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Thorium is a chemical element. It has the symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive gray when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high melting point. Thorium is an electropositive actinide whose chemistry is dominated by the ...
The only nuclear state suitable for the development of a nuclear clock using existing technology is thorium-229m, a nuclear isomer of thorium-229 and the lowest-energy nuclear isomer known. With an energy of 8.355 733 554 021 (8) eV , [ 3 ] [ 4 ] [ 5 ] this corresponds to a wavelength of 148.382 182 883 nm in the vacuum ultraviolet region ...
Thorium reacts with hydrogen to form the thorium hydrides ThH 2 and Th 4 H 15, the latter of which is superconducting below the transition temperature of 7.5–8 K; at standard temperature and pressure, it conducts electricity like a metal. [12] Thorium is the only metallic element that readily forms a hydride higher than MH 3. [31]
The 4n chain of thorium-232 is commonly called the "thorium series" or "thorium cascade". Beginning with naturally occurring thorium-232, this series includes the following elements: actinium, bismuth, lead, polonium, radium, radon and thallium. All are present, at least transiently, in any natural thorium-containing sample, whether metal ...
Thorium-234. 234Th is an isotope of thorium whose nuclei contain 144 neutrons. 234 Th has a half-life of 24.1 days, and when it decays, it emits a beta particle, and in doing so, it transmutes into protactinium -234. 234 Th has a mass of 234.0436 atomic mass units, and it has a decay energy of about 270 keV.
The thorium fuel cycle is a nuclear fuel cycle that uses an isotope of thorium, 232. Th. , as the fertile material. In the reactor, 232. Th. is transmuted into the fissile artificial uranium isotope 233. U. which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as 231.
The design of some SMR reactors is based on the thorium fuel cycle, which is considered by their promotors as a way to reduce the long-term waste radiotoxicity compared to the uranium cycle. [45] However, using the thorium cycle also presents big operational challenges because of the production and the use of 232 U and long-lived fertile 233
Protactinium-233 occurs as a result of the decay of thorium-233 as part of the chain of events necessary to produce uranium-233 by neutron irradiation of thorium-232. It is an undesired intermediate product in thorium-based nuclear reactors, and is therefore removed from the active zone of the reactor during the breeding process. Ocean science ...