Showing papers by "Atomic Energy of Canada Limited published in 1985"

Plate Tectonics -- A Possible Controlling Mechanism in the Development of Hydrocarbon Traps in Southwestern Ontario

Abstract: Recent geological studies of southwestern Ontario and adjacent eastern segments of the St. Lawrence Platform strongly suggest that the succession of Paleozoic sedimentary and tectonic events recorded therein may have been triggered and controlled by plate motions and associated orogenic events centred at or beyond the margins of the craton. Tectonic forces operative in Appalachian, East Greenland, Innuitian and Cordilleran orogens evidently set in motion the epeirogenic processes that led to widespread submergence of the Canadian Shield, and to marine connection of the St. Lawrence, Hudson, Arctic and Interior platforms at periodic intervals of early to middle Paleozoic time. Some of the more intensive compressional stresses generated by plate motions rejuvenated selected basement segments to form prominent northeast, northwest and east-northeast trending arches parallel to the Appalachian. East Greenland and Innuitian orogens respectively. The positive response of some of the more intensively activated arch segments was probably in turn the triggering and controlling mechanism for the inception and progressive development of the Illinois, Michigan, Williston, Hudson Bay and other basins that formed in widely separated parts of the North American craton during Paleozoic time (Flawn, 1967; McCrossan and Porter, 1973). Reconstructions of Paleozoic depositional and tectonic processes along the eastern rim of the Michigan Basin in Ontario, and immediately adjacent regions of the Canadian Shield, supported by studies of satellite imagery, indicate that basement uplift during and subsequent to that time was transmitted through the crust by vertical rotation (tilting) of fault-bounded megablocks (Sanford et al., 1984). The fault-block readjustment that took place on and marginal to the Algonquin-Findlay arch trend in southwestern Ontario provided the structural control for the origin and development of Cambrian, Ordovician, Silurian and Devonian oil and gas traps. The reconstructions further indicate that all the fields discovered to date in Ontario (Beards et al., 1970) are directly or indirectly related to vertical fault-block movements that appear to be coincident with some of the major tectonic events recorded by Williams et al. (1972) and Herriksen and Higgins (1976) in the Appalachian and East Greenland orogens respectively. This finding has important application as an oil and gas exploration tool in southwestern Ontario. It may also have important application in basins elsewhere on the craton that may have been subjected to similar epeirogenic movements by compressional or extensional stresses of plate tectonic origin. LA TECTONIQUE DE PLAQUES -- MECANISME DE CONTROLE POSSIBLE DE L'EVOLUTION DES RESERVOIRS D'HYDROCARBURES DANS LE SUD-OUEST ONTARIEN RESUME Les etudes geologiques entreprises recemment dans le sud-ouest de l'Ontario et dans les secteurs est contigus de la plate-forme du Saint-Laurent portent a coire que la succession d'evenements sedimentaires et tectoniques paleozoiques qui s'y trouvent enregistres pourrait avoir ete provoquee et controlee par le mouvement des plaques et par les evenements orogeniques connexes centres en bordure ou au dela du craton. Les forces tectoniques qui ont agi dans les orogenes Innuitienne ont sans doute declenche les processus epirogeniques qui ont entraine la submersion, sur de vastes etendues, du Bouclier canadien, et ont periodiquement relie a l'ocean les plates-formes du Saint-Laurent, d'Hudson, de l'Arctique et de l'Interieur au cours du Paleozoique ancien a moyen. Certaines des plus intenses contraintes de compression engendrees par le mouvement des plaques ont provoque le rajeunissement de diverses parties du socle, de facon a former, parallelement a l'orogene des Appalaches, a l'orogene du Groenland oriental et a l'orogene Innuitienne, des arches proeminentes orientees nord-est, nord-ouest et est-nord-est respectivement. Le soulevement de certains des segments d'arche les plus actifs a vraisemblablement declenche la naissance et controle l'evolution progressive des bassins d'Illinois, de Michigan, de Williston, de la baie d'Hudson et d'autres qui se sont formes au cours du Paleozoique a des endroits largement espaces dans le craton nord americain (Flawn, 1967; McCrossan et Porter, 1973). La reconstitution des processus sedimentaires et tectoniques du Paleozoique le long de la marge est du bassin de Michigan en Ontario et dans les parties contigues du Bouclier canadien, ainsi que l'examen d'images prises par satellite, revele que le soulevement du socle qui s'est produit a cette epoque et apres a ete transmise par la rotation verticale (basculement) de gros blocs limites par des failles (Sandford et al., 1984). La rajustement des blocs failles, qui a eu lieu dans le sud-ouest de l'Ontario en bordure de l'arche d'Algonquin et d l'arche de Findlay et parallelement a ces structures, a fourni le controle structural necessaire a la formation et a l'evolution de pieges petroliferes et gaziferes au cours du Cambrien, de l'Ordovicien, du Silurien et du Devonien. La reconstitution indique egalement que tous les champs decouverts a ce jour en Ontario (Beards et al., 1970) sont directement ou indirectment lies aux mouvements verticaux des blocs failles qui semblent avoir ete concomitants a certains evenements tectoniques importants que Williams et al. (1972) et Herriksen et Higgins (1976) ont identifies dans les orogenes des Appalaches et du Groenland oriental respectivement. Cette decouverte represente un outil utile pour l'exploration petroliere et gaziere dans le sud-ouest de l'Ontario. Elle pourra egalement s'averer utile ailleurs dans le craton, dans les bassins qui ont peut-etre subi des mouvements epirogeniques similaires provoques par des contraintes de compression ou d'extension dues a la tectonique de plaques. 1 This paper summarizes a talk given by the writers at the annual meeting of The Ontario Petroleum Institute, London, Ontario, October 1983. Early drafts of the manuscript benefitted from critical reading by J.A. Wade, Atlantic Geoscience Centre, Geological Survey of Canada, Dartmouth, N.S. End_Page 52-------------------------

