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Showing papers by "Atomic Energy of Canada Limited published in 1979"


Journal ArticleDOI
TL;DR: In this article, high precision backscattering assemblies for absolute yield measurements have been built and calibrated to ± 1% on three different MeV ion accelerators, and the Bi-content in a set of Bi-implanted silicon standards (from the recent Karlsruhe ‘round-robin’ project) has been accurately measured in each of these assemblies: the resulting value is 477(± 0.07) × 1015 Bi atoms/cm2.

246 citations


Journal ArticleDOI
TL;DR: The adsorption of CO on Pt(111) has been studied by XPS, UPS, thermal desorption mass spectroscopy and by dynamic and static work function measurements at 95, 298, 377,403 and 453 K as mentioned in this paper.

228 citations


Journal ArticleDOI
TL;DR: In this article, a quantitative understanding of mirror Gamow-Teller transition in the nuclei was provided, considering core polarization, meson exchange, and relativistic corrections.
Abstract: Consideration of core polarization, meson exchange, and relativistic corrections gives a satisfactory, quantitative understanding of mirror Gamow-Teller $\ensuremath{\beta}$-transitions in $A=3, 15, 17, 39, \mathrm{and} 41$ nuclei.

139 citations


Journal ArticleDOI
TL;DR: In this paper, high-performance liquid chromatographic separations (< 20 min) of the lanthanides are illustrated for both 5- and 10-mu..m bonded-phase strong-acid ion exchangers.
Abstract: High-performance liquid chromatographic separations (< 20 min) of the lanthanides are illustrated for both 5- and 10-..mu..m bonded-phase strong-acid ion exchangers. The performance of these bonded phase packings is compared with that obtained with a 13-..mu..m styrene-divinylbenzene resin. The eluted metal ions are detected with a variable-wavelength detector after a post-column complexation reaction. The requirements and characteristics of post-column reaction for sensitive metal ion detection after separation on high-performance columns are discussed and the linearity, reproducibility, and sensitivity of the system used in the work are illustrated. The potential of on-column preconcentration for the ultratrace (pg/mL) determination of metal ions is also discussed and illustrated. 7 figures, 2 tables.

130 citations


Journal ArticleDOI
TL;DR: In this article, the velocity of hydride induced subcritical crack growth in Zr-2.5 pct Nb has been determined using the potential drop method for measuring crack extension.
Abstract: The velocity of hydride induced subcritical crack growth in Zr-2.5 pct Nb has been determined using the potential drop method for measuring crack extension. A revised picture of the two-stage, crack velocity-stress intensity relationship has been obtained with a threshold stress intensity of 6 MPa·m1/2, independent of temperature. A consistent temperature dependence of the crack velocity has been determined for hydrided material but the velocity measurements in as-received material are unexpectedly high. A previous theoretical model has been improved. The improved model has provided a useful basis for explaining some of the present data which could not be rationalized in terms of the previous model. Criteria for the stepwise crack propagation behavior are discussed.

120 citations


Journal ArticleDOI
TL;DR: In this article, the fracture toughness of hydride-containing zirconium alloys was investigated over the temperature range of 20 to 300°C on both hydrided Zr-2.5%Nb and hydrides of Zr 2.5%.

119 citations


Journal ArticleDOI
TL;DR: A theory of neutron diffraction in polycrystalline specimens of sulphur hexafluoride (SF6) and carbon tetrabromide (CBr4) was developed and applied in the interpretation of the neutron results as discussed by the authors.
Abstract: An investigation of the plastic phases of polycrystalline specimens of sulphur hexafluoride (SF6) and carbon tetrabromide (CBr4) by neutron elastic scattering and neutron diffraction experiments is reported. A theory of neutron diffraction in plastic crystals, which treats the Bragg scattering and the diffuse scattering from a unified point of view, is developed and applied in the interpretation of the neutron results. The Debye-Scherrer peaks are analysed, both by a cumulant expansion technique and a cubic harmonic analysis, to determine the crystal structures of the plastic phase which are found to be body-centred cubic (space group Im3m) for SF6 and face-centred cubic (space group Fm3m) for CBr4. The bond-orientation distribution function, f(Ω), has maxima in the directions for SF6 and in the directions for CBr4. Since, in both cases, f(Ω) is appreciably different from zero for all orientations, it is apparent that significant thermal reorientation takes place in both these crystals. The tr...

