In the last quarter of the 20th century the development of fast reactors declined. Nuclear power in general was set back, partly because of the Chernobyl accident, so that the fear that supplies of uranium would run out receded and with it the perception that breeding was neces­sary, at least for many decades. In addition, in the West in particular the public mood turned away from nuclear power and also in many countries from large government-funded development projects. The world’s largest fast reactor power station, Super-Phenix, was built in France but suffered a series of setbacks so that it lost political sup­port and was shut down prematurely. In the UK PFR struggled with a series of technical problems, and there was a sodium fire at Monju in Japan. A European collaboration succeeded in designing a “next — generation” fast reactor EFR (the European Fast Reactor) but there was no interest in constructing it. In the United States the development of oxide-fuelled reactors came to an almost complete halt. Only BN — 600 in the Soviet Union and then Russia was conspicuously successful as a reliable power station.

Amid these setbacks, however, there were several signs of poten­tial for the future. A widespread concern about the disposal of nuclear waste gave rise to interest in the use of fast reactors to consume, or “incinerate”, hazardous radionuclides. A concern about safety led to the suggestion that subcritical reactors driven by particle accelerat­ors would be less prone to damaging reactivity accidents. Experience of sodium fires led to reexamination of alternative coolants such as helium or lead. The latter was given impetus by the release of inform­ation about the Soviet submarines powered by small lead-cooled fast reactors that had been developed, unknown to the rest of the world, in the 1970s. In the United States development of metal fuel contin­ued in the 1980s and early 1990s. EBR-II was used to demonstrate burnup of nearly 20%, and this, coupled with work on pyro-chemical reprocessing of the fuel, led to a proposal for an “integral fast reactor” (IFR) system.

Throughout this period information was exchanged under the aegis of the International Atomic Energy Agency. The IWGFR (Interna­tional Working Group on Fast Reactors) was established in 1967, held regular technical discussion meetings and issued several reports including a series of “Status Reports” on fast reactor development worldwide.