Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Neutron & Zirconium alloy. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Ordered bed packing module

Abstract: In one embodiment of the invention a catalyst packing module is provided which greatly enhances the vapour-liquid transfer rate in the overall hydrogen-liquid water isotopic exchange reaction between streams of gaseous hydrogen and liquid water. The catalyst packing module comprises alternate layers of plane sheet and corrugated sheet and is produced by rolling at least one plane sheet and at least one corrugated sheet together into a right cylinder in a jelly roll configuration. The plane sheet is a woven, knitted or felted cloth of a textile material which wicks water over its surface and the corrugated sheet is an open mesh of metal coated with a porous matrix of polytetrafluoroethylene with exposed, partially platinized carbon particles therein. This catalyst packing module maximizes the hydrophilic surface area per unit volume of packing for the vapour-liquid transfer reaction and also the surface area of the support material (carrier) for the hydrophobic catalyst. Although the packing is tight, high gas and liquid flow can be used without flooding the bed because the hydrophilic surfaces are separated by hydrophobic spacers and because the hydrophilic surface have a wicking action. In other embodiments of the invention the packing module is used to advantage for any gas-liquid transfer reaction but in this application the corrugated mesh is a metal cloth, does not support a catalyst and is made hydrophobic with, or of, some suitable polymeric material such as polytetrafluoroethylene, polyethylene, polystyrene, polymethacrylate, polypropylene etc.

Radionuclide migration over recent geologic time in a granitic pluton

Abstract: Measurements of isotope activity ratios in the 238 U decay series have been made for core samples obtained from boreholes up to 1-km depth in the Eye-Dashwa Lakes granite pluton, Atikokan, northwest Ontario, Canada. This work was done to determine the significance of recent radionuclide migration in plutonic rocks for the Canadian Nuclear Fuel Waste Management Programme. Most samples displayed secular equilibrium between 238 U, 234 U, 230 Th and 226 Ra, indicating that there has been no significant radionuclide migration in these samples over periods as long as the last 1 Ma. Disequilibrium was observed in some altered near-surface and deeper fracture-filling mineral samples with 234 U deficiencies of up to 20%. A similar deficiency of 226 Ra was found at ∼ 1-km depth in a gypsum-infilled core sample. These results indicate that U and Ra leaching by groundwater has occurred within periods 1 Ma and 8 ka ago, respectively. One instance of 226 Ra excess was found at 94-m depth, indicating deposition of 226 Ra in the last 8 ka. All cases of disequilibrium involved fracture-infilling minerals or altered granite cores from fracture zones, indicating that radionuclide migration occurred via fractures. Examples were found, however, of altered samples or mineral infillings that showed no detectable disequilibrium. These locations have been closed to migration in the last 1 Ma. Relative age estimates are made for some of the infilling minerals, based on their U-series isotopic characteristics.

Theory of the Lattice Vibrations of Germanium

Abstract: Previous attempts to explain the frequency-wave number relations for the normal modes of germanium, which have been determined experimentally by Brockhouse & lyengar, have required the assumption of force constants between atoms which are relatively far apart. The theory then involves a large number of undetermined parameters which have no obvious physical justification, and the fact that the elastic constants of germanium satisfy an identity which might suggest that only interactions between adjacent atoms are important, has to be dismissed as a coincidence. In this paper we extend the Born-von K'armtan theory of lattice dynamics to apply to a simple model of the germanium crystal, in which each atom is regarded as a charged core coupled to an oppositely charged shell. This gives the atom the property of polarizability, not only in an electric field but also under the influence of bonding interactions between adjacent atoms. On the basis of this model, the frequency-wave number relations can be reasonably well accounted for with only two disposable parameters, and a simple explanation is provided of the fact that the elastic constants satisfy Born's identity. The value deduced for the polarizability of a germanium atom, using the neutron spectroscopy data of Brockhouse & Iyengar, is in good agreement with that determined directly from the dielectric constant. An extension of the theory of Mashkevich & Tolpygo provides some theoretical justification for the use of a shell model for germanium.

Gamma Radiolysis of Water Solutions Relevant to the Nuclear Fuel Waste Management Program

Abstract: The gamma radiolysis of water was investigated for conditions relevant to studies of the geological disposal of nuclear fuel waste. Chemical kinetic calculations were carried out for seven systems:...

An emergency bioassay method for actinides in urine.

Abstract: A rapid bioassay method has been developed for the sequential measurements of actinides in human urine samples. The method involves actinide separation from a urine matrix by co-precipitation with hydrous titanium oxide (HTiO), followed by anion exchange and extraction chromatography column purification, and final counting by alpha spectrometry after cerium fluoride micro-precipitation. The minimal detectable activities for the method were determined to be 20 mBq L(-1) or less for plutonium, uranium, americium and curium isotopes, with an 8-h sample turn-around time. Spike tests showed that this method would meet the requirements for actinide bioassay following a radiation emergency.