Search results
Results from the WOW.Com Content Network
The BN-350 fast-neutron reactor at Aktau, Kazakhstan.It operated between 1973 and 1994. A fast-neutron reactor (FNR) or fast-spectrum reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons (carrying energies above 1 MeV, on average), as opposed to slow thermal neutrons used in thermal-neutron reactors.
The integral fast reactor (IFR), originally the advanced liquid-metal reactor (ALMR), is a design for a nuclear reactor using fast neutrons and no neutron moderator (a "fast" reactor). IFRs can breed more fuel and are distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.
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.
The projected increase in uranium price did not materialize, but if uranium demand increases in the future, then there may be renewed interest in fast reactors. The GFR base design is a fast reactor, but in other ways similar to a high temperature gas-cooled reactor. It differs from the HTGR design in that the core has a higher fissile fuel ...
Fast breeder reactors do not use moderators, since they run on fast neutrons, but the coolant (often lead or sodium) may serve as a neutron absorber and reflector. For this reason they have a positive void coefficient. Magnox reactors, advanced gas-cooled reactors and pebble bed reactors are gas-cooled and so void coefficients are not an issue ...
For "thermal" (slow-neutron) fission reactors, the typical prompt neutron lifetime is on the order of 10 −4 seconds, and for fast fission reactors, the prompt neutron lifetime is on the order of 10 −7 seconds. [16] These extremely short lifetimes mean that in 1 second, 10,000 to 10,000,000 neutron lifetimes can pass.
Reactors that use lead or lead-bismuth eutectic can be designed in a large range of power ratings. The Soviet union was able to operate the Alfa-class submarines with a lead-bismuth cooled intermediate-spectrum reactor moderated with beryllium from the 1960s to 1998, which had approximately 30 MW of mechanical output for 155 MW thermal power (see below).
Pool type sodium-cooled fast reactor (SFR) A sodium-cooled fast reactor is a fast neutron reactor cooled by liquid sodium.. The initials SFR in particular refer to two Generation IV reactor proposals, one based on existing liquid metal cooled reactor (LMFR) technology using mixed oxide fuel (MOX), and one based on the metal-fueled integral fast reactor.