How is pu 239 produced in a uranium fission reactor

Plutonium combines with oxygen, carbon, and fluorine to form compounds which are used in the nuclear industry, either directly or as intermediates. Table 4 shows some important plutonium compounds.

Plutonium metal is insoluble in nitric acid and plutonium is slightly soluble in hot, concentrated nitric acid. However, when plutonium dioxide and uranium dioxide form a solid mixture, as in spent fuel from nuclear reactors, then the solubility of plutonium dioxide in nitric acid is enhanced due to the fact that uranium dioxide is soluble in nitric acid.

This property is used when reprocessing irradiated nuclear fuels. The subsequent absorption of a neutron by plutonium results in the formation of plutonium Absorption of another neutron by plutonium yields plutonium The higher isotopes are formed in the same way. Since plutonium is the first in a string of plutonium isotopes created from uranium in a reactor, the longer a sample of uranium is irradiated, the greater the percentage of heavier isotopes.

Plutonium must be chemically separated from the fission products and remaining uranium in the irradiated reactor fuel. This chemical separation is called reprocessing. It is important to remember that this classification of plutonium according to grades is somewhat arbitrary. The ability of countries to build nuclear arsenals from reactor grade plutonium is not just a theoretical construct.

It is a proven fact. All grades of plutonium can be used as weapons of radiological warfare which involve weapons that disperse radioactivity without a nuclear explosion. Posted on July, Last modified April, Download this page as a PDF.

Table 1. C Boiling point: deg. Since each beta decay turns a neutron into a proton, these two beta decays suffice to turn a uranium atom into one of plutonium. Thus, a single U atom absorbing a single neutron and being allowed to sit long enough to undergo two beta decays a few weeks or so will turn into a single atom of Pu Making heavier plutonium nuclides is just as easy — when Pu captures additional neutrons it turns into Pu, Pu, Pu, and more.

Not only is it fairly easy, but it happens all the time in any operating nuclear reactor. Making the lighter nuclide is a little more roundabout. Remember that, through neutron capture, a reactor produces Pu Otherwise, the reactor is called a "sub-generator. The conditions for regeneration are very far from being met for conventional reactors of nuclear power plants that use slow neutrons. However, significant quantities of plutonium are generated in their irradiated fuel.

This amount was growing by 70 tons per year. EN FR. One is nearly twice the density of lead The alpha phase is hard and brittle, like cast iron, and if finely divided it spontaneously ignites in air to form PuO 2.

Beta, gamma and delta phases are all less dense. Alloyed with gallium, plutonium becomes more workable. Russia has maintained a positive policy of civil plutonium utilization. Apart from its formation in today's nuclear reactors, plutonium was formed by the operation of naturally-occurring nuclear reactors in uranium deposits at Oklo in what is now west Africa, some two billion years ago.

Civil plutonium stored over several years becomes contaminated with the Pu decay product americium see page on The Many Uses of Nuclear Technology , which interferes with normal fuel fabrication procedures.

After long storage, Am must be removed before the plutonium can be used in a MOX fuel fabrication plant because it emits intense gamma radiation in the course of its alpha decay to Np The European Space Agency is paying NNL to produce Am for watt e radioisotope thermoelectric generators RTGs using very pure Am recovered from old civil plutonium, as the isotope is much less expensive than Pu now scarce.

Of some 2, types of radioisotopes known to humankind, only 22 are capable of powering a deep-space probe, according to a study by the US National Academy of Sciences. Of these, all but Pu are problematical due to being too expensive, emitting too much radiation to work with, or lacking enough heat output however, note European use of Am in above section on Plutonium and americium.

The decay heat of Pu 0. These spacecraft have operated for over 35 years and are expected to send back signals powered by their RTGs through to The Cassini spacecraft carried three generators with 33 kg of plutonium oxide providing watts power as it orbited around Saturn, having taken seven years to get there. See also information page on Nuclear Reactors and Radioisotopes for Space.

Plutonium is made by irradiating neptunium, recovered from research reactor fuel or special targets, in research reactors. Np is formed and quickly decays to Pu Pu was then recovered by further reprocessing at the H Canyon plant there. This was essentially Cold War-origin material. Currently, supplies of high-purity Pu are scarce.

Since the early s after production ceased at Savannah River in , the USA was buying all its supply for spacecraft from Russia — some INL supplies the neptunium and does some of the irradiation. It uses the High Flux Isotope Reactor, irradiating neptunium targets for 72 days. The plutonium is then chemically separated and purified to produce an oxide powder.

ORNL expects production to ramp up to 1. OPG would use a similar process to that at its Pickering units to produce cobalt These would be irradiated at Darlington then returned to Chalk River for processing. Production target is reportedly 5 kg Pu per year by about , but the project is yet to receive regulatory approval. Early heart pacemakers used Pu as the power source, and after 30 years some were still running well. It takes about 10 kilograms of nearly pure Pu to make a bomb though the Nagasaki bomb in used less.

Producing this requires 30 megawatt-years of reactor operation, with frequent fuel changes and reprocessing of the 'hot' fuel. Allowing the fuel to stay longer in the reactor increases the concentration of the higher isotopes of plutonium, in particular the Pu isotope, as can be seen in the Table above.

For weapons use, Pu is considered a serious contaminant, due to higher neutron emission and higher heat production. It is not feasible to separate Pu from Pu The operational requirements of power reactors and plutonium production reactors are quite different, and so therefore is their design.