Major actinides
From ArticleWorld
The term major actinides is used to refer to the elements uranium and plutonium which are used in nuclear fuel. The actinide series of the periodic table of all chemical elements encompasses a total of 15 elements that lie between actinium and lawrencium, which have atomic numbers from 89 to 103.
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The occurrence of actinides
Of the 15 elements in the series, only actinium, thorium and uranium occur in the natural form in the earth's crust. They are present in traces inside the crust; the elements neptunium and plutonium are also found naturally but only because of the decay of uranium ores. The other actinide elements were discovered as a result of nuclear accidents or warfare. Some of the elements of this radioactive series possess half-lives that are extremely short; such elements are known to exist only for fractions of seconds before their atoms disintegrate into atoms of other elements by radioactive decay.
The major actinides –Uranium and Plutonium
The word major is used to describe these actinide elements because of their feasibility in both civilian power generation purposes and in building the so-called 'nuclear deterrent capability' of the world's nuclear states.
Uranium
Uranium has atomic number 92 and is found as an oxide or in salts such as pitchblende in traces in the earth's crust. It has an atomic weight of 238.03 and has isotopes ranging from 222 to 242 in their mass numbers.
Plutonium
Plutonium has atomic number of 94 and is found in traces in ores of uranium. As many as 15 different isotopes of plutonium are known, and they range from mass numbers 232 to 246. Plutonium is produced by bombarding uranium-238 by slow neutrons. This results in neptunium-239, which further emits a beta particle and forms plutonium-239.
The major actinides, namely uranium and plutonium have been a subject of concern among the world's major political powers because of their use in the highly-destructive nuclear weapons. These elements can be enriched by using suitable enrichment methods that can enhance their purity and make them suitable for dangerous nuclear reactions. A fission reaction that is set off from masses of these elements can release vast amounts of energy that can make nuclear weapons several thousand times more destructive than pieces of conventional munitions.
Use of uranium for peaceful purposes
However, if uranium is enriched to certain low levels, it can be used as a nuclear fuel for peaceful, civilian purposes like generation of electricity. There are other major engineering fields which can benefit from nuclear technology; for example, plastics technology, wherein wood and plastic can be blended to form a material with greater mechanical strength and durability. Nuclear energy can also be used to divert rivers and prevent floods.