108 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived relationships between anisotropy of in-reactor creep and growth of zirconium alloys with their crystallographic texture and grain shape, and concluded that growth occurs primarily by partitioning of interstitials to dislocations or prismatic loops and vacancies to grain boundaries.

88 citations


Journal ArticleDOI
TL;DR: Data from G1-phase Chinese hamster cells in stirred suspensions containing various concentrations of DMSO could indicate the contribution of indirect action by hydroxyl radicals and hydrogen atoms to cell inactivation by single-hit and double-hit mechanisms for various radiation qualities.
Abstract: Populations of G1-phase Chinese hamster cells in stirred suspensions containing various concentrations of DMSO were irradiated with 250 kV X-rays or various heavy charged-particle beams. Chemical radioprotection of cell inactivation was observed for all LET values studied. When cell survival data were resolved into linear and quadratic components, the extent and concentration dependence of DMSO protection were found to be different for the two mechanisms. The chemical kinetics of radioprotection for single-events were similar for LET values up to those which gave the maximum RBE. DMSO protected to a lesser extent against energetic argon ions at an median LET of ∼ 220 keV/µm. These data could indicate the contribution of indirect action by hydroxyl radicals and hydrogen atoms to cell inactivation by single-hit and double-hit mechanisms for various radiation qualities. The decrease in RBE observed at very high LET may result, in part, from reduced yields of water radicals at 10−9−10−8 s resulting from radical recombination mechanisms within the charged particle tracks.

82 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructures of annealed zirconium, zircaloy-2 and Zr-2.5 wt% Nb containing α' were studied after neutron irradiation to fluences of ≈1 × 1025 n/m2, > 0.1 MeV, in the temperature range 573 to 923 K.

71 citations


Journal ArticleDOI
TL;DR: In this article, the authors show that proton and neutron configurations contribute about equally to the generation of angular momenta of two high-spin yrast isomers in $''144,146,147,148]-Gd$ whose detailed quasiparticle structure is suggested.
Abstract: Pulsed beams of $^{28}\mathrm{Si}$ and $^{4}\mathrm{He}$ were used to determine $g$ factors of eight isomeric states in $^{144,146,147,148}\mathrm{Gd}$ by the time-differential spin-rotation method. The results show that proton and neutron configurations contribute about equally to the generation of angular momenta of two high-spin yrast isomers in $^{146,147}\mathrm{Gd}$ ($I\ensuremath{\sim}19 \mathrm{and} \frac{49}{2}$) whose detailed quasiparticle structure is suggested.

Journal ArticleDOI
TL;DR: In this paper, the reaction sequences mackinawite → (greigite) → pyrrhotite (pyrrhhotite), and troilite → polygonal (polygonal) pyrhotite → pyramids of pyrite have been established by X-ray powder diffractometry.

Journal ArticleDOI
TL;DR: In this article, the steady state creep rate of as-received zircaloy-4 fuel cladding has been determined under constant uniaxial load conditions, assuming that creep rates can be described by a power law-Arrhenius equation.


Journal ArticleDOI
TL;DR: From the shape of the curve relating DNA size to percentage bound to hydroxyapatite, it is concluded that polypyrimidine .
Abstract: Polypyrimidine . polypurine segments are regions of duplex DNA which contain a highly asymmetric distribution of pyrimidine and purine nucleotides. A polypyrimidine in single-stranded DNA can be detected by its ability to form a complex and poly(A, G) which will bind to hydroxyapatite. We tested DNA from a variety of organisms and found that most contained polypyrimidines. From the shape of the curve relating DNA size to percentage bound to hydroxyapatite, we conclude that polypyrimidine . polypurine segments occur widely in DNA from higher organisms, at intervals of 6000--8000 base pairs throughout the majority of the genome. Lower levels occur in DNA from yeast and Drosophila.

