Release Estimation cont'd

DOE-HDBK-3010-94

7.0 Application Examples; Dry Processing Line Example

the calciner just fills the 10 storage positions, which are then emptied in a continuous

run of the calciner. Plutonium nitrate solution could be accumulated with plutonium

quantities up to ~ 1 kg by the end of a complete calciner operating cycle.

Approximately 2500 g of plutonium as plutonium oxide and fluoride can physically be

in the hydrofluorinator at any one time. No special storage rack is provided in the

hydrofluorination glovebox. By procedure, two containers holding ~ 2300 g of

plutonium fluoride product (i.e., ~ 1800 g as Pu) apiece are allowed in the glovebox.

There is no need to provide long-term storage because the button reduction furnaces

operate as batch units, unlike the calciner that is fed continuously from an

accumulated source of feed; and it is the hydrofluorinator, not the reduction

operation, that is the "chokepoint" in the process flow. Hydrogen fluoride MAR is

not specifically examined in this example, because it is a gas (ARF = 1), and the

fundamental focus of these examples is radionuclide releases.

A large room fire where the room contains a glovebox with plutonium powders has

already been examined for the feed preparation operation in section 7.3.1. In that

example, the predominant release effect was heating of plutonium powders, for which

the ARF and RF were 6E-3 and 0.01 (subsection 4.4.1.1). The ARF and RF values

for heating of plutonium fluoride powders assessed to be bounding in subsection

4.4.1.1 are 1E-3 and 0.001. If the plutonium feed storage for the calciner were

considered to experience this release mechanism, the total release would be:

(23,000 g * 1.0 * 6E-3 * 0.01) + (3600 g * 1.0 * 1E-3 * 1E-3) = 1.4 g

Unfortunately, this model may seriously underestimate potential airborne releases

because the powder is stored in light plastic jugs (i.e., non-hardened plastic). These

jugs will pyrolyze quickly and burn provided the fire is of a minimum duration and

heat generation rate. Intermingling of material with melting, bubbling, and burning

plastic introduces more release stresses and mechanisms than simple heating of

powders.

Polystyrene is reasonably representative of the type of plastics used in molded plastic

containers. Subsection 5.2.1.4 assessed bounding ARF and RF values to be 1E-2 and

1.0 for powder contamination on burning polystyrene. The principal question is,

therefore, how much of the material in the plastic jugs might experience this release

mechanism? If sufficient powder is accumulated, it is conceivable that not all of the

material would experience the effects associated with burning plastic. A large amount

of powder may remain as a coherent mass as the plastic "disintegrates" around it.

Another factor to consider is the geometry of storage. If the plastic jugs are elevated

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