It was thought by the AEC that scaling up components from existing fast reactors (EBR-II was 62.5 MWt and Fermi 1 was 200 MWt) to the size of the proposed CRBR demonstration plant (975 MWt), was too risky technologically to take in one step. Therefore, an intermediate-size reactor, with a mission to test fuels, was inserted into the U. S. LMFBR development program. In July 1967, the U. S. Congress authorized construction of the Fast Flux Test Facility (FFTF), which at that time was estimated to cost $87.5 million and scheduled to begin full-power operation in early 1974.46 The 400 MWt FFTF was a loop-type sodium-cooled, MOX-fueled fast reactor with no blanket for breeding additional plutonium. See figure 7.4.

Construction of the FFTF was completed in 1978 at the U. S. Department of Energy’s (DOE) Hanford, Washington site, and criticality was achieved in 1980. It started serving as a test facility in 1982. When the CRBR was cancelled the following year, the FFTF lost its primary mission but continued to operate until April 1992 to test various aspects of fast reactor design and operation, including experiments designed to verify the ability to passively remove radioactive decay heat from a reactor core via convection of liquid-sodium coolant. By 1993, the usefulness of the reactor was diminishing, so the decision was taken in December of that year to deactivate it. Over the next several years, efforts to find a new mission for FFTF, including producing radioactive isotopes for medical use or tritium for weapons, failed. With its fuel and sodium coolant removed, FFTF continues to be maintained in a cold standby condition, while proponents continue to seek new justifications for its use.