Eluate Evaporation

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

After loading, the resin is washed with 35% nitric acid to remove impurities absorbed

on the resin. This wash cycle is directed to the effluent storage tanks as well. The

columns are then eluted (downflow) with 4% nitric acid, which produces a purified

plutonium nitrate solution that is directed to eluate tanks #7 and #8 in the tank farm.

The final portion of the cycle consists of providing a reconditioning flow of 35% nitric

acid through the columns. These cycles are also conducted at approximately 120 F to

shorten cycle time. All of the flow alignments associated with this cycle are

conducted by operator repositioning of manual valves. Temperature sensors on the

columns or on the outlet of the heat exchanger provide an alarm at 128 F and will

shut the air-operated steam inlet valve if temperatures reach 135 F. Vent lines are

also provided on the ion exchange columns, which go to the vessel vent system.

Temperature, flow, and pressure indications for the system are provided locally and in

the facility control room. The sump level interlock stops major chemical addition to

the glovebox as in all liquid processing gloveboxes.

2.2.2.5.2

E lu ate E vap oration

It is necessary to evaporate a portion of the eluate solution to provide peroxide

precipitation feed concentrated enough for efficient product formation. This is

accomplished in the evaporation line, which has two virtually identical evaporation

systems. One is used for evaporation of ion exchange eluate, and the second is used

for evaporation of precipitation filtrate. A simple schematic of the eluate evaporation

system is provided as Figure B.10.

The evaporator unit itself is constructed of steel mesh reinforced Pyrex and consists

of three critically safe cylinders joined by critically safe tubes. The system draws

solution to the center, or evaporator portion of the unit, by gravity flow from a small

slab head tank mounted in the overhead of the glovebox. This head tank is filled

from eluate storage tanks #7 and #8 via a gear pump in the glovebox. Sloping lines

lead to a reboiler that is heated by process steam in sheathed heating coils. Bottoms

are drawn off to provide precipitation feed via a manually set throttle valve. A

condenser cooled by chilled water is used to liquify the distillate from the unit, which

is then pumped to tank farm vessels #17 through #19. Bottoms leaving the evaporator

are driven by gravity and evaporator pressure through a cartridge filter and a chilled

water heat exchanger to one of two pencil tanks in the glovebox. These tanks are

critically safe because bottoms concentration cannot be known exactly, and the

potential for excessive concentration exists. The bottoms are sampled via a small in-

glovebox sampling line to verify plutonium concentration before pumping to tank farm

vessels #13 and #14.

Page B-38