Niobium nuclear properties

Because of favourable nuclear properties of these matrices, several nuclear reactions can be used for the instrumental determination of nitrogen in niobium and tantalum. 

Niobium-Vanadium The presence of vanadium reduces niobium s corrosion resistance to most media. The alloy containing 12 6 at. Vo V however has excellent resistance to high-temperature water and steam, and this property and the alloy s relatively low neutron cross section give it considerable potential for nuclear applications. 

Our life would never be as advanced and comfortable as it is if not for the applications of tantalum and niobium. These materials unique properties ensure their increasing usage in electronic, optic, mechanical, aerospace, nuclear and other modem applications. 

Because hafnium has a high absorption cross-section for thermal neutrons (almost 600 times that of zirconium), has excellent mechanical properties, and is extremely corrosion resistant, it is used to make the control rods of nuclear reactors. It is also applied in vacuum lines as a getter —a material that combines with and removes trace gases from vacuum tubes. Hafnium has been used as an alloying agent for iron, titanium, niobium, and other metals. Finely divided hafnium is pyrophoric and can ignite spontaneously in air. 

Properties Dense, silvery solid. D 19.0, mp 1132C, bp3818C, heat of fusion 4.7 kcal/mole, heat capacity 6.6 cal/mole/C. Strongly electropositive, ductile and malleable, poor conductor of electricity. Forms solid solutions (for nuclear reactors) with molybdenum, niobium, titanium, and zirconium. The metal reacts with nearly all nonmetals. It is attacked by water, acids, and peroxides, but is inert toward alkalies. Green tetravalent uranium and yellow uranyl ion (U()2") are the only species that are stable in solution. 

Pure niobium has relatively poor mechanical properties and readily oxidizes in air to niobium pentoxide (Nb205) at elevated temperatures. Various niobium-containing alloys such as Nb-lZr and C-103 have been successfully used in specific liquid-metal based nuclear applications and in the fabrication of various rocket components, see also Inorganic Chemistry. 

Other materials such as zirconium and niobium in solid solution may be deliberately incorporated in the fuel to alter the properties to those needed for the reactor design. Also, it is generally advantageous for some of the products of the nuclear reaction to remain in solid solution in the fuel, rather than accumulating as separate phases. 

Niobium and tqntalum have similar chemical properties and the normal methods of niobium extraction do not remove the tantalum. Separation of these two elements is necessary, for example, when the niobium is required for nuclear purposes, and several solvent extraction processes are suitable. Hexone i (methyl isobutyl ketone) and tributyl phosphatei are the two principal solvents which are used, although processes have also been developed using methyl dioctylaminei and di-isopropyl ketone.i ... 

Other metals such as beryllium, hafnium, niobium, vanadium, and zirconium are known to have nuclear and other properties which make them desirable materials of construction in various designs of nuclear reactor, but also they have, or may have in the future, important uses outside that field. All these metals except hafnium have been used or proposed for canning materials to clad and protect the nuclear fuel metals from corrosion by the reactor coolants or moderators, air, carbon dioxide, water, heavy water, graphite or molten sodium, etc. In some cases the specifications for neutron-absorbing impurities are of the same order as for the fuel metals uranium and thorium. Hafnium, however, with a high neutron-capture cross-section, is a useful material for reactor control rods and exhibits favourable metallurgical properties under irradiation. 

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