Gadolinium Nitrate Solution Research Articles

Detection of Corrosion in aircraft aluminum alloys

This work shows the application of an aqueous solution of gadolinium nitrate as a contrast agent in samples of AA7075 aluminum alloy used in aircraft structures for neutron radiography (NR) detection of corrosion as the pitting and exfoliation, either hidden or not, by the same alloy. Besides this, inspection for detection of simulated corrosions of several dimensions inside a cylindrical block of aluminum alloy was carried out. The neutron radiographies were taken in the NR device of the external thermal column of the Argonaut reactor, Nuclear Engineering Institute, IEN/CNEN. An image detector was used, consisting of a gadolinium converter, 50 μm thick, and a double-coated Kodak Industrex M film.

Magnetically controlled convection in a paramagnetic fluid

CONVECTION in a liquid is important for problems involving heat transfer and crystal growth from a melt. The driving force for convection is usually the density difference between hot and cold regions of the fluid. If the fluid has a magnetic susceptibility that varies with temperature, magnetic forces, rather than buoyancy, can be made to drive convective motion. Studies on ferrofluids (suspensions of ferromagnetic particles1) have shown that magnetic convection can be initiated in a homogeneous magnetic field2,3 and enhanced in a field gradient4. We show here that the strong magnetic fields available from superconducting magnets can be used to induce magnetic convection in normal paramagnetic fluids, such as solutions of paramagnetic salts or melts of paramagnetic solids. We have used a magnetic field both to enhance and to suppress buoyancy-driven convection in a solution of gadolinium nitrate, the sign of the effect depending on the relative orientation of magnetic-field and temperature gradients. The effect might be exploited in heat-transfer devices or to control microstructures in crystal growth.

Radiolysis of aqueous solutions of gadolinium nitrate

The specific effect due to Gd3+ ion on the radiolysis of aqueous nitrate solutions was determined by measurement of H2, H2O2 and NO 2 − radiolytic yields produced by gamma-irradiation of aerated and deaerated solutions of gadolinium, sodium and calcium nitrates in the concentration range of 10−5 to 0.3M. Important O2 consumption in aerated and O2 evolution in deaerated Gd(NO3)2 solutions was found by radiolysis in comparison with the inert cations nitrates. In the former the Gd3+ ion generates an O2 transporter producing an increase in the H2O2 yield and a decrease in the NO 2 − yield, while in the latter it enhances the H2 and NO 2 − production with respect to the same nitrate concentration of the Na+ solutions.

Effect of cerium addition on the thermal stability of gamma alumina support

Effect of cerium addition on the thermal stability of gamma alumina support

The Application of Neutron Radiography to the Study of Microcracking in Concrete

Abstract Radiography of concrete specimens using a neutron flux as the penetrating radiation has been used to identify and study microcracking. The key to the technique is the partial impregnation of the microcracks with a medium with a high neutron attenuation capacity, so as to result in a sharp contrast between the cracks and the surrounding solid mass. Gadolinium has been used as the neutron-attenuating contrast agent, which is applied in the form of an aqueous solution of gadolinium nitrate. The resulting radiographs are compared with more conventional X-ray studies of the same specimens. Neutron radiography appears to be more effective than X-radiography for the identification of cracking.

Study of complexing reactions causing the depletion of gadolinium ions from the moderator of CANDU‐PHW nuclear reactors

AbstractThe addition of gadolinium nitrate solution in the moderator of Hydro‐Québec's Gentilly 2 reactor led to an unexpected depletion of gadolinium (Gd) by precipitation. Analysis of moderator samples revealed that bicarbonate (HCO3−) was the main anionic impurity. A study of the complexing reactions of Gd in concentrated solutions (0.0509M) of Gd(NO3)3 showed that in the absence of HCO3− and at pH < 6, the species in equilibrium are distributed as follows: predominant: Gd3+, NO3− and [GdNO3]2+; and traces: [GdOH]2+ and [Gd(NO3)2]+. An increase in pH over 6.4 led to the formation of the solid phase: Gd2(OH)5.1(NO3)0.9. In the presence of bicarbonate, the solid phase Gd2(OH)5.0(NO3)1.0 is visually detected at a pH as low as 5.8. In other respects, analysis of dilute solutions (0.00065M) of Gd(NO3)3 containing bicarbonate allows the solid phase precipitating between pH 5.5 and 6.6 to be ascribed to the formula Gd2(OH)4CO3·3H2O. In the absence of HCO3−, no precipitation occurred up to pH 6.8. Finally, the loss of Gd from the moderator was established as being due to the formation of a hydroxide carbonate salt.

