1 gram or less and in some cases (heating in hydrogen

and argon atmospheres) would appear to represent ARFs for hydrides. However, the Carter

and Stewart data and other studies bound these results. Accordingly, bounding ARF and RF

values are assessed to be 1E-2 and 1.0.

4.2.1.1.5 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. The term "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.

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