What does a breeder reactor produce?

Answer 1

Well, simply put, both are nuclear reactors. A breeder reactor is one which instead of losing it's neutron production to capture in moderators or shielding elements, absorbs most of the neutron production in the fuel specifically for the production of transuranic elements.

Such reactors have been used since the 60's to facilitate in the production of fusion nuclear weapons, also known as hydrogen bombs, as these require large amounts of plutonium which can only be created in a breeder reactor.

The U.N. has been discouraging the use of breeder reactors since the mid nineties and many worldwide have been shut down. This is in part due to their use in the proliferation of nuclear weapons and due to their inherent instability.

There are literally dozens of types of nuclear reactors, breeders being only one. Others include pressurized water reactors, boiling water reactors, graphite moderated reactors, lead cooled reactors, or the more recent pebble bed reactors.

Answer 2

A thermal reactor is one where the fast neutrons arising from fission are moderated or slowed down by a moderator, which can be water, heavy water or graphite. The neutrons become thermalised, that is brought into equilibrium with the temperature of the moderator. This is necessary for the efficient use of U235 which is the fuel used in thermal reactors such as the PWR and BWR. A breeder reactor is a nuclear reactor that generates new fissile or fissionable material at a greater rate than it consumes such material. These reactors were initially (1940s and 1960s) considered appealing due to their superior fuel economy; a normal reactor can consume less than 1% of the natural uranium that begins the fuel cycle, whereas a breeder can utilize a much greater percentage of the initial fissionable material, and with re-processing, can use almost all of the initial fissionable material. Also, breeders can be designed to utilize thorium, which is more abundant than uranium. Renewed interest is also due to the dramatic reduction in waste they can produce and especially long-lived radioactive waste components. Production of fissile material in a reactor occurs by neutron irradiation of fertile material, particularly uranium-238 and thorium-232. In a breeder reactor, these materials are deliberately provided, either in the fuel or in a breeder blanket surrounding the core, or most commonly in both. Production of fissile material takes place to some extent in the fuel of all current commercial nuclear power reactors. Towards the end of its life, a uranium (not MOX, just uranium) PWR fuel element is producing more power from the fissioning of plutonium than from the remaining uranium-235. The plutonium is in effect being bred from the U238 in the fuel.

Historically though, in order to be called a breeder, a reactor must be specifically designed to create more fissile material than it consumes, which is not the case in PWR's or BWR's.

This can be achieved by using thorium which by neutron capture produces U233 which is fissile like U235, so that after the initial fuel load using U235 along with the thorium for breeding, future operation can be sustained by a program of thorium supply alone, together with processing of the irradiated thorium to recover the U233, then using this to continue operation with more thorium for breeding. No reactors of this type have been built commercially, but I believe India has plans to do so. In the US for the present, new reactors will continue to use enriched uranium fuel with no reprocessing. However I believe there is now the intent to build a reprocessing facility which will make breeder reactors a possibility, though I think it will be used to make MOX fuel at first. (MOX means mixed oxide, a mixture of U235 and Pu239 as fissile material. This fuel has been made in the UK and France)

Answer 3

The purpose of a breeder reactor is to produce fissile fuel from non-fissile material. Thus plutonium can be bred from uranium238 which is the most common form of uranium but is not itself fissile. Another route is to breed Uranium 233 from thorium. Of course the breeder reactor would also produce electricity.

Answer 4

Yes, such reactors are possible. The main feature is that a blanket of uranium surrounds the active core, and by absorbing neutrons some of this transmutes to plutonium, which can then be used to make the active core of a further reactor and so on, hence the term 'breeder'. Of course this requires the handling of the irradiated blanket material and chemical separation of the plutonium. This has been done on a trial basis with prototype reactors, in several countries, but nowhere has it been established on a commercial basis, probably because the economics just don't work out favourably at present, with adequate supplies of newly mined uranium available. It could become important in the future.

Answer 5

It is a type of nuclear fission reactor, which once started, can produce it's own fuel for continued operation.

Answer 6

A nuclear reactor where most fission occur at fast neutron energy. It uses no neutron moderator. It produces more nuclear fuel than what is consumed.