Breed plutonium

Breeder reactors were developed to utilize the 97% of natural uranium that occurs as nonfissionable U-238. The idea behind a breeder reactor is to convert U-238 into a fissionable fuel material, plutonium. A reaction to breed plutonium is... 

The Integral Fast Reactor would also be capable of breeding plutonium which could be used as nuclear fuel. This type of reactor was seen as the key to a nuclear future. Liquid sodium is a volatile substance that can burst into flames if it comes into contact with either air or water. An early liquid sodium-cooled breeder reactor, the Fermi I, had a melting accident when 2% of the core melted after a few days of operation. Four years later when the reactor was about to be put into operation again a small liquid sodium explosion occurred in the piping. 

Liquid sodium has attractive properties for its application as a working fluid in a fast neutron reactor with the ability to breed plutonium fuel by the reaction of ura-nium with the fast neutrons. Sodium does not act as a neutron moderator, its liquid state at atmospheric pressure reaches from 97.8 °C to 892 °C, its heat transfer properties are excellent and its nuclear reactions do not cause a long lasting activation. Sodium is the medium which is able to transfer the energy generated in the high density reactor core better than any other heat transfer fluid... 

Fast reactors, through their ability to extend uranium resources by breeding plutonium, require parallel development of fuel cycle facilities. Thus, in the UK, when the decision was made by the UKAEA in 1954 to build the metal-fiielled DFR, it was also decided that dedicated fuel fabrication and reprocessing plants would be located with the reactor at Dounreay. A third frst reactor-oriented fuel plant to make small batches o initially comet, and, later, oxide and carbide fuels for the test programme in DFR, was also built at Dounreay. 

The role of the reactor may be either as a converter, which produces some plutonium by neutron absorption in uranium-238 but depends on uranium-235 for most of the fission, or as a breeder, which contains a large amount of plutonium and produces more fissile material than it consumes. Breeding is also possible using uranium-233 produced by neutron absorption in thorium-232. 

Bose-Einstein Condensate phase of matter that is created just above absolute zero when atoms lose their individual identity Boyle s Law law that states volume of a gas is inversely related to its pressure Breeder Reactor type of nuclear reactor that creates or breeds fissionable plutonium from nonfissionable U-238 Buckministerfullerene Cg, allotrope of carbon consisting of spherical arrangement of carbon, named after architect Buckmin-ister Fuller, Invertor of geodesic dome Buffer a solution that resists a change in pH... 

One of the fascinating features of fission power is the breeding of fission fuel from nonfissionable uranium-238. Breeding occurs when small amounts of fissionable isotopes are mixed with uranium-238 in a reactor. Fission liberates neutrons that convert the relatively abundant nonfissionable uranium-238 to uranium-239, which beta-decays to neptunium-239, which in turn beta-decays to fissionable plutonium-239. So in addition to the abundant energy produced, fission fuel is bred from relatively abundant uranium-238 in the process. 

Plutonium-239. Plutonium-239 represents a fortuitous phenomenon. Whereas U-235 is the only significant fissile nuclide in nature, its major isotope, U-238, captures a neutron to produce another fissile nuclide, plutonium-239. A substantial amount of the energy produced during the life of uranium fuel is produced by the conversion of U-238 to Pu-239 which subsequently fissions. This process provides the basis for the nuclear breeding cycle. 

A similar set of processes has been partially developed for the thorium-uranium system but is not discussed here because it is not expected to be employed in the next several decades. The important feature of the thorium cycle is that it could be used to achieve breeding (to produce more fissionable material than is consumed) in thermal reactors, but nuclear as well as chemical factors have frustrated this development (for more information, see Reference 22). The increasing cost of the natural uranium supply for the ura-nium/plutonium cycle may, several decades in the future, justify development of the thorium cycle. 

Two engineering system demonstrations were performed to reduce the uranium-from-ore requirements of LWRs recycle of the plutonium and conversion to the thorium-uranium cycle to achieve thermal breeding. The demonstration phase of the plutonium recycle development was carried out in seven power reactors. Several LWRs originally were started up on the thorium-uranium cycle, and a light... 

That is the advantage of fission. Its drawback is the deadly radioactivity it generates, particles whose mass, from one type of reactor, is almost equal to the mass of the fuel consumed. Waste from a fission reactor typically requires thousands of years before it breaks down into biologically safe levels. Fission reactors are also relatively inefficient. They can use but a single isotope (atoms of an element that have the same number of protons but a different number of neutrons) of uranium, U-235, which makes up less than 1 percent of natural uranium ore. (More than 99 percent of natural uranium is nonfissionable U-238.) So-called fast breeder reactors might overcome the supply limitation by breeding fissionable fuel from U-238. But the fuel it produces from the uranium is plutonium, the same stuff that was inside the Nagasaki bomb—not an ideal by-product in a politically unstable world. 

On the other hand, liquid metal-cooled fast reactors (LM-FRs), or breeders, have been under development for many years. With breeding capability, fast reactors can extract up to 60 times as much energy from uranium as can thermal reactors. The successful design, construction, and operation of such plants in several countries, notably France and the Russian Federation, has provided more than 200 reactor-years of experience on which to base further improvements. In the future, fast reactors may also be used to burn plutonium and other long-lived transuranic radioisotopes, allowing isolation time for high-level radioactive waste to be reduced. 

In a typical breeder reactor, nuclear fuel containing uranium-235 or plutonium-239 is mixed with uranium-238 so that breeding takes place within the core. For every uranium-235 (or plutonium-239) nucleus undergoing fission, more than one neutron is captured by uranium-238 to generate plutonium-239. Thus, the stockpile of fissionable material can be steadily increased as the starting nuclear fuels are consumed. It takes... 

In thermal reactors fueled with plutonium, the number of neutrons produced per neutron absorbed is less than 2.0 and breeding is impossible. For U, on the other hand, this number is substantially greater than 2.0, and breeding is practicable in a thermal reactor. In fast reactors, the number of neutrons produced per neutron absorbed is close to the total number of neutrons produced per fission, so that breeding is possible with both and plutonium. Breeding as here defined is not possible with U, because there is no naturally occurring isotope from which can be produced. 

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