Corrosion resistance of OKh18N10T steel in gadolinium nitrate solutions in the liquid regulation of the reactivity of nuclear reactors

This study was carried out in connection with the preparation of the design for the PIK research reactor. The corrosion resistance of 0Kh18N10T steel in gadolinium nitrate solutions was tested in laboratory, ampule, and loop corrosion tests. At all stages of the tests, the authors investigated the effect produced on the corrosion processes by factors related to the technology of preparation of the equipment (mechanical working of the surfaces, welding, sensitizing, annealing, stressed state of the material, cracks, etc.). Ampule tests were conducted in order to determine the effect produced by reactor radiation and shutdown regimes on the corrosion resistance of the steel. Special ampules made of 0Kh18N10T steel were filled with gadolinium nitrate solutions of various concentrations, sealed, and irradiated for a long period in the core of the VVR-M reactor at a temperature of 20-50 degrees C. The results of the tests are shown. The investigations showed that the corrosion of 0Kh18N10T steel in solutions of gadolinium nitrate is uniform, regardless of the state of the surface, the concentration of gadolinium nitrate, the duration of the tests, the action of the reactor radiation under static and dynamic conditions, and the presence of mechanical stresses.

Radiolysis of aqueous solutions of gadolinium nitrate

The use of gadolinium nitrate for liquid regulation of the reactivity of nuclear reactors is attractive because this substance has a large neutron-absorption cross section and is highly soluble in coolants. The authors carried out experimental investigations on a special loop of the VVR-M reactor. The investigations established that gadolinium nitrate in aqueous solutions is a radiation-stable chemical compound and can be used as a neutron absorber in the liquid regulation of the reactivity of low temperature nuclear reactors. Nitrogen or air may be used as the gaseous cushion of the volume compensator. The radiolysis of water in the presence of gadolinium nitrate in a closed system leads to the generation of a gaseous phase containing a detonating mixture of H/sub 2/ and O/sub 2/. In an open system with degassing no generation of a gaseous phase is observed. The results of the investigations have been used in designing the liquid reactivity regulation system of the PIK reactor.

Interactions in lanthanide systems—III. A reinvestigation of Raman intensities of aqueous gadolinium nitrate solutions

Interactions in lanthanide systems—III. A reinvestigation of Raman intensities of aqueous gadolinium nitrate solutions

Preparation and properties of nitrate-deficient gadolinium nitrate solutions

Gadolinium nitrate solutions (∼0.001 M) were made nitrate-deficient by contact with hydroxyl-form anion exchange resin. These metastable solutions aged with a decrease in pH and in the amount of soluble gadolinium. Gamma irradiation with 60Co increased the rate of aging. Nitrate deficiency was qualitatively detected and quantitatively determined. At ∼23°C, the solubility product constant K sp, of gadolinium hydroxide in an aged and irradiated solution in H 2O was 10 −26.8; for an aged solution in D 2O, K sp was 10 −26.6.

Interactions in Lanthanide Systems. I. A Raman and Infrared Study of Aqueous Gadolinium Nitrate

Raman spectra of aqueous gadolinium nitrate solutions, and complementary infrared spectra, have been obtained for a wide range of compositions. Detailed intensity analyses indicate that the predominant species in solutions with nitrate:gadolinium ratios less than two is Gd(NO3)2+ (β2 = 4.6 ± 0.2 at 25°C). Small concentrations of a 1:1 species are not excluded but β1 < 0.8. Higher species are significant for ratios of 3 or greater. In systems of low water content evidence is presented for a bridging, polynuclear aggregate which is fragmented by heating or addition of water or nitrate ion. Band assignments are made for the ligand. The nitrate ions in the dinitratogadolinium(III) species are not equivalent: One binds through two oxygen atoms and the other through one.

Effect of solvent on the paramagnetic relaxation constants in liquid solutions of gadolinium nitrate

Effect of solvent on the paramagnetic relaxation constants in liquid solutions of gadolinium nitrate