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A fission fragment reactor is a nuclear reactor that generates electricity by decelerating an ion beam of fission byproducts instead of using nuclear reactions to generate heat. By doing so, it bypasses the Carnot cycle and can achieve efficiencies of up to 90% instead of 40–45% attainable by efficient turbine-driven thermal reactors.
This is an annotated list of all the nuclear fission-based nuclear research reactors in the world, sorted by country, with operational status. Some "research" reactors were built for the purpose of producing material for nuclear weapons.
The mere fact that an assembly is supercritical does not guarantee that it contains any free neutrons at all. At least one neutron is required to "strike" a chain reaction, and if the spontaneous fission rate is sufficiently low it may take a long time (in 235 U reactors, as long as many minutes) before a chance neutron encounter starts a chain reaction even if the reactor is supercritical.
Modern nuclear reactor designs have had numerous safety improvements since the first-generation nuclear reactors. A nuclear power plant cannot explode like a nuclear weapon because the fuel for uranium reactors is not enriched enough, and nuclear weapons require precision explosives to force fuel into a small enough volume to become supercritical.
A fission nuclear power plant is generally composed of: a nuclear reactor, in which the nuclear reactions generating heat take place; a cooling system, which removes the heat from inside the reactor; a steam turbine, which transforms the heat into mechanical energy; an electric generator, which transforms the mechanical energy into electrical ...
Nuclear power plants operate between these two points of reactivity, while above the prompt critical point is the domain of nuclear weapons, pulsed reactors designs such as TRIGA research reactors and the pulsed nuclear thermal rocket, and some nuclear power accidents, such as the 1961 US SL-1 accident and 1986 Soviet Chernobyl disaster.
The first major accident at a nuclear reactor occurred at the 3 MW SL-1, a U.S. Army experimental nuclear power reactor at the National Reactor Testing Station, Idaho National Laboratory. It was derived from the Borax Boiling water reactor (BWR) design and it first achieved operational criticality and connection to the grid in 1958. For reasons ...
The CROCUS research reactor of the École polytechnique fédérale de Lausanne, in Switzerland. Research reactors are nuclear fission-based nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime ...