Plutonium breeder fuel

The technologically most important isotope, Pu, has been produced in large quantities since 1944 from natural or partially enriched uranium in production reactors. This isotope is characterized by a high fission reaction cross section and is useful for fission weapons, as trigger for thermonuclear weapons, and as fuel for breeder reactors. A large future source of plutonium may be from fast-neutron breeder reactors. 

Uses of Plutonium. The fissile isotope Pu had its first use in fission weapons, beginning with the Trinity test at Alamogordo, New Mexico, on July 16, 1945, followed soon thereafter by the "Litde Boy" bomb dropped on Nagasaki on August 9, 1945. Its weapons use was extended as triggers for thermonuclear weapons. This isotope is produced in and consumed as fuel in breeder reactors. The short-Hved isotope Tu has been used in radioisotope electrical generators in unmanned space sateUites, lunar and interplanetary spaceships, heart pacemakers, and (as Tu—Be alloy) neutron sources (23). 

Plutonium breeder LMFBR fuels, 6, 926 Plutonium carbide nuclear fuels, 6, 928 Plutonium complexes, 3,1131-1215 cupferron, 2, 510 Plutonium(III) complexes... 

While the goal of bringing plutonium production and consumption into balance is a long term one, research and development on proliferation-resistant fuel cycles should be taking place at present. International cooperation ofthe appropriate countries in this R D is also essential. Failure to pursue a suitable R D effort and international cooperation is virtually certain to result in the adoption ofthe most proliferation-prone fuel cycle when the plutonium breeder is deployed in the next century. 

The amount of U-235 present in a nuclear fuel rod is gradually depleted, and ultimately there is insufficient present for the economic generation of power. A fast-breeder reactor uses the interaction of U-238 with energetic (fast) neutrons to generate the plutonium isotope Pu-239. As Pu-239 can be used as a nuclear fuel, a breeder reactor produces more fuel than it consumes. The sequence of steps is ... 

This reaction occurs in reactors designed specifically to produce fissionable fuel. These reactors are frequently called breeder reactors because they produce more fissionable fuel than is used in the reaction. Plutonium is also produced in thermal reactors that contain Plutonium can be obtained through the processing of spent fuel elements. To be useful as a fuel, plutonium must be alloyed to be in a stable phase as a metal or a ceramic. 

The breeder reactor, which would produce and bum plutonium and gradually increase the inventory of fissionable material, requires reprocessing of nuclear fuel. As of 1995 only limited research and development was in progress on breeder reactors, mainly in France and Japan. 

The recycle weapons fuel cycle rehes on the reservoir of SWUs and yellow cake equivalents represented by the fissile materials in decommissioned nuclear weapons. This variation impacts the prereactor portion of the fuel cycle. The post-reactor portion can be either classical or throwaway. Because the avadabihty of weapons-grade fissile material for use as an energy source is a relatively recent phenomenon, it has not been fully implemented. As of early 1995 the United States had purchased highly enriched uranium from Russia, and France had initiated a modification and expansion of the breeder program to use plutonium as the primary fuel (3). AH U.S. reactor manufacturers were working on designs to use weapons-grade plutonium as fuel. 

In plutonium-fueled breeder power reactors, more plutonium is produced than is consumed (see Nuclearreactors, reactor types). Thus the utilisa tion of plutonium as a nuclear energy or weapon source is especially attractive to countries that do not have uranium-enrichment faciUties. The cost of a chemical reprocessing plant for plutonium production is much less than that of a uranium-235 enrichment plant (see Uranium and uranium compounds). Since the end of the Cold War, the potential surplus of Pu metal recovered from the dismantling of nuclear weapons has presented a large risk from a security standpoint. 

Nuclear fission power plants were at one time thought to be the answer to diminishing fossil fuels. Although the enriched uranium fuel was also limited, an advanced nuclear reactor called breeders would be able to produce more radioactive fuel, in the form of plutonium, than consumed. This would make plutonium fuel renewable. Although plutonium has been called one of the most toxic elements known, it is similar to other radioactive materials and requires careful handling since it can remain radioactive for thousands of years. 

In fast (neutron) reactors, the fission chain reaction is sustained by fast neutrons, unlike in thermal reactors. Thus, fast reactors require fuel that is relatively rich in fissile material highly enriched uranium (> 20%) or plutonium. As fast neutrons are desired, there is also the need to eliminate neutron moderators hence, certain liquid metals, such as sodium, are used for cooling instead of water. Fast reactors more deliberately use the 238U as well as the fissile 235U isotope used in most reactors. If designed to produce more plutonium than they consume, they are called fast-breeder reactors if they are net consumers of plutonium, they are called burners . 

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