Nuclear energy industry boron used

Elemental boron is also used in the nuclear energy industry. Boron readily absorbs neutrons and is used in the confiol rods of nuclear reactors. When the nuclear reaction needs to be slowed down, the rods are inserted into the reactor to absorb the neutrons (see Section 19.7). 

A short description of possible nuclear applications of boron-based materials had been done by Potapov (1961) in an old overview that included the nuclear power industry (e.g., control rods of nuclear reactors) solid-state electronics (e.g., counters of neutrons and neutron energy sensors) radiation chemistry (e.g., acceleration of technological processes) etc. For these purposes, "B nuclei are useless, but °B nuclei are useful due to a large cross section of interaction with thermal neutrons, °B converts them into heavy ionizing particles. Besides, °B isotope is applicable for neutron radiation protection (Stantso 1983) and also in medicine, e.g., in boron neutron capture therapy (BNCT) for treating cancer tumors (Desson 2007). 

Two of the metals, uranium and thorium, have an obvious connection with the atomic energy industry which has arisen during and since the 1939-45 war, and have no major uses, in metallic form, outside that field. They are required mainly as fuels for nuclear reactors and their standards of purity are probably greater than those of any other metals which have been produced on a similar scale. This arises partly because trace impurities such as silicon or iron might confer adverse metallurgical properties, but is chiefiy because of the necessity to exclude minute quantities of elements with high neutron-capture cross-sections . Specification limits for boron, cadmiiun and some rare earth elements, for example, may be quite realistically fixed at a fraction of 1 ppm. 

The fundamental chemical principle behind the isotopic offset between the two aqueous boron species relates primarily to vibrational and rotational energy differences between the two isotopes, such that the heavier isotope is preferentially incorporated into the trigonal species. The motivation for studying this fractionation was for the nuclear industry, as has a very high cross section for neutron captme, and so is used as a neutron flux absorber. Mechanisms for enriching from natural boron led to studies that showed it could be separated from "B on ion exchange columns. Theoretical approaches were used to calculate the fractionation factor a, which describes the isotopic offset between two phases. 

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