Overview - h3010v20168

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

placed in a chainveyor for transfer to the drying line. Filtrate from precipitation still

contains recoverable quantities of plutonium in solution, so it is transferred to the filtrate

evaporator in the evaporation line. There the volume is reduced by a factor of approximately

10 and residual peroxide is broken down from the heat. The recoverable bottoms are

transferred back to dissolver tanks #1 through #6 for recovery, and the distillate again goes

to waste tanks #17 through #19.

The dry line consists of three separate operations in series gloveboxes similar in arrangement

to the dissolver lines. These operations are calcination, hydrofluorination, and HF

scrubbing. The calcining glovebox has temporary storage capability for peroxide cake.

Individual batches are first manually placed into a drying oven that provides an initial low

temperature drying cycle. The peroxide cake is then manually dumped into the calciner

hopper where the unit screw feeder moves it into the calciner.

Air exiting the calciner often has significant quantities of entrained plutonium even after

passing through a separator due to the flaky nature of the peroxide cake and various design

difficulties with the air flowpath in the calciner. Therefore, the calciner exhaust is passed

through a nitric acid scrubber that dissolves entrained plutonium. The liquid used in the

scrubber normally contains recoverable quantities of plutonium by the time a calcination

cycle is complete and is transferred to dissolver tanks #1 - #6 for recovery.

The calcining tube and its associated screw feeder extend through the calcining glovebox wall

and into the hydrofluorination line. At the end of the screw feeder, there is a machined

paddle wheel which scoops the calcined plutonium oxide to a dropoff into a small vessel.

The paddle wheel has been machined so as to maintain a physical isolation barrier between

the calciner and the hydrofluorinator. The feed vessel serves as a hopper for the

hydrofluorinator screw feeder. Plutonium oxide is reacted to plutonium fluoride in the

hydrofluorinator and is collected in cans at the opposite end of the unit. The plutonium

fluoride is sent by conveyor to the metal reduction line.

The hydrofluorinator is designed to use excess HF, which must be scrubbed before it is

exhausted from the building. The HF scrubber line accomplishes this with potassium

hydroxide in a venturi scrubber. The liquid from this scrubber normally has only waste

concentrations of plutonium and is transferred to tanks #20 and #21 for eventual disposal as

liquid waste.

The reduction line is an inerted glovebox where plutonium fluoride is mixed in a magnesium

oxide crucible with calcium metal and a pyrotechnic initiator. The crucible is then sealed in

a pressure vessel and hydraulically locked into a reduction furnace. The reduction furnace

heats the mixture, and the firing of the pyrotechnic initiator commences the reduction

Page B-24