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PowerPedia:Transmutation

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: See also: Directory:Transmutation

Transmutation is the conversion of one object into another.

Transmutation of There was an error working with the wiki: Code[5] spontaneously decay over a long period of time and transform into other more stable elements. Artificial transmutation occurs in

machinery that has enough energy to cause changes in nuclear structure of the elements. The machines that can cause artificial transmutation include the There was an error working with the wiki: Code[10] and There was an error working with the wiki: Code[11] reactor.

Introduction

Transmutation is the conversion of one object into another. It is most commonly used in reference to extremely basic objects, for example turning lead to gold or gold to pure energy, but can be used to refer to more complex objects as well, as in transmogrification.

Transmutation of chemical elements occurs through nuclear reactions. This is called nuclear transmutation. Natural transmutation is when radioactive elements spontaneously decay over a long period of time and transform into other more stable elements, while artificial transmutation is when atoms are bombarded with a stream of particles in a particle accelerator, or are otherwise coerced by high-energy means (such as in a tokamak reactor), to induce transmutation.

Photoneutron process

Transmutation of the elements can occur naturally or artificially by the photoneutron process. A Gamma ray (high-energy photon) with an energy greater than the neutron binding force can eject a neutron from a stable nucleus to cause transmutation to another element.

A 6.8 Mev Gamma ray can eject a neutron from the nucleus of Mercury isotope 198. The resulting Mercury isotope

197 is radio-active (half-life 2.7 days), decaying into Gold isotope 197. Mercury isotope 198 is 10% of naturally

obtained Mercury. The There was an error working with the wiki: Code[12] completed in 2006 at Oak Ridge National Laboratory causes

transmutation of Mercury to Gold and other precious metals below Gold in atomic mass.[http://www.sns.gov/]

Origin

The term dates back to the search for the There was an error working with the wiki: Code[13]. It was applied consciously to modern physics first by There was an error working with the wiki: Code[14] when he, along with There was an error working with the wiki: Code[15], discovered that radioactive There was an error working with the wiki: Code[16] was converting itself into There was an error working with the wiki: Code[17] in There was an error working with the wiki: Code[18]. At the moment of realization, Soddy later recalled, he shouted out: "Rutherford, this is transmutation!" Rutherford snapped back, "For Christ's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists."

Overview

Transmutation of There was an error working with the wiki: Code[19] (actinides) such as the There was an error working with the wiki: Code[20]s of There was an error working with the wiki: Code[21], There was an error working with the wiki: Code[22], There was an error working with the wiki: Code[23], and There was an error working with the wiki: Code[24] has the potential to help solve the problems posed by the management of There was an error working with the wiki: Code[25], by reducing the proportion of long-lived isotopes it contains. When irradiated with There was an error working with the wiki: Code[26] in a There was an error working with the wiki: Code[27], these isotopes can be made to undergo Nuclear fission, destroying the original There was an error working with the wiki: Code[28] isotope and producing a spectrum of radioactive and nonradioactive There was an error working with the wiki: Code[29].

Transmutation of transuranium elements (actinides) such as the isotopes of plutonium, neptunium, americium, and curium has the potential to help solve the problems posed by the management of radioactive waste, by reducing the proportion of long-lived isotopes it contains. When irradiated with neutrons in a nuclear reactor, these isotopes can be made to undergo nuclear fission, destroying the original actinide isotope and producing a spectrum of radioactive and nonradioactive fission products.

Reactor types

For instance, plutonium can be reprocessed into There was an error working with the wiki: Code[30] fuels and transmuted in standard reactors. The heavier elements could be transmuted in There was an error working with the wiki: Code[31]s, but probably more effectively in a There was an error working with the wiki: Code[32]which is sometimes known as an <pesn type=.

Reasoning behind transmutation

Isotopes of plutonium and other actinides tend to be long-lived with There was an error working with the wiki: Code[6]s of many thousands of years, whereas radioactive fission products tend to be shorter-lived (most with half-lives of 30 years or less). From a waste management viewpoint, transmutation of actinides eliminates a very long-term radioactive hazard and replaces it with a much shorter-term one.

It is important to understand that the threat posed by a radioisotope is influenced by many factors including the There was an error working with the wiki: Code[34] and There was an error working with the wiki: Code[35] properties of the element. For instance There was an error working with the wiki: Code[36] has a relatively short There was an error working with the wiki: Code[37] (1 to 4 months) while There was an error working with the wiki: Code[38] and There was an error working with the wiki: Code[39] has a very long biological half-life. As a result strontium-90 and radium are much more able to cause harm than cesium-137 when a given activity is ingested.

