The Integral Fast Reactor (IFR) program comprises all the research, development and demonstration activities needed to produce a revolutionary new nuclear reactor and fuel cycle technology. Selection of the materials with the optimum physical properties for the reactor fuel and coolant allows construction of a simpler, more reliable nuclear power plant and an economic closed fuel cycle. Successful demonstration of the technology will mean that the most significant technical problems facing nuclear power today can be essentially eliminated as a new generation of advanced nuclear fuel systems supplements the 30 year old technology in place today.

Reactor fuel assemblies are composed of individual elements consisting of fuel rods sealed inside cladding tubes. These can be left in a reactor producing power for a few years, but not indefinitely. With IFR metal alloy fuel, 10-20% of the nuclear fuel actually fissions to produce power before cladding material (stainless steel) limits are reached and fuel must be removed for recycling (compared to 3-6% for current reactors). The function of the IFR fuel cycle to recover the fuel that is unused, form new fuel rods and place them into new cladding, then return this fuel to the reactor until essentially all of it is used to produce energy.

The IFR program is developing a particular simple fuel recycle technology called the pyroprocess, so named because the three key steps are conducted at relatively high temperatures. These steps are electrorefining, used to separate the useful fuel materials from the radioactive fission products; cathode processing, which further purifies the metal product of electrorefining; and injection casting, which is a technology widely used to form metals and plastics into desired shapes and is used in the IFR to form new fuel rods.

Electrorefining is a chemical process that uses an electric current to drive the chemical reactions. In the electrorefiner, electricity is used to dissolve the metal fuel in molten salt and then to drive chemical reactions that separate the uranium, plutonium, and transuranics from the fission products. This process has several advantages over other reprocessing schemes. One key advantage is that transuranium elements such as americium, neptunium, etc. are not separated from uranium and plutonium. Therefore they automatically return to the reactor, where in the IFR, they fission to produce power, rather than become troublesome waste. The fission products, which do become low-volume waste, are a concern for only a few hundred years, compared to a 1000 times that long for spent fuel from current generation reactors. This could greatly ease the burden on the geologic repository.

Cathode processing separates the resultant electrorefining process fluids (i.e., salt and cadmium) from the uranium and plutonium product. This process uses high temperatures to boil the cadmium and salt while the uranium and plutonium are consolidated into metal ingots. The salt and cadmium are condensed, collected and recycled back into the electrorefiner.

The ingots from the cathode processor are combined with zirconium in an injection casting furnace. The casting furnace melts the metals and injects the alloys into molds. After cooling, the metal alloy is removed from molds, inspected, and reassembled into new fuel elements which are then bundled into fuel assemblies and transferred to the reactor.

This fuel cycle differs from traditional recycling methods because the fuel materials are always highly radioactive, making diversion for unlawful purposes extremely difficult. Also, the required equipment is smaller and simpler, which enables the recycling plant to be economical at a smaller scale. Therefore if desired, the fuel cycle facility may be an integral part of the reactor plant and shipment of nuclear materials can be significantly reduced.

An existing facility at Argonne National Laboratory in Idaho has been modified to demonstrate these key features of the IFR fuel cycle process. The equipment will be similar in size to a commercial-sized plant. However, only the amount of fuel needed to support EBR-II and demonstrate its commercial potential will be processed during the demonstration. When eventually EBR-II is decommissioned, the equipment will be used to process all the EBR-II fuel prior to disposal.

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