Journal ArticleDOI
TL;DR: In this paper, a comprehensive spectroscopic investigation of yrast levels in three N = 126 isotones, 212Rn, 213Fr and 214Ra, is presented, where the authors report measurements of prompt and delayed excitation functions, γγ and X-γ coincidences, g-factors, linear polarizations and angular distributions of γ-rays.

Journal ArticleDOI
TL;DR: In this paper, the phase transition on a Pt(100) surface involves the lateral displacement of an entire plane of atoms, and it is further shown that the outward relaxation of the unreconstructed surface plane is negligible.

Journal ArticleDOI
TL;DR: In this paper, a quantitative correlation of the elongation and diametral rates of seven types of tubes with their texture, grain shape and dislocation density is developed assuming additive creep and growth components.

Journal ArticleDOI
TL;DR: In this article, the TNDCB was used for a fracture mechanics study of stress corrosion cracking (SCC) of cold worked Type-316 austenitic stainless steel exposed to hot aqueous solutions of 44.7 wt pct MgCl2.
Abstract: A new test specimen configuration, designated the T-notch double cantilever beam (TNDCB), was developed, calibrated and employed for a fracture mechanics study of stress corrosion cracking (SCC) of cold worked Type-316 austenitic stainless steel exposed to hot aqueous solutions of 44.7 wt pct MgCl2. The effects of stress intensity (K I ), temperature (T) and electrochemical potential (E) upon the crack velocity (v) and fractography were investigated. The stress intensity (K ISCC ) below whichv became immeasurably small was ∼12 MN·m−3/2. Above this value, three regions of behavior were observed. Region I exhibitedK I dependent cracking followed by Region II which exhibitedK I independent cracking and an apparent activation energy of 63 to 67 kJ/mol, followed by Region III where cracking again became dependent uponK I . The relative proportions of intergranular and transgranular crack paths were markedly dependent upon bothK I andE, and less sensitive toT. Crack velocity was insensitive to small changes inE with respect to the free corrosion potentials (E corr), but could be terminated by an applied active potential of ∼−0.35 VSCE. The pH within the propagating crack was estimated to be <1.0 atE corr, rising to ∼4.5 at −0.35 VSCE. The mechanism of SCC was discussed with respect to film rupture events caused by crack tip plastic deformation, adsorption controlled processes on the metal surface, and hydrogen diffusion in the metal lattice.

Journal ArticleDOI
TL;DR: In this paper, the dynamic behavior of flexible cylinders placed centrally within a narrow cylindrical flow channel were subjected to axial flow, both in liquid and in simulated two-phase flows; the effect of several parameters, such as the annular confinement, was investigated.
Abstract: Experiments are described in which flexible cylinders placed centrally within a narrow cylindrical flow channel were subjected to axial flow. The dynamic behavior of such cylinders, either cantilevered or supported at both ends, is described, both in liquid and in simulated two-phase flows; the effect of several parameters, such as the annular confinement, was investigated. It was observed that, with increasing flow, the cylinder is subject sequentially to instabilities of increasing mode number, confinement severely destabilizing the system. The experimental observations are compared to a theoretical model for the dynamics of such systems. In the case of liquid flow, agreement is qualitatively good and quantitatively fair - keeping in mind the experimental difficulties. In the case of two-phase flows, theory and experiment do not agree.

Journal ArticleDOI
TL;DR: The ELESIM code as mentioned in this paper models a single fuel element in a one-dimensional axisymmetric manner, and the constituent subroutines are physically based (rather than empirical) models, and include such phenomena as...
Abstract: The ELESIM code models a single fuel element in a one-dimensional axisymmetric manner. The constituent subroutines are physically based (rather than empirical) models, and include such phenomena as...

