This was discovered in the earliest nuclear reactors built by the American Manhattan Project for plutonium production.

Two earlier reactors were constructed at Beloyarsk: an AMB-100 reactor (operational 1964-1983) and an AMB-200 reactor (operational 1967-1989).

He helped design an early large reactor in West Milton, N.Y., and the Seawolf, the nuclear submarine.

The N.R.C. granted it within six months, compared with the more than two years that earlier reactors took to achieve that transition.

One of the smallest, earliest reactors was cut apart by remote-controlled plasma torches mounted on a tripod above the vessel.

By the time the experiments were completed, Teller had lost interest, however the results were then applied to improve the earlier reactors.

Liquid metal coolants have included sodium, NaK, lead, lead-bismuth eutectic, and in early reactors, mercury.

The new designs confront several other chronic problems of earlier nuclear reactors.

Ten of these early reactors are still in operation.

The earliest Soviet reactor failure occurred on July 4, 1961, and involved Russia's first nuclear-powered missile-carrying submarine, which was on its maiden voyage.