In 1975 the U. S. Government Accountability Office (GAO) estimated that the "AEC’s total LMFBR program funding through fiscal years 1948-74 was approximately $1.8 billion."42 GAO gave the LMFBR Program costs for fiscal year 1975 as $481 million,43 which, in 2006 dollars would be approximately $1.6 billion (figure 7.3). The commercialization effort featured two components, a base program R&D effort focused on two test reactors, and a demonstration plant effort, the CRBR.

Southwest Experimental Fast Oxide Reactor

All early fast breeder concepts were based on metallic fuel. In the 1960s, however, work was begun on the use of ceramic, mixed plutonium-oxide/uranium-oxide (MOX) fuel. The Southwest Experimental Fast Oxide Reactor (SEFOR) was a 20 MWt sodium-cooled MOX-fueled fast-neutron reactor designed to determine the operating characteristics of a reactor with MOX fuel, and, in particular, to examine the implications of the Doppler thermal feedback coefficient associated with the use of MOX.44 SEFOR did not produce electricity.

Located near Strickler, Arkansas, SEFOR was built and operated for the AEC by General Electric Company under the Southeast Atomic Energy Associates, a nonprofit consortium formed by 17 power companies and European nuclear agencies including the Gesellschaft fur Kernforschung of Karlsruhe, West Germany.

Experiments at SEFOR confirmed that the negative temperature coefficient of reactivity associated with the use of mixed-oxide fuels would improve the safety of fast reactors under accident conditions involving increases in the fuel temperature.

SEFOR began operating in May 1969, and was shut down three years later. The fuel and irradiated sodium coolant were removed and taken offsite later in 1972, and some dismantling performed. The reactor was acquired by the University of Arkansas in 1975 and is still owned by the university, although the university has never operated it.45