Effect of humic acid on uranium uptake by hematite particles

Abstract: The addition of humic acid to a hematite sol is shown to alter the uptake of uranium by the hematite particles. The magnitude of this alteration varies with the solution pH and the amount of humic acid added. Changes in uranium speciation, blocking of active surface sites, and extent of uranium-humic acid interactions are the dominant factors. Electrophoretic mobility data indicate that the surface charge of the particles becomes negative upon adsorption of humic acid, even at low humic acid concentration. The presence of uranium ions has little effect on this observation. Infrared spectroscopic analysis suggests that new bond formation may be involved in the uptake of humic acid or humic acid/uranium by hematite.

Energy loss spectrum of swift charged particles penetrating a layer of material

Abstract: The energy loss spectrum of a beam of charged particles penetrating a layer of random material has been analyzed theoretically. A steepest-descent evaluation of the Bothe-Landau integral yields general expressions for the spectrum, the most probable energy loss, and the halfwidth, without reference to a particular collision cross section. The procedure has been tested against rigorous results for model cross sections as well as the Landau-Vavilov theory for free-Coulomb scattering. The most probable energy loss is found to be systematically smaller than the mean energy loss by an amount which is independent of foil thickness for not-too-thin foils. This peak shift turns out to be insensitive to the angle of emergence from the foil but sensitive to nonuniformities in foil thickness and to detector resolution. The influence of shell corrections on the spectrum has been discussed, and the peak shift has been evaluated explicitly for the Landau-Vavilov case, for moderately relativistic ions, for slow ions stopped in a free electron gas, and for heavy ions stopped by elastic collisions. A procedure has been outlined for determining stopping power and straggling from measured peak energy losses and halfwidths. Systematic errors may be present in current stopping power data, caused by the use of most probable instead of mean energy loss values. Estimated peak shifts compare well with recent experimental results.

Lithium Isotope Separation: A Review of Possible Techniques

Abstract: Published methods for 6Li-7Li lithium isotope separation have been reviewed. Future demand for 6Li, whose main use will be as a tritium breeder in blankets surrounding the core of DT fusion power reactors, is likely to exceed 5 Mg/a in the next century. The applicability of the various available methods to such a large-scale production rate has been assessed. Research on improving the effectiveness of current lithium isotope separation processes has been carried out worldwide in several major areas during the past decade; these include two-phase chemical exchange systems, ion-exchange resin chromatography, and highly isotope-selective techniques like laser photoactivation and radiofrequency spectroscopy. Chemical exchange systems appear to offer good potential in the near term for 6Li enrichment, but efficient, laser-based methods could probably be developed for large-scale production by early in the next century.

Flammability Limits of Hydrogen-Oxygen-Diluent Mixtures:

Abstract: Flammability limits of hydrogen-oxygen-diluent mixtures were determined in a 5-cm diameter, 1.8-m long tube, for upward, downward and horizontal prop agation of the flame. It was found that for fuel-lean mixtures, upward limits were nearly independent of the diluent type and concentration; downward limits showed a slight dependence on diluent type and concentration. Limits for fuel- rich mixtures were independent of the direction of propagation of the flame. In all cases, to a good approximation, horizontal limits lay midway between the upward and downward limits. It was also found that limits for fuel-rich mixtures were dependent on the oxygen volume fraction. Empirical correlations are presented to estimate the limits.

A Logarithmic Detection System Suitable for a 4π Array

Abstract: A low pressure multiwire proportional counter, a Bragg curve counter, and an array of CaF2/plastic scintillator telescopes have been developed in a geometry suitable for close packing into a 4π detector designed to study nucleus-nucleus reactions at 100–200 MeV/nucleon. The multiwire counter is hexagonal in shape and gives X−Y position information using resistive charge division from nichrome-coated stretched polypropylene foils. The Bragg curve counter is a hexagonal pyramid with the charge taken from a Frisch gridded anode. A field shaping grid gives the Bragg curve counter a radial field. The scintillator telescopes are shaped as truncated triangular pyramids such that when stacked together they form a truncated hexagonal pyramid. The light signal of the CaF2-plastic combination is read with one phototube using a phoswich technique to separate the ΔE signal from the E signal. The entire system has been tested so far for particles with 1 ≦ Z ≦ 18 and gives good position, charge, and time resolution.

