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However, the 231 Pa (with a half-life of 3.27 × 10 4 years) formed via (n,2n) reactions with 232 Th (yielding 231 Th that decays to 231 Pa), while not a transuranic waste, is a major contributor to the long-term radiotoxicity of spent nuclear fuel. While 231 Pa can in principle be converted back to 232
Protactinium-231 arises naturally from the decay of natural uranium-235, and artificially in nuclear reactors by the reaction 232 Th + n → 231 Th + 2n and the subsequent beta decay of 231 Th. It was once thought to be able to support a nuclear chain reaction, which could in principle be used to build nuclear weapons ; the physicist Walter ...
One isotope, 229 Th, has a nuclear isomer (or metastable state) with a remarkably low excitation energy, [5] recently measured to be 8.355 733 554 021 (8) eV [6] [7] It has been proposed to perform laser spectroscopy of the 229 Th nucleus and use the low-energy transition for the development of a nuclear clock of extremely high accuracy.
Protactinium (91 Pa) has no stable isotopes.The four naturally occurring isotopes allow a standard atomic weight to be given. Twenty-nine radioisotopes of protactinium have been characterized, ranging from 211 Pa to 239 Pa.
Aluminium's is 75.2 GPa; copper's 137.8 GPa; and mild steel's is 160–169 GPa. [13] Thorium is about as hard as soft steel, so when heated it can be rolled into sheets and pulled into wire. [14] Thorium is nearly half as dense as uranium and plutonium and is harder than both. [14] It becomes superconductive below 1.4 K. [12]
The University of Vic - Central University of Catalonia (UVic-UCC), is a Catalan university with premises in Vic, Manresa and Granollers.It is a privately managed institution, under public supervision through its proprietor, the Balmes University Foundation, whose chair is the Mayor of Vic. UVic-UCC is a higher education and research centre.
Chemical technologists generally require completion of a specific college program—either two year or four year— in chemical, biochemical, or chemical engineering technology or a closely related discipline. [2] They usually work under or with a scientist such as a chemist or biochemist.
The constants listed here are known values of physical constants expressed in SI units; that is, physical quantities that are generally believed to be universal in nature and thus are independent of the unit system in which they are measured.