Nuclear fission plutonium

Scientists later discovered a third isotope, plutonium-239, also could undergo nuclear fission. Plutonium-239 does not occur in nature but can be made synthetically in nuclear reactors and particle accelerators. 

Approximately 25—30% of a reactor s fuel is removed and replaced during plaimed refueling outages, which normally occur every 12 to 18 months. Spent fuel is highly radioactive because it contains by-products from nuclear fission created during reactor operation. A characteristic of these radioactive materials is that they gradually decay, losing their radioactive properties at a set rate. Each radioactive component has a different rate of decay known as its half-life, which is the time it takes for a material to lose half of its radioactivity. The radioactive components in spent nuclear fuel include cobalt-60 (5-yr half-Hfe), cesium-137 (30-yr half-Hfe), and plutonium-239 (24,400-yr half-Hfe). 

Wlieii very heavy nuclei, such as those of uranium and plutonium, are split into lighter nuclei having less total mass than the very heavy nuclei, energy is released. The process is called nuclear fission. In either nuclear fission or nuclear fusion, much of the convened rest energy emerges as kinetic energy, heat, and light. 

Commercially, there are only two nuclear species that will function in a self-sustaining nuclear fission chain reaction and Pu (plutonium). 

Uranium-235 and U-238 behave differently in the presence of a controlled nuclear reaction. Uranium-235 is naturally fissile. A fissile element is one that splits when bombarded by a neutron during a controlled process of nuclear fission (like that which occurs in a nuclear reactor). Uranium-235 is the only naturally fissile isotope of uranium. Uranium-238 is fertile. A fertile element is one that is not itself fissile, but one that can produce a fissile element. When a U-238 atom is struck by a neutron, it likely will absorb the neutron to form U-239. Through spontaneous radioactive decay, the U-239 will turn into plutonium (Pu-239). This new isotope of plutonium is fissile, and if struck by a neutron, will likely split. 

Induced nuclear fission is fission caused by bombarding a heavy nucleus with neutrons (Fig. 17.23). The nucleus breaks into two fragments when struck by a projectile. Nuclei that can undergo induced fission are called fissionable. For most nuclei, fission takes place only if the impinging neutrons travel so rapidly that they can smash into the nucleus and drive it apart with the shock of impact uranium-238 undergoes fission in this way. Fissile nuclei, however, are nuclei that can be nudged into breaking apart even by slow neutrons. They include uranium-235, uranium-233, and plutonium-239—the fuels of nuclear power plants. 

Nuclear fission power plants were at one time thought to be the answer to diminishing fossil fuels. Although the enriched uranium fuel was also limited, an advanced nuclear reactor called breeders would be able to produce more radioactive fuel, in the form of plutonium, than consumed. This would make plutonium fuel renewable. Although plutonium has been called one of the most toxic elements known, it is similar to other radioactive materials and requires careful handling since it can remain radioactive for thousands of years. 

Fissile materials are defined as materials that are fissionable by nentrons with zero kinetic energy. In nuclear engineering, a fissile material is one that is capable of snstaining a chain reaction of nuclear fission Nuclear power reactors are mainly fueled with manium, the heaviest element that occurs in natnre in more than trace qnantities. The principal nuclear energy soiuces are maninm-235, plutonium-239, uranium-233 and thorium. 

The most common use of uranium is to convert the rare isotope U-235, which is naturally fissionable, into plutonium through neutron capture. Plutonium, through controlled fission, is used in nuclear reactors to produce energy, heat, and electricity. Breeder reactors convert the more abundant, but nonfissionable, uranium-238 into the more useful and fissionable plutonium-239, which can be used for the generation of electricity in nuclear power plants or to make nuclear weapons. 

The most common use of plutonium is as a fuel in nuclear reactors to produce electricity or as a source for the critical mass required to sustain a fission chain reaction to produce nuclear weapons. Plutonium also is used to convert nonfissionable uranium-238 into the isotope capable of sustaining a controlled nuclear chain reaction in nuclear power plants. It takes only 10 pounds of plutonium-239 to reach a critical mass and cause a nuclear explosion, as compared with about 33 pounds of fissionable, but scarce, uranium-235. 

Uranium-235 is the most important uranium isotope for nuclear fuel. Uranium-238, although not fissionable itself, can be converted into the fissionable plutonium-239 in a breeder reactor by the following nuclear reaction ... 

