Prototype Cathode Processor (PCP)

The Prototype Cathode Processor (PCP) is a high-temperature vacuum furnace capable of retorting volatile components of the charge material and producing a consolidated ingot (used primarily for research on spent nuclear fuel processing).

The Prototype Cathode Processor (PCP) is a facility that provides a high-temperature vacuum furnace for research in processing spent reactor fuel. The PCP can retort (distill) volatile components of the charge material and can also produce a consolidated ingot of high-melting metallic components. It has recently undergone a capacity upgrade, giving it the following capabilities:

• Maximum charge size: 22 liters
• Maximum furnace temperature: 1600°C
• Pressure range: vacuum (< 0.1 torr) to atmospheric
• Process atmosphere: high-purity argon
• Induction heating power: 30 kW

The PCP is a bottom-loading furnace design, with the hot furnace region situated above the cool condenser region. The main furnace components (induction coil and susceptor) do not move during loading/unloading. But the crucible assembly (see Figure 1) is lowered and raised by dedicated mechanisms for convenient access to both the process crucible on the top and the receiver crucible on the bottom.
Most operations with the PCP, from loading/unloading to complex process cycles, are computer-controlled. This assures safe, reliable operation with a minimum of operator interaction. Extensive instrumentation monitors process temperatures and pressures, as well as status of various functions and positions of valves, motors and other mechanical components.

Figure 1. Crucible assembly of the Prototype Cathode Processor. Click on image to view larger image.

The PCP is enclosed in a large glove-box located in the High-Bay of Building 308. This glove-box provides personnel protection from the hazardous and radioactive process materials. It also allows a protective argon atmosphere to be maintained around the furnace. This is important in preventing oxidation of the equipment and ignition of pyrophoric materials, and to properly simulate the hot-cell environment at Idaho National Laboratory.

The original purpose of the PCP was to support development and testing in an identical unit in the Fuel Cycle Facility at Idaho National Laboratory. This unit, the Cathode Processor, was designed to purify the metal/salt mixture produced by the electrorefiner. The electrorefiner is the main component of the pyrometallurgical treatment process developed at Argonne to reprocess spent metallic nuclear fuel.

Testing in the PCP has played an important role in optimizing process parameters and in developing suitable materials for crucibles and crucible coatings for the cathode processor. Among the notable achievements of the PCP are the processing of the following materials:

• 33 kg of cadmium
• 74 kg of uranium and salt
• 22 kg of eutectic salt

Figure 2. The cathode processor: a large-scale high-temperature retort for processing metals under vacuum or pressure conditions. Click on image to view larger image.

The PCP has conducted a wide range of experiments, focusing primarily on studies of crucible materials and coatings. The uranium process metal, in conjunction with the electrorefiner salt that is present, poses a difficult challenge for crucible materials at the high process temperatures. Graphite, ceramics, and several novel composite materials are being explored.

The versatility of the PCP has allowed it to perform tests that were not originally planned. Numerous tests in support of the metal waste form furnace have been conducted at temperatures as high as 1600°C. This is well beyond the original design temperature of 1370°C. And the retort aspect of the cathode processor has allowed the prototype unit to purify, by distillation, several hundred kilograms of uranium chloride salt produced by the Chemical Sciences and Engineering Division of Argonne.

An overall view of the PCP is shown in Figure 2.

Last Modified: Mon, September 13, 2010 7:47 PM