Many of the actinides are very radiotoxic because they have long biological half-lives and are There was an error working with the wiki: Code[40] emitters. In transmutation the intention is to convert the actinides into There was an error working with the wiki: Code[41]. The fission products are very radioactive, but the majority of the activity will decay away within a short time. The most worrying shortlived fission products are those that accumulate in the body, such as There was an error working with the wiki: Code[42]-131 which accumulates in the thyroid gland, but it is hoped that by good design of the There was an error working with the wiki: Code[43] and transmutation plant that such fission products can be isolated from man and his environment and allowed to decay. In the medium term the fission products of highest concern are strontium-90 and cesium-137 both have a half life of about 30 years. The cesium-137 is responsible for the majority of the external There was an error working with the wiki: Code[44] dose experienced by workers in There was an error working with the wiki: Code[45] plants and at this time (2005) to workers at the There was an error working with the wiki: Code[46] site. When these medium-lived isotopes have decayed the remaining isotopes will pose a much smaller threat.

In stars

Gold is actually created by There was an error working with the wiki: Code[7], which however transmute a lot of it into lead - a much easier process. Gold is valuable, precisely because it is a rather rare product. The alchemical belief in transmutation was based on a thoroughly wrong understanding of the underlying processes. There was an error working with the wiki: Code[8] first identified the chemical elements and There was an error working with the wiki: Code[9] restored the Greek notion of Atoms to explain chemical processes. The disintegration of atoms is a distinct process involving much greater energies.

Genuine scientific transmutation is nicely described in There was an error working with the wiki: Code[47]'s book There was an error working with the wiki: Code[48]. He summarised the process as:

:::::Burbidge, Burbidge, Fowler, Hoyle

:::::Took the stars and made them toil:

:::::Carbon, copper, gold, and lead

:::::Formed in stars, is what they said

This summarises Synthesis of the Elements in Stars (Reviews of Modern Physics, vol. 29, Issue 4, pp. 547–650), by There was an error working with the wiki: Code[49]. There was an error working with the wiki: Code[50], There was an error working with the wiki: Code[51], and There was an error working with the wiki: Code[52], which was published in 1957. The paper explained how the abundances of essentially all but the lightest chemical elements could be explained by the process of nucleosynthesis in stars. Hoyle correctly predicted a previously unknown energy level for carbon on this basis.

Alchemy

In There was an error working with the wiki: Code[53], it is believed that such transformations can be accomplished in table-top experiments and some researchers say they have found evidence of transmutation of elements in biological processes (see There was an error working with the wiki: Code[54]). These theories are regarded as There was an error working with the wiki: Code[55] by virtually all modern There was an error working with the wiki: Code[56].

Modern nuclear experiments have successfully transmuted lead into gold. The great expense of the procedure, however, far exceeds any financial gainhttp://chemistry.about.com/cs/generalchemistry/a/aa050601a.htm. In many ways it would be easier to convert gold into lead by nuclear means. By leaving gold in a high flux nuclear reactor for a long time then some lead could be generated.

197Au n --> 198Au (half life 2.7 days) --> 198Hg n --> 199Hg n --> 200Hg --> n --> 201Hg --> n --> 202Hg n --> n --> 203Hg (half life 47 days) --> 203Tl n --> n --> 204Tl (half life 3.8 years) --> 204Pb (half life 1.4 x 1017 years)

Accelerated radioactive decay

Accelerated radioactive decay using intense magnetic fields

Various scientists have proposed bombarding spent fuel with electromagnetic rays to accelerate the decay process. This is different than transmutation, although some concepts use spallation (as does transmutation). Gamma rays have been suggested very effective, but gamma rays are very difficult to produce and may need to be precisely tuned to the target actinide or fission product.

In 2006, Professor Howard R Reiss, former departmental head for nuclear physics in the United States Navy, has proposed using high-intensity radio waves (in the AM band). He believes his method can increase the decay rate 10 times, and he intends to organize experiments to prove this.

Cold fusion

Cold fusion is a process in which various researchers claim elements can be transmuted at or near room temperature in metallic catalysts. It is generally rejected as pathological science (for example due to calling of press conferences before results could be duplicated), but research is ongoing. The main experiment at the core of the cold fusion story was electrochemical (electrolytic cell), but some workers (Yasuhiro Iwamura) reported transmutation in other systems such as during the transport of deuterium gas through a palladium wall into a vacuum.

Related

External articles

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Advanced Accelerator Applications (AAA):Transmutation of Waste. Advantages of Transmutation.

Transmutation of Radioactive Waste Program of the NEA Data Bank of the OECD. Includes a general introduction to transmutation of radioactive waste and information on Transmutation with nuclear.

There was an error working with the wiki: Code[1], Wikipedia: The Free Encyclopedia. Wikimedia Foundation.

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See also

Directory:Transmutation

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