Reduction Line cont'd

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

the furnace if the reduction reaction does not begin within a set time period. The same

control circuit will initiate another timing cycle that will not allow lowering of the piston and

retrieval of the pressure vessel until a 6-hour cooling period has been completed.

After the reduction reaction has occurred, the induction coils are deenergized and a small

argon purge is initiated while the furnace cools for 3 hours. The piston is then lowered,

dropping the pressure vessel out of the reduction furnace. The pressure vessel is removed,

undisturbed, and placed in one of six recessed wells, where it is allowed to cool for an

additional 4 hours. At the end of this time, the pressure vessel is placed in a dumper. This

simple mechanical device merely inverts the chamber, dumping the plutonium button, and the

sand, slag, and crucible onto a stainless steel pan. At this point, the maximum temperature

of the material should be no more than 100 F.

A hammer is used if necessary to break up the crucible, and the finished button is moved to

the pickling station. This station and the remaining equipment, though structurally part of

the same glovebox, are separated from the rest of the reduction line by an airlock. The

button is moved through this airlock and dipped in a small (2 liters) bath of 35% nitric acid

to dissolve any slag adhering to the button. The acid is then washed off the button by

immersion in an identical water bath.

The button then moves to the sampling station where a 3/8" drill is used to obtain a small

turning sample for analysis. The sample is placed in a small glass vial and transported to the

H-7 analytical lab. The button moves on to a weighing station, where it is independently

weighed twice. The weight of the button is recorded and assigned a tracking number on the

accountability computer. Then it is placed in a steel can that is crimp-sealed. The steel can

is bagged out of the glovebox and sealed by an electrically heated portable bag sealer. The

complete package is then sealed inside a second steel can.

Historically, this unit has experienced failure of the furnace pressure seal on four occasions

in the early to mid-1970's. In two of these instances, small fireballs travelling the length of

the glovebox were observed as the inerting system was not routinely used at that time. In

these cases, minor damage to glovebox gloves occurred and contamination was released to

the operating room. However, there was no indication of major plutonium losses from the

reduction crucible. The cause of the multiple pressure seal failures was traced to improper

gasket design or use and, on one occasion, bypassing of piston interlocks. The last instance

in 1976 involved reuse of a deformed gasket. No such incidents have occurred since the

concluding investigation in 1976, which also resulted in the decision to use pyrotechnic

initiators to reduce ultimate reduction pressure.

Page B-50