Marcel TUDOR
13.07.2013, 03:21
( information source: https://www.facebook.com/nucleare.rivistascientifica?fref=ts )
The first in a series of posts on the Flibe Energy blog describing the history of thorium as an energy source, and the development of the molten-salt reactor.
http://flibe-energy.com/?p=637 (http://flibe-energy.com/?p=637)
History, part 1
Posted by kfsorensen (http://flibe-energy.com/?author=4) on 2013/05/13 with 0 Comments (http://flibe-energy.com/?p=637#comments)
From its discovery in 1828 until 1898, there was little to distinguish thorium (http://en.wikipedia.org/wiki/Thorium) from the other eighty or so elements that had been discovered. It was not terribly uncommon in the Earth’s crust, accounting for about six parts per million on average. It attained some degree of commercial usefulness in 1890, when Carl Auer von Welsbach (http://en.wikipedia.org/wiki/Carl_Auer_von_Welsbach) showed howthorium dioxide (http://en.wikipedia.org/wiki/Thorium_dioxide) could be used in the mantle of a gas lantern, giving off a glorious white light.
In 1896, Henri Becquerel (http://en.wikipedia.org/wiki/Henri_Becquerel) discovered that uranium was emitting rays that caused a photographic plate to darken, even when it was kept from exposure in a drawer. His discovery intrigued 28-year old Marie Sklodowska Curie (http://en.wikipedia.org/wiki/Marie_Sk%C5%82odowska-Curie), a Polish physicist and chemist who worked with Becquerel along with her husband Pierre (http://en.wikipedia.org/wiki/Pierre_Curie). Curie and her husband began a campaign to examine all materials to discover if they also displayed the “radioactivity (http://en.wikipedia.org/wiki/Radioactivity)” that Becquerel had seen in uranium. In 1898 she noted:
I examined a large number of metals, salts, oxides, and minerals.
All the uranium compounds studied are active, and are, in general, more active to the extent that they contain more uranium.
The compounds of thorium are very active. Thorium oxide surpasses even metallic uranium in activity.
It is remarkable that the two most active elements, uranium and thorium, are the ones which possess the greatest atomic weight.
Source (http://web.lemoyne.edu/~giunta/ea/curieann.html)
Her discovery that thorium was also radioactive, and the penetrating insight that thorium and uranium were the two elements with the greatest atomic masses, was one of the key intellectual steps that would lead to a revolution in our understanding of atomic structure.
http://mariecurietpe.unblog.fr/files/2010/11/mariecurie.jpg
Within a few decades, the notion of an atom (http://en.wikipedia.org/wiki/Atom) as an impenetrable, unchangeable sphere of particular composition had given way to our current understanding of the atom—a positively charged nucleus (http://en.wikipedia.org/wiki/Atomic_nucleus) composed of protons and neutrons, surrounding by tiny orbiting electrons (http://en.wikipedia.org/wiki/Electrons) in a variety of orbital configurations.
Furthermore, it was come to be understood that there were further forces acting at the scale of the nucleus that made the structure of matter possible. They had previously been indetectable due to their very short ranges, but without them there would be no reasonable explanation for the structure of matter or the order of the universe.
The most basic of these was the nuclear force (http://en.wikipedia.org/wiki/Nuclear_force), or the strong nuclear force as it is known today. The nucleus is composed of positively-charged protons and neutrons that have no electrical charge. Based on an understanding of electromagnetic forces (which was correct) these positively-charged protons should be continuously attempting to rip the nucleus apart, since electric charges of the same sign repel one another. This repulsion grows stronger and stronger the closer the particles are to one another, and by all indications, the protons were very very close together.
The neutrons should be no help at all in this situation, since they had no charge. But the nuclear force, as postulated, was a force that strongly bound nucleons (protons and neutrons) together. It had the ability, somehow, to overcome these forces of electric repulsion and to make nuclear structure possible. Now we understand these forces come from interactions of subatomic particles, quarks and gluons, which form the structure of nucleons.
The strong nuclear force also helped uncover the mystery of radiation, and why various nuclear configurations, particularly those associated with very heavy nuclear masses, were unstable and radioactive.
Next: Three Decay Chains, One Missing… (http://flibe-energy.com/?p=640)
Filed Under: Blog (http://flibe-energy.com/?cat=6)
Comments are closed.