Bose-Einstein Condensate phase of matter that is created just above absolute zero when atoms lose their individual identity Boyle s Law law that states volume of a gas is inversely related to its pressure Breeder Reactor type of nuclear reactor that creates or breeds fissionable plutonium from nonfissionable U-238 Buckministerfullerene Cg, allotrope of carbon consisting of spherical arrangement of carbon, named after architect Buckmin-ister Fuller, Invertor of geodesic dome Buffer a solution that resists a change in pH... 

Fission weapons or bombs They derive their power from nuclear fission when heavy nuclei such as uranium (U) or plutonium (Pu) are bombarded by neutrons and split into lighter elements, more neutrons and energy. The newly generated neutrons then bombard other nuclei which then split and bombard other nuclei and so on. This process continues and leads to a nuclear chain reaction which releases large amount of energy. These are also historically called atomic bombs or atom bombs or A-bombs. 

Deriving electrical energy from nuclear fission produces almost no atmospheric pollutants, such as carbon dioxide, sulfur oxides, nitrogen oxides, heavy metals, and airborne particulates. Although not discussed in the text, there is also an abundant supply of fuel for nuclear fission reactors in the form of plutonium-239, which can be manufactured from uranium-238. Use the keyword Breeder Reactor on your Internet search engine to learn about how this is so. 

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate. Nuclear reactors are used for many purposes, but the most significant current uses are for the generation of electrical power and for the production of plutonium for use in nuclear weapons. Currently, all commercial nuclear reactors are based on nuclear fission. The amount of energy released by one kg 235U is equal to the energy from the combustion of 3000 tons of coal or the energy from an explosion of 20,000 tons of TNT (Trinitrotoluene, called commonly dynamite). 

In some tests carried out at the Nevada Test Site in 1956-8, fission was incomplete and some plutonium was dispersed. Also some weapons were exploded chemically without nuclear fission in safety tests. Analysis of soil from an area extending about 500 km north-eastwards from the N.T.S. into the neighbouring state of Utah showed excess Pu over the amounts expected from global fallout (Hardy, 1976). The Pu from these low-level, low-yield tests was distinguished from global fallout by two criteria ... 

Commercial nuclear power is generated by nuclear fission reactions. When slow-moving neutrons strike nuclei of uranium-2 3 5 or plutonium-239, these nuclei are split, releasing energy. The energy is used to heat water and drive a turbine, in turn producing electrical energy. Currently nuclear power supplies more than 16 percent of the world s total electricity. 

Nuclear power currently provides 17% of the world s electricity. Heat is generated by nuclear fission of uranium-235 or plutonium-239. This heat is then converted to electricity by boiling water and forcing the steam through a turbine. Fission of and Pu occurs when a neutron strikes the nucleus and breaks it apart into smaller nuclei and additional neutrons. One possible fission reaction is ... 

The first artificial radionuclide, °P, was produced in 1934 by Frederic and Irene Joliot-Curie (daughter and son-in-law of Maria Sklodowska-Curie) by bombarding aluminium with protons in an accelerator [4]. Today, more than 2000 artificial radionuclides have been produced and identified, especially after the discovery and use of nuclear fission of uranium U and plutonium Pu. 

The properties of isotopes. Packing fraction. Structure of atomic nuclei. Nuclear fission. Nuclear chain reaction. Manufacture of plutonium. Fission of U23 and Pu23 . Uranium reactors the uranium pile. Nuclear energy as a source of power. 

When neutrons strike the nucleus of a large atom, they cause that nucleus to split apart into two roughly equal pieces known as fission products. In that process, additional neutrons and very large amounts of energy are also released. Only three isotopes are known to be fissionable, uranium-235, uranium-233, and plutonium-239. Of these, only the first, uranium-235, occurs naturally. Pluto-nium-239 is produced synthetically when nuclei of uranium-238 are struck by neutrons and transformed into plutonium. Since uranium-238 always occurs along with uranium-235 in a nuclear reactor, plutonium-239 is produced as a byproduct in all commercial reactors now in operation. As a result, it has become as important in the production of nuclear power as uranium-235. Uranium-233 can also be produced synthetically by the bombardment of thorium with neutrons. Thus far, however, this isotope has not been put to practical use in nuclear reactors. 

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