Since the early 1960s, several countries have undertaken important fast breeder reactor (FBR) development programs. Test reactors were constructed and successfully operated in a number of countries, which includes Rapsodie (France), KNK-II (Germany), FBTR (India), JOYO (Japan), DFR (the United Kingdom), BR-10, BOR-60 (Russian Federation), and EBR-II, Fermi, and FFTF (the United States). This was followed by commercial-size prototypes (Phénix and Superphénix in France, SNR-300 in Germany, Monju in Japan, PFR in the United Kingdom, BN-350 in Kazakhstan, and BN-600 in Russian Federation). However, from the 1980s onward, mostly for economic and political reasons, fast reactor development in general began to decline. By 1994, in the United States, the Clinch River Breeder Reactor (CRBR) had been cancelled, and the two fast reactor test facilities, FFTF and EBR-II, had been shut down. Thus, in the United States, efforts essentially disappeared for FBR development. Similarly, programs in other nations were terminated or substantially reduced. In France, Superphénix was shut down at the end of 1998; SNR-300 in Germany was completed but not taken into operation, and KNK-II was permanently shut down in 1991 (after 17 years of operation) and is now fully dismantled. Apart from this, PFR was shut down in 1994, BN-350 was shut down in 1998, and Phénix was shut down in 2009. One major consequence of the slowdown in fast reactor technology development programs is that considerable knowledge and experience is currently accumulated in the field of decommissioning of reactors and other sodium facilities.