In the wake of the demise of the Clinch River Reactor project, ANL scientists developed and promoted the Integral Fast Reactor (IFR) concept. Patterned after the EBR-II with its Integral Fast Reactor fuel cycle facility (see EBR-II discussion), the IFR would integrate the plutonium-breeder reactor with an on-site spent fuel pyroprocessing and electro-refining process. In this process, plutonium and the minor transuranic elements would be separated and recycled together into new fuel.

The IFR was advanced as the key to making the breeder reactor economical, proliferation-resistant and environmentally acceptable.73 There were ample grounds for skepticism, however. Most importantly, pyroprocessing looked still more expensive than conventional reprocessing. Moreover, were the IFR technology to be adopted by a non-weapon state it would provide the country with access to tons of plutonium in each co-located reactor and reprocessing facility. A cadre of experts trained in transuranic chemistry and plutonium metallurgy could separate out the plutonium from the other transuranic elements using hot cells and other facilities on-site. A 1992 study commissioned jointly by the U. S. Departments of Energy and State describes a variety of ways to use a pyroprocessing plant to produce relatively pure plutonium.74

Despite these problems, ANL was able to attract federal support for the IFR concept for a decade until the Clinton Administration cancelled the IFR program and the Congress terminated its funding in 1994. As a political compromise with Congress, it was agreed that while EBR-II would be shut down, funding of the fuel reprocessing research would continue—renaming it the "actinide recycling project."75 A decade later this program would be re-characterized and promoted as necessary for long-term management of nuclear waste—becoming the centerpiece of the George W. Bush Administration’s GNEP.

After Congress terminated funding for the IFR program, the DOE kept its pyroprocessing program alive by selecting it to process 3.35 metric tons of sodium-bonded EBR-II and FFTF spent fuel at INL. In 2006, the DOE estimated that pyroprocessing could treat the remaining 2.65 tons of this fuel in eight years at a cost of $234 million, including waste processing and disposal for a reprocessing cost of approximately $88,000/kg.76