On 22 June 1976, at Energy Secretary Tony Benn’s National Energy Conference, Flowers was more specific about the Commission’s unease about the use of plutonium as a civil fuel. Earlier in June, Benn had told the Commons that the Government would announce in the early autumn its decision about the future of Britain’s fast breeder programme. Work had reached a point at which the Government had to decide:

our approach to the next stage of the system’s development, including our policy on the construction of a fullscale demonstration reactor.

This is a matter of great public importance in terms of long term energy provision and the safety and environmental considerations. In my current review of this I wish to provide the opportunity for wide consultation. I shall take full account of the prospects for international cooperation and the forthcoming report on radiological safety from the Royal Commission on Environmental Pollution.

As it turned out, however, the Royal Commission was concerned about more than just radiological safety. The Commission was deeply apprehensive about the implications of a commitment to what it called the "plutonium economy." This term was coined by Glen Seaborg, a co-discoverer of plutonium, chairman of the U. S. Atomic Energy Commission during most of the 1960s, and an enthusiastic booster of plutonium-breeder reactors. The Royal Commission accepted that there was a case to be made for building a single large fast breeder to assess its safety and social implications. But the Commission went on to warn that "we must view this highly significant first step with misgivings… The strategy that we should prefer to see adopted, purely on environmental grounds, is to delay the development of CFR1" (paragraphs 517-18). After the publication of the Flowers report, on 22 September 1976, the prospect for even a single large fast breeder in Britain became distinctly bleaker.

In September 1977 the Select Committee on Science and Technology published the report of its study into so called "alternative sources of energy." AEA chairman Sir John Hill welcomed the committee’s recommendation that CFR be built. The following month, at a Royal Institution conference cosponsored by nuclear proponents and opponents, Sir Brian Flowers, speaking in the role of a critic in the session on fast breeders, concurred with his co-speaker, the AEA’s Tom Marsham, that one large fast breeder was indeed to be recommended. Nevertheless, despite this apparent closing of ranks within the U. K. nuclear establishment, the Government was less and less eager to give CFR the green light.

Added to this was the view expressed by Sir John Hill, that the AEA did not regard the proposed large fast breeder as in any way an experimental plant. On the contrary, it would just be another nuclear power station, of a new design. Behind this confident assertion lay a crucial corollary: if the new plant was just another power station, it would obviously be paid for not by the AEA but by the electricity suppliers, just as they paid for all their other power stations. However understandably appealing this idea was to the AEA, it did nevertheless come up against a basic problem. The CEGB did not want a fast breeder power station — not, at any rate, if it had to pay for it.

Furthermore, the AEA had by this time undermined its own position, by relabeling its proposed plant. It would be not a Commercial Fast Reactor but a CDFR (Commercial Demonstration Fast Reactor). The internal contradiction in this new label did not go unremarked: surely a plant was either commercial or a demonstration plant? The new designation amounted to an admission by the AEA that the plant would not be in any conventional sense "commercial." It would "demonstrate" the design for a commercial plant; but its electricity output would not be competitive in cost with that from conventional generating plants.

The CEGB let it be known that it would make a site available for a large fast breeder linked to the CEGB system; but it had no intention of putting up the capital for such a plant. The collapse of electricity demand growth was already embarrassing. The CEGB’s excess generating capacity was headache enough as it was, without adding more: especially with the probable aggravation of a novel design. The AEA might get away with pronouncing itself pleased because the PFR’s reactor itself was working properly, despite the deep seated troubles with the steam generators. The CEGB could not take such consolation.

The OPEC oil shock in 1974 had triggered an economic recession throughout the industrialized world. Soaring fuel prices stunned energy users into a new and thriftier awareness of their previous extravagance. Electricity consumption stopped increasing. In some countries like Britain it even decreased. Interest rates in double figures made nuclear power, with its huge capital costs, even less competitive with conventional fuels. The grandiose global vision of an energy future centered on plutonium fueled fast breeders began to look less and less plausible.

From 1978 onwards, official support for introducing the pressurized water reactor (PWR) to succeed the United Kingdom’s gas-cooled graphite-moderated reactors was also tacitly sidelining the fast breeder. Nevertheless the election of the Conservatives under Margaret Thatcher in 1979 noticeably revitalized official support for fast breeders; one of Mrs. Thatcher’s first official visits was to Dounreay, on 6 September 1979. In 1981-82 the focus of nuclear controversy was the battle over the pressurized water reactor at Sizewell B. The fast breeder people kept their heads down.