The use of these bombs has been extremely controversial since their detonation, as they killed hundreds of thousands of people. This destructive use of nuclear power has probably affected how people have viewed the rare few nuclear disasters in Chernobyl , Fukushima , and Three Mile Island.
Overall, this has left a very negative view of nuclear energy in a large portion of the general population. The video below is from the University of Nottingham's periodic videos project. Fossil Fuels. Nuclear Fuels. Acid Rain. Climate Change. Climate Feedback. Ocean Acidification. Rising Sea Level. June 17, The fuel elements are surrounded by a substance called a moderator to slow the speed of the emitted neutrons and thus enable the chain reaction to continue.
Water, graphite and heavy water are used as moderators in different types of reactor. Because of the kind of fuel used i.
A typical megawatt MWe reactor can provide enough electricity for a modern city of up to one million people. Whereas the U nucleus is 'fissile', that of U is said to be 'fertile'. This means that it can capture one of the neutrons which are flying about in the core of the reactor and become indirectly plutonium, which is fissile.
Pu is very much like U, in that it fissions when hit by a neutron and this yields a similar amount of energy. Because there is so much U in a reactor core most of the fuel , these reactions occur frequently, and in fact about one-third of the fuel's energy yield comes from 'burning' Pu But sometimes a Pu atom simply captures a neutron without splitting, and it becomes Pu Because the Pu is either progressively 'burned' or becomes Pu, the longer the fuel stays in the reactor the more Pu is in it.
The significance of this is that when the spent fuel is removed after about three years, the plutonium in it is not suitable for making weapons but can be recycled as fuel. Uranium ore can be mined by underground or open-cut methods, depending on its depth. After mining, the ore is crushed and ground up. Then it is treated with acid to dissolve the uranium, which is recovered from solution. Uranium may also be mined by in situ leaching ISL , where it is dissolved from a porous underground ore body in situ and pumped to the surface.
This is the form in which uranium is sold. Before it can be used in a reactor for electricity generation, however, it must undergo a series of processes to produce a useable fuel. For most of the world's reactors, the next step in making the fuel is to convert the uranium oxide into a gas, uranium hexafluoride UF 6 , which enables it to be enriched.
Enrichment increases the proportion of the uranium isotope from its natural level of 0. This enables greater technical efficiency in reactor design and operation, particularly in larger reactors, and allows the use of ordinary water as a moderator. After enrichment, the UF 6 gas is converted to uranium dioxide UO 2 which is formed into fuel pellets.
These fuel pellets are placed inside thin metal tubes, known as fuel rods, which are assembled in bundles to become the fuel elements or assemblies for the core of the reactor. In a typical large power reactor there might be 51, fuel rods with over 18 million pellets. 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.
When the uranium fuel has been in the reactor for about three years, the used fuel is removed, stored, and then either reprocessed or disposed of underground see Nuclear Fuel Cycle or Radioactive Waste Management.
This amounts to over TWh each year, as much as from all sources of electricity worldwide in It comes from about nuclear reactors with a total output capacity of about , megawatts MWe operating in 32 countries. About 50 more reactors are under construction and about are planned. Over the 60 years that the world has enjoyed the benefits of cleanly-generated electricity from nuclear power, there have been over 18, reactor-years of operational experience.
See also Nuclear Generation by Country. Recent data form Russia indicate that the figure may be lower, at about metric tons rounded. A cut-away view of the Japanese "Monju" fast breeder reactor.
The two circuits contain sodium coolant with the secondary, non-radioactive loop drawing heat from the primary loop. The December, sodium leak occurred in the secondary circuit. The size of the plutonium core in the bomb that exploded over Nagasaki would fit easily into an adult's hand.
The current amount of separated commercial plutonium is enough to make 20, to 30, crude but highly effective nuclear weapons. Seaborg left revealed that an isotope of neptunium decayed to yet another transuranium man-made element. In February, Seaborg identified this as element 94, which he later named plutonium. By May, he had proven that plutonium was 1.
This finding made the Fermi-Szilard experiment more important than ever, as it suggested the possibility of producing large amounts of the fissionable plutonium in a uranium pile using plentiful uranium, and then separating it chemically. Surely this would be less expensive and simpler than building isotope-separation plants.
A second, perhaps easier, path to the atomic bomb now seemed possible. Previous Next.
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