Depleted uranium is what's left over after enriched uranium is spent at a power plant. It's about 40 percent less radioactive than natural uranium, according to the U. Department of Veterans Affairs. This depleted uranium is only dangerous if it is inhaled, ingested or enters the body in a shooting or explosion. Given its importance in nuclear fuel, researchers are keenly interested in how uranium functions — particularly during a meltdown. Meltdowns occur when the cooling systems around a reactor fail and the heat generated by the fission reactions in the reactor core melts the fuel.
This happened during the nuclear disaster at the Chernobyl nuclear power plant , resulting in a radioactive blob dubbed "the Elephant's foot. Understanding how nuclear fuels act when they melt is crucial for nuclear engineers building containment vessels, said John Parise, a chemist and mineralogist at Stony Brook University and Brookhaven National Laboratory. In November , Parise and colleagues from Argonne National Lab and other institutions published a paper in the journal Science that elucidated the inner workings of melted uranium dioxide, a major component of nuclear fuel, for the first time.
Uranium dioxide doesn't melt until temperatures top 5, F 3, C , so it's hard to measure what happens when the material goes liquid, Parise told Live Science — there's just no container tough enough. The researchers then beam X-rays through the uranium dioxide bubble and measure the scattering of those x-rays with a detector. The angle of scatter reveals the structure of the atoms inside the uranium dioxide.
The researchers found that in solid uranium dioxide, the atoms are arranged like a series of cubes alternating with empty space in a gridlike pattern, with eight atoms of oxygen surrounding each uranium atom. As the material approaches its melting point, the oxygens go "crazy," Argonne National Laboratory researcher Lawrie Skinner said in a video about the results.
The oxygen atoms begin to move around, filling empty space and bopping from one uranium atom to another. Finally, when the material melts, the structure resembles a Salvador Dali painting as the cubes turn into disordered polyhedrals. At this point, Parise said, the number of oxygen atoms around each uranium atom — known as the coordination number — drops from eight to about seven some uranium atoms have six oxygens surrounding them, and some have seven, making for an average of 6.
Knowing this number makes it possible to model how uranium dioxide will act at these high temperatures, Parise said. The next step is to add more complexity. Nuclear cores aren't just uranium dioxide, he said. Uranium is found in small amounts in most rocks, and even in seawater. Historically, conventional mines e. After mining, the ore is crushed in a mill, where water is added to produce a slurry of fine ore particles and other materials.
The slurry is leached with sulfuric acid or an alkaline solution to dissolve the uranium, leaving the remaining rock and other minerals undissolved. However, over half of the world's uranium mines now use a method called in-situ leaching, where the mining is accomplished without any major ground disturbance.
Water injected with oxygen or an alkali, acid or other oxidizing solution is circulated through the uranium ore, extracting the uranium. The uranium solution is then pumped to the surface. Radiation Emergencies. Section Navigation. Facebook Twitter LinkedIn Syndicate.
Radioisotope Brief: Uranium. Minus Related Pages. Where does it come from? What form is it in? What does it look like? About small nuclear reactors power some ships, mostly submarines, but ranging from icebreakers to aircraft carriers. These can stay at sea for long periods without having to make refuelling stops.
In the Russian Arctic where operating conditions are beyond the capability of conventional icebreakers, very powerful nuclear-powered vessels operate year-round, where previously only two months allowed northern access each year.
The heat produced by nuclear reactors can also be used directly rather than for generating electricity. In Sweden, Russia and China, for example, surplus heat is used to heat buildings. Nuclear heat may also be used for a variety of industrial processes such as water desalination.
Nuclear desalination is likely to be a major growth area in the next decade. High-temperature heat from nuclear reactors is likely to be employed in some industrial processes in future, especially for making hydrogen. Both uranium and plutonium were used to make bombs before they became important for making electricity and radioisotopes.
The type of uranium and plutonium for bombs is different from that in a nuclear power plant. Since the s, due to disarmament, a lot of military uranium has become available for electricity production. The military uranium is diluted about with depleted uranium mostly U from the enrichment process before being used in power generation. Over two decades to one-tenth of US electricity was made from Russian weapons uranium.
How Does it Work? What is Uranium? Updated September Uranium is a heavy metal which has been used as an abundant source of concentrated energy for over 60 years.
Uranium occurs in most rocks in concentrations of 2 to 4 parts per million and is as common in the Earth's crust as tin, tungsten and molybdenum. Uranium occurs in seawater, and can be recovered from the oceans. Uranium was discovered in by Martin Klaproth, a German chemist, in the mineral called pitchblende. It was named after the planet Uranus, which had been discovered eight years earlier.
Uranium was apparently formed in supernovae about 6. While it is not common in the solar system, today its slow radioactive decay provides the main source of heat inside the Earth, causing convection and continental drift. The high density of uranium means that it also finds uses in the keels of yachts and as counterweights for aircraft control surfaces, as well as for radiation shielding.
The chemical symbol for uranium is U. The uranium atom On a scale arranged according to the increasing mass of their nuclei, uranium is one of the heaviest of all the naturally-occurring elements hydrogen is the lightest. Inside the reactor Nuclear power stations and fossil-fuelled power stations of similar capacity have many features in common. Uranium and plutonium Whereas the U nucleus is 'fissile', that of U is said to be 'fertile'.
From uranium ore to reactor fuel Uranium ore can be mined by underground or open-cut methods, depending on its depth. A worker holds up a newly made fuel pellet KazAtomProm For reactors which use natural uranium as their fuel and hence which require graphite or heavy water as a moderator the U 3 O 8 concentrate simply needs to be refined and converted directly to uranium dioxide. Who uses nuclear power?
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