Reduction Line - h3010v20193

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

Calcium and pyrotechnic charges are brought into the line via an airlock on the back wall of

the glovebox. In-line storage of these materials is prohibited, and only the quantities needed

for a given charge are brought into the glovebox. The weight of the calcium charge is

reverified, and then the plutonium fluoride, calcium, and two pyrotechnic initiators are

loaded into a magnesium oxide crucible. The initiators reduce the ignition temperature

required for commencing the reduction reaction, thus reducing the ultimate reduction

pressure.

The crucible is then moved to the loading station, where it is placed inside a stainless steel

reduction vessel packed with sand. The reduction vessel is mechanically a simple steel can

of sufficient dimensions to withstand an internal pressure of 700 psig at 3100 F. It serves

as the pressure vessel for the reduction reaction, while the inner magnesium oxide crucible

prevents intermetallic reactions that would ruin the product from occurring between molten

plutonium and the walls of the can. After loading, the pressure vessel is covered with a

stainless steel lid that will be sealed to the reduction furnace head by a copper gasket

designed to fit machined grooves on the lid.

The reduction vessel is then placed in the recessed portion of the hydraulic piston face.

There are two pistons in the line, one for each furnace. They lift the reduction vessel up and

seal it against the top of the furnace shell. Each furnace is a cylindrical stainless steel vessel

with interior water-cooled induction coils, with power supplied by a common 30-kW, 10-kHz

motor generator set. The piston raises the pressure vessel until it is inside the induction coils

and seals the furnace with approximately 24,000 pounds total force. Interlocks prevent

energizing the heating coils and deenergize them if the hydraulic pressure is at any value

below its normal full rating or if the piston is not raised to its full stroke height.

The reduction furnace is evacuated by one of two small vacuum pumps, and the chamber is

then pressurized to 5 psig with argon. An opening is provided in the furnace head for a

manifold inlet that allows evacuating and inerting the furnace. Inerting is required because

oxygen in the furnace would cause plutonium oxide formation, thus reducing product yield.

Argon is used instead of nitrogen for the same reason, with plutonium nitride being the

contaminant of concern.

The reduction process begins with a gradual heating of the pressure vessel. At a temperature

in the range of 60 C to 150 C the pyrotechnic initiator will fire and the highly exothermic

reduction reaction will commence, as noted by a sharp increase in temperature indication on

the outer wall of the pressure vessel. Temperatures within the pressure vessel will rise to

levels sufficient to melt the reaction products and ensure that the calcium/fluoride residue

slags will remain molten long enough to allow the elemental plutonium to coalesce in the

bottom of the pressure vessel. The control system has a timing unit that will secure heat to

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