Reactor control rods

Because the element not only has a good absorption cross section for thermal neutrons (almost 600 times that of zirconium), but also excellent mechanical properties and is extremely corrosion-resistant, hafnium is used for reactor control rods. Such rods are used in nuclear submarines. 

Boron-10 has a natural abundance of 19.61 atomic % and a thermal neutron cross section of 3.837 x 10 m (3837 bams) as compared to the cross section of 5 x 10 m (0.005 bams). Boron-10 is used at 40—95 atomic % in safety devices and control rods of nuclear reactors. Its use is also intended for breeder-reactor control rods. 

Cadmium is an impoitant component in brazing and low melting alloys, used in bearings, solders, and nuclear reactor control rods, and as a hardener for... 

Nuclear reactor applications, artificial graphite in, 72 741-744 Nuclear reactor control rods, indium in, 74 195... 

B is a powerful neutron absorber and has been employed in reactor control rods, neutron detectors, and other applications. Cascades based on exchange distillation of boron-ether complexes have usefully large a s and were used for 10B/UB isotope separation by the US DOE. Exchange distillation takes advantage of the fact that condensed phase/vapor phase separation factors can be enhanced (as compared to liquid/vapor a s) by association/dissociation equilibria in one or the other phase. At the normal boiling point (173 K) the VPIE for... 

There are only a few commercial uses for europium. Europium oxide, (Eu O ), a compound of europium, is added to infra-sensitive phosphors to enhance the red colors on TV and computer-monitor picture tubes. It is also added to fluorescent light tubes to increase their efflciency, as well as to some materials to make lasers. Since it is a good neutron absorber, it is part of nuclear reactor control rods. Europium is an additive to the glue used on postage stamps, thus making it possible for the electronic sorting machines in U.S. postal offices to read the stamps. 

Uses. The metal is used in electroplating, in solder for aluminum, as a constituent of easily fusible alloys, as a deoxidizer in nickel plating, in process engraving, in cadmium-nickel batteries, and in reactor control rods. Cadmium compounds are employed as TV phosphors, as pigments in glazes and enamels, in dyeing and printing, and in semiconductors and rectifiers. 

Gadolinium Oxide, Gd203, mw 362.52 wh to cream-colored powder, sp gr 7.407 at 15/4°, mp 2330° hygroscopic and absorbing C02 from the air insol in w sol in acids except HF. Used in nuclear reactor control rods, neutron shields, catalysts, dielectric ceramics, filament coatings, special glasses and as P activator... 

Use With nickel, in cermets used as nuclear reactor control rods that do not require watercooling. 

Use Nuclear-reactor control rods, especially in red-and infrared-sensitive phosphors. 

Use Automobile bearings, electronic and semiconductor devices, low-melting brazing and soldering alloys, reactor control rods, electroplated coatings... 

The rate of the reaction is modulated by controlling the number and energy of the neutrons allowed to stay in the uranium filled core of the reactor. Control rods are used to modulate the nuclear reaction rate. Control rods are made from an element (cadmium metal is often used) that strongly adsorbs neutrons. The rods are installed in channels in the reactor. When the rods are fully inserted in the reactor, so many neutrons are adsorbed that little reaction can occur. As the rods are withdrawn, more and more neutrons can react and the reactions begin. The reaction rate is controlled by the depth and number of rods inserted in the reactor. 

Zirconium has a high corrosion resistance and low cross-section for neutron capture (see Section 2.4) and is used for cladding fuel rods in water-cooled nuclear reactors. For this application, Zr must be free of Hf, which is a very good neutron absorber. The main use of pure Hf is in nuclear reactor control rods. Zirconium and hafnium compounds possess similar lattice energies and solubilities, and their complexes have similar stabilities this means that... 

USE In bearing alloys as a thin film on moving surfaces made from other metals. In dental alloys. In semiconductor research. In nuclear reactor control rods (in the form of an Ag-In-Cd alloy). 

EINECS 231-180-0 HSDB 6972 Indium. Metallic element, automobile bearings, electronic and semiconductor devices, brazing and soldering alloys, reactor control rods, electroplated coatings on aircraft bearings. Metal mp = 155° bp = 2000 d = 7,3 specific heat = 0.0568 cal/g/ . Atomergic Chemetats Cerac Noah Chem. Sigma-Atdrich Fine Chem. 

Hafnium is a powerful absorber (105 barns) of thermal neutrons. Therefore, it is used in the nuclear industry as a material for reactor control rods (e.g., in nuclear submarines) and for protective screens in reactors. The nuclear industry utilizes about 90% of the total hafnium output. 

Tm). The high thermal neutron absorption cross-sections and high melting points of various lanthanides (Sm, Eu, Dy, Gd) are two properties that make them ideal for use in nuclear reactor control rod applications. Cerium dioxide has been developed into a sunscreen that has higher transparency and higher ultraviolet blocking proper-... 

Control Rods Bombarding uranium-235 with neutrons produces samarium-149, which is used in nuclear reactor control rods. What other element is produced ... 

The bumup reactivity swing has been deduced from the reactivity balances at different moments during the operation of the reactor. Control rod insertions as well as temperature increases have been taken into account to deduce the measured values (using the S curves of the control rod system). Advantage has been taken from the fact that the reactor has had periods without operation to separate the reactivity variation with time into two components the loss of reactivity caused by bumup (heavy nuclide transmutation and fission due to the mnning of the reactor under power), and the loss of reactivity due to the natural " Pu decay. The experimental results used for the comparison with calculation are taken from the first period of the life of the reactor (82.3 FPD over the first 40 months). 

Some of the rare earth nuclei have small capture cross-sections for neutrons, and some have extremely large capture cross-sections. From the practical viewpoint, since the rare earths are formed in fission, such information plays an important role in nuclear energy technology. A knowledge of the cross-section, lifetimes and chemical behavior of the isotopes is extremely important in the design of reactors, control rods, nuclear poisons and reactor waste disposal processes. 

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. 

Indium has many industrial uses for electronics and electrical applications [9] indium metal in germanium transistors indium alloys for soldering and glass sealing of electronic devices indium antimonide, arsenide, and phosphide in infrared detectors and semiconductor applications indium-silver alloys for brazing and electroplated indium metal for electrical connectors. For underground telephone cables, indium has been used to plate copper-to-aluminum connectors. About 2-5 tons of indium alloyed with silver and cadmium has been used annually in nuclear reactor control rods. 

Because hafnium has an elevated absorption cross section for thermal neutrons (almost 565 times that of zirconium), it is extensively used for producing nuclear-reactor control rods. On the other hand, hafnium carbide is the most refractory binary composition known, and the nitride is the most refractory of all known metal nitrides m.p. 3310 C). To a lesser extent, hafnium is used in gas-filled and incandescent lamps as an efficient getter for scavenging oxygen and nitrogen, and alloying with iron, titanium, niobium, and other refractory metal alloys. 

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