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. An explosive device could be made from plutonium extracted from low burn-up reactor fuel i.
Typical 'reactor-grade' plutonium recovered from reprocessing used power reactor fuel has about one-third non-fissile isotopes mainly Pu d. In the UK, the Magnox reactors were designed for the dual use of generating commercial electricity as well as being able to produce plutonium for the country's defence programme. A report released by the UK's Ministry of Defence MoD says that both the Calder Hall and the Chapelcross power stations, which started up in and respectively, were operated on this basis 3.
The government confirmed in April that production of plutonium for defence purposes had ceased in the s at these two stations, which are both now permanently shutdown. The other UK Magnox reactors were civil stations subject to full international safeguards. International safeguards arrangements applied to traded uranium extend to the plutonium arising from it, ensuring constant audits even of reactor-grade material.
This addresses uncertainty as to the weapons proliferation potential of reactor-grade plutonium. The 'direct use' definition applies also to plutonium which has been incorporated into commercial MOX fuel, which as such certainly could not be made to explode.
As can be discerned from the attributes of each, it is the first which produces weapons-usable material. Total world generation of reactor-grade plutonium in spent fuel is some 70 tonnes per year. About one-third of the separated Pu has been used in mixed oxide MOX fuel.
The UK's plutonium stockpile is tonnes of separated civil plutonium from historic and current operations and foreign swaps. At the end of France had about 75 tonnes of separated civil plutonium stored domestically.
Some Japan at the end of had about 9 tonnes of separated civil plutonium stored domestically, plus The USA had no reactor-grade plutonium separated, but had at the end of about 45 tonnes of weapons-grade material destined for MOX. China at the end of had about 41 tonnes of separated civil plutonium. Plutonium is a silvery-gray metal that becomes yellowish when exposed to air.
Most plutonium in the environment is in the form of microscopic particles that are the remnants of nuclear weapons testing and nuclear reactor accidents. Because it emits alpha particles, plutonium is most dangerous when inhaled.
When plutonium particles are inhaled, they lodge in the lung tissue. The alpha particles can kill lung cells, which causes scarring of the lungs, leading to further lung disease and cancer. Plutonium can enter the blood stream from the lungs and travel to the kidneys, meaning that the blood and the kidneys will be exposed to alpha particles.
Once plutonium circulates through the body, it concentrates in the bones, liver, and spleen, exposing these organs to alpha particles. Plutonium that is ingested from contaminated food or water does not pose a serious threat to humans because the stomach does not absorb plutonium easily and so it passes out of the body in the feces. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Plutonium fission provide about one third of the energy produced in conventional reactors.
It is not necessary to extract this plutonium which is produced in the nuclear fuelbecause. The U. Atomic weapon tests have dispersed up to s about 10 tons of plutonium into the atmosphere. The level of fallout on the ground is between 10 and picocurie per kilogram 0. Accidents and releases nearby weapon tests facilities have caused locally more important contaminations. Plutonium occurs most commonly in the form of highly insoluble oxide. It remains in the first centimeters of the ground surface.
In water, plutonium is found in the upper layer of sediment to which it strongly adheres. Typically, only one part out of is dissolved. In soil, chemical or biological processes can make soluble a small fraction of plutonium. But while plutonium may be accumulated in aquatic organisms, there is no accumulation in the food chain. The Cassini mission's environmental impact statement determined that a solar powered spacecraft would require a total array area of more than square meters.
Arrays this size would have been too large and heavy for Cassini's launch vehicle—at that time the biggest and most powerful rocket available.
A plutonium fuel pellet, glowing with the heat it produces. Credit: U. Department of Energy.
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