The first in a series of posts on the Flibe Energy blog describing the history of thorium as an energy source, and the development of the molten-salt reactor.
http://flibe-energy.com/?p=637 (http://flibe-energy.com/?p=637)
History, part 1
Posted by kfsorensen (http://flibe-energy.com/?author=4) on 2013/05/13 with 0 Comments (http://flibe-energy.com/?p=637#comments)
From its discovery in 1828 until 1898, there was little to distinguish thorium (http://en.wikipedia.org/wiki/Thorium) from the other eighty or so elements that had been discovered. It was not terribly uncommon in the Earth’s crust, accounting for about six parts per million on average. It attained some degree of commercial usefulness in 1890, when Carl Auer von Welsbach (http://en.wikipedia.org/wiki/Carl_Auer_von_Welsbach) showed howthorium dioxide (http://en.wikipedia.org/wiki/Thorium_dioxide) could be used in the mantle of a gas lantern, giving off a glorious white light.
In 1896, Henri Becquerel (http://en.wikipedia.org/wiki/Henri_Becquerel) discovered that uranium was emitting rays that caused a photographic plate to darken, even when it was kept from exposure in a drawer. His discovery intrigued 28-year old Marie Sklodowska Curie (http://en.wikipedia.org/wiki/Marie_Sk%C5%82odowska-Curie), a Polish physicist and chemist who worked with Becquerel along with her husband Pierre (http://en.wikipedia.org/wiki/Pierre_Curie). Curie and her husband began a campaign to examine all materials to discover if they also displayed the “radioactivity (http://en.wikipedia.org/wiki/Radioactivity)” that Becquerel had seen in uranium. In 1898 she noted:
I examined a large number of metals, salts, oxides, and minerals.
All the uranium compounds studied are active, and are, in general, more active to the extent that they contain more uranium.
The compounds of thorium are very active. Thorium oxide surpasses even metallic uranium in activity.
It is remarkable that the two most active elements, uranium and thorium, are the ones which possess the greatest atomic weight.
Source (http://web.lemoyne.edu/~giunta/ea/curieann.html)
Her discovery that thorium was also radioactive, and the penetrating insight that thorium and uranium were the two elements with the greatest atomic masses, was one of the key intellectual steps that would lead to a revolution in our understanding of atomic structure.
http://mariecurietpe.unblog.fr/files/2010/11/mariecurie.jpg
Within a few decades, the notion of an atom (http://en.wikipedia.org/wiki/Atom) as an impenetrable, unchangeable sphere of particular composition had given way to our current understanding of the atom—a positively charged nucleus (http://en.wikipedia.org/wiki/Atomic_nucleus) composed of protons and neutrons, surrounding by tiny orbiting electrons (http://en.wikipedia.org/wiki/Electrons) in a variety of orbital configurations.
Furthermore, it was come to be understood that there were further forces acting at the scale of the nucleus that made the structure of matter possible. They had previously been indetectable due to their very short ranges, but without them there would be no reasonable explanation for the structure of matter or the order of the universe.
The most basic of these was the nuclear force (http://en.wikipedia.org/wiki/Nuclear_force), or the strong nuclear force as it is known today. The nucleus is composed of positively-charged protons and neutrons that have no electrical charge. Based on an understanding of electromagnetic forces (which was correct) these positively-charged protons should be continuously attempting to rip the nucleus apart, since electric charges of the same sign repel one another. This repulsion grows stronger and stronger the closer the particles are to one another, and by all indications, the protons were very very close together.
The neutrons should be no help at all in this situation, since they had no charge. But the nuclear force, as postulated, was a force that strongly bound nucleons (protons and neutrons) together. It had the ability, somehow, to overcome these forces of electric repulsion and to make nuclear structure possible. Now we understand these forces come from interactions of subatomic particles, quarks and gluons, which form the structure of nucleons.
The strong nuclear force also helped uncover the mystery of radiation, and why various nuclear configurations, particularly those associated with very heavy nuclear masses, were unstable and radioactive.
Next: Three Decay Chains, One Missing… (http://flibe-energy.com/?p=640)
Filed Under: Blog (http://flibe-energy.com/?cat=6)
Comments are closed.