Pressure Seal Failure

DOE-HDBK-3010-94

7.0 Application Examples; Reduction Line Example

Therefore, even if general combustion of all plutonium produced by a completed

reduction reaction is assumed, the overall initial source term estimated is still not

large.

The final aspect of this problem that must be considered is the potential for a

firecracker-type explosion of the initiator. The potential explosion involved is not

large. It would not be expected to exceed a TNT-equivalent of a gram or two. The

mass of inert material includes calcium as well as plutonium, and the crucible wall

would receive a significant portion of the shock impact as well since charges are

placed next to the wall. For the sake of simplicity, however, the plutonium fluoride

powder is assumed to receive the full impact of the explosion. Subsection 4.4.2.1

assessed a combined ARF x RF value of 0.2 x TNT equivalent to be bounding for

powder masses. If the charge is assumed to have a TNT equivalent of 2 g, the initial

respirable plutonium source term would be 0.4 g. If it is assumed that the redundant

charge on the opposite wall of the crucible also ignites, the value would increase to

0.8 g. The overall release to the glovebox atmosphere estimated is small, even using

very conservative assumptions.

B. Pressure Seal Failure. Pressurized venting of a reduction furnace could occur due

to improper gasket installation or a fast buildup of reaction gas byproducts from

excessive moisture in the reduction charge. The venting will occur at elevated

pressures, most likely in excess of 0.34 MPag (50 psig). However, the venting of this

pressure is a phenomenon whose most severe effects are relegated to the vapor space

in the furnace and the immediate surface of the reduction product mixture. The

coalescing molten plutonium at the bottom of the plutonium will not be affected as

significantly as surface material.

The historical experience cited supports the general observation made above. The

incidents reported have not been associated with evidence that a significant portion of

the plutonium mass has been driven airborne. The ARF and RF of 1.0 and 0.5 stated

in subsection 4.2.1.1.5 for "the violent ejection of molten metal and vapor formation

from droplets," or "explosive reaction of the entire metal mass" based on exploding

wire experiments, is objectively inappropriate. Subsection 4.2.1.1.4 specifies an ARF

and RF of 1E-2 and 1.0 for "airborne release of particulates from disturbed molten

metal surfaces (flowing metal, actions resulting in continuous surface renewal), high

turbulence at surface, violent airborne reaction." Even these conditions seem

somewhat excessive for what is expected in the case of the pressure seal failure.

Another important factor to keep in mind is that the experimental conditions from

which the ARF estimate of 1E-2 was obtained involved free fall of plutonium metal

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