From Paper Drawings to Computer-Aided Design

Abstract: A Canadian feasibility study shows that the key to reliable and cost-effective automatic reading of drawings is detailed planning of an operator-assisted system.

From paper drawings to computer-aided design

Abstract: A Canadian feasibility study shows that the key to reliable and cost-effective automatic reading of drawings is detailed planning of an operator-assisted system.

Vibration of Tube Bundles Subjected to Two-Phase Cross-Flow

Abstract: Etude experimentale de la vibration de faisceaux triangulaires et carres de tubes dans des ecoulements croises de melanges d'air et d'eau

An Electrochemical Investigation of Localized Corrosion on Titanium in Chloride Environments

Abstract: Electrochemical methods have been used to study the crevice and pitting corrosion behavior of unalloyed titanium in chloride solutions at elevated temperatures (maximum 150 C). The investi...

Triggering of DNA strand breaks by 45 degrees C hyperthermia and its influence on the repair of gamma-radiation damage in human white blood cells.

Abstract: Human peripheral white blood cells, freshly isolated from normal individual donors, were exposed to hyperthermia. Heat-generated DNA strand break damage and white blood cell capacity to repair radiation-induced breaks were determined by a fluorometric alkaline unwinding assay. Strand breaks could be readily detected when white blood cells were incubated in a physiological salt solution at temperatures between 41 degrees and 46 degrees C, for times up to 90 min. The time course of strand break induction at 45 degrees C was characterized by a short initial lag, followed by a period of rapid break induction and subsequently a lower rate. Evidence is presented which suggests that the induction of DNA damage involved a "triggering" mechanism; a short treatment at 45 degrees C (10 to 20 min) initiated a cellular event which led to a rapid increase in the number of strand breaks during subsequent incubation of 37 degrees C. Continuous incubation at 45 degrees C produced less DNA damage than an initial period at 45 degrees C followed by incubation at 37 degrees C. This apparent "triggering phenomenon" was not due to a triggering of the respiratory burst in phagocytic cells, since no O2- could be detected; in fact, a 30-min treatment at 45 degrees C largely blocked the capacity of the cells to respond normally to a soluble stimulator of the respiratory burst. Unlike gamma-ray-induced breaks, 45 degrees C hyperthermia-induced breaks did not rejoin during subsequent incubation for up to 1 h at 37 degrees C. Additionally, 45 degrees C hyperthermia treatment progressively inhibited the ability of the cells to repair subsequent gamma-ray-induced breaks (4 Gy). This inhibition occurred during the period in which 45 degrees C heat rapidly induced strand breaks. Hyperthermia (41 degrees C), which did not trigger strand breaks, did not cause detectable inhibition of this repair capacity. There was no indication that hyperthermia sensitized cells to radiation-induced strand breaks.

Calibration of argon ion sputter rates using nuclear microanalysis and Auger spectroscopy

Abstract: Auger electron spectroscopy (AES), in conjunction with argon ion sputtering, is frequently used to obtain composition versus depth profiles. Thin film thicknesses may be estimated from such profiles if the argon ion sputtering rate of a particular material is known. For this work, a series of oxide standards was prepared and calibrated with nuclear microanalysis techniques. These standards were then used to calibrate the composition versus depth profiles obtained using AES.

Iodine chemistry in the +1 oxidation state. I. The electronic spectra of OI−, HOI, and H2OI+

Abstract: Electronic spectra are reported for the hypoiodite ion (OI−), hypoiodous acid (HOI), and its conjugate acid (H2OI+) in aqueous media. Iodine in the +1 oxidation state was produced by either of the ...

Radiation Processing Using Electron Linacs

Abstract: The performance capabilities of a modern linac make it a commercially viable tool for enterprising applied radiation chemists and biologists. Good economics requires efficient transformation of mains power to beam power and although pulsed travelling wave linacs have been used in industrial applications for several years, their high cost per watt is a disadvantage. The cw linac with its variants is a developed technology which could be used profitably in selected applications. More integrated designs like the self-excited linac and the induction linac also offer promise for the near future. Linac design optimization in relation to the physical and chemical processes desired in the irradiated product is discussed.

Energy-angle distribution measurements for 0.8v020Ne and 209Bi ions penetrating thin carbon foils

Abstract: Energy-angle distributions have been measured for 0.8v0, (v0 = Bohr velocity) Ne and Bi ions penetrating through carbon foils. Comparing the results with a Monte Carlo computer simulation that included an angle dependence only for the elastic collisions, we have observed for Ne projectiles an angle-dependent inelastic loss which, for small angles, is much larger than the elastic contribution in the case of thin foils. In the case of Bi, the energy loss distribution is dominated by elastic collisions. The calculations of Meyer, Klein and Wedell, and Ellmer and Wedell cannot describe the experimental results. The multiple scattering distributions are in agreement with both analytical and Monte Carlo calculations.

Recovery and packaging of tritium from Canadian heavy water reactors

Abstract: The Tritium Extraction Plant being built at Chalk River Nuclear Laboratories (CRNL) will be the first industrial scale demonstration of the Liquid Phase Catalytic Exchange (LPCE) process for transf...