Journal ArticleDOI
TL;DR: In this paper, it is suggested that these dislocations are generated in order to maintain compatibility between crystallites which differ significantly in their ability to accommodate an imposed deformation by 〈a〉- slip.


Journal ArticleDOI
TL;DR: In this paper, the inverse reaction 24 Mg( 136 Xe, 4n) 156 Dy at 595 MeV has been used to populate high spin states in 156 Dy.

Patent
09 Apr 1979
TL;DR: Ozone treatment has been found very effective with alloys having surface metal oxides rendered more easily dissolved by ozone oxidation especially with chromium or chromium-nickel containing alloys as discussed by the authors.
Abstract: Heat transfer and associated surfaces in nuclear reactors are decontaminated by treating the surface with ozone to oxidize acid-insoluble metal oxides to a more soluble state, removing oxidized solubilized metal oxides, and removing other surface oxides using low concentrations of decontaminating reagents. Ozone treatment has been found very effective with alloys having surface metal oxides rendered more easily dissolved by ozone oxidation especially with chromium or chromium-nickel containing alloys.

Journal ArticleDOI
TL;DR: In this paper, diffraction-contrast features of individual damaged regions produced by low-fluence C+, N+ or Ar+ ions (0·5−2·0 MeV) were examined.
Abstract: The behaviour of the ordered alloy Zr3Al has been iavestigated by transmission electron microscopy following ion bombardments at temperatures ranging from 30 to 850 K. The diffraction-contrast features of individual damaged regions produced by low-fluence C+, N+ or Ar+ ions (0·5–2·0 MeV) were examined. Imaging with fundamental reflections revealed strain-contrast images arising from defect clusters which have essentially a spherically symmetrical strain-field and which presumably also encompass disordered regions. Other disordered regions, which were not associated with the defect clusters, were rendered visible due to structure factor contrast by imaging with 110 superlattice reflections. Both types of damaged regions were observed to anneal out in the region 723–848 K. With increasing bombarding ion fluence, Zr3Al gradually disordered and this transition was monitored by assessing the change in the long-range order parameter S. Post-irradiation annealing and high-temperature irradiation experim...

Journal ArticleDOI
TL;DR: In this article, the energies of alpha particles from radioactive sources were measured before and after transmission through thin, self-supporting films, and the preferred use of a monoenergetic alpha source such as 148 Gd was discussed.

Journal ArticleDOI
TL;DR: In this paper, a Doppler-broadened γ-ray lineshapes were determined for low-lying levels in 22 Ne, 28 Si and 31 P by bombarding 4 He implanted targets with beams of 19 F and 28 Si ions.

Journal ArticleDOI
01 Jun 1979
TL;DR: In this article, the focussed beam from a single line [P 1 (6)] pulsed HF laser has been used to decompose CH 3 OH (for pressures between 0.169 and 14.95 kPa) and isotopic mixtures of methanol.
Abstract: The focussed beam from a single line [P 1 (6)] pulsed HF laser has been used to decompose CH 3 OH (for pressures between 0.169 and 14.95 kPa) and isotopic mixtures of methanol. The normalized yields (number of product molecules Pulse/ P METHANOL ) of the non-condensable products H 2 , CO and CH 4 increased linearly with pressure (for the range ≈ 1 - 7 kPa). For sufficiently low pressures, selective excitation of one component of an isotopic mixture gives an isotopically enriched product. For example, selective excitation of CH 3 OH in equimolar of mixture CH 3 OH/CH 3 OD at a total pressure of 269 Pa gives hydrogen which is enriched 60-fold in H versus D. The degree of isotopic enrichment decreases with increasing mixture pressure. The efficiency of conversion of photon energy to reaction product has been observed to increase linearly with pressure. Decomposition studies have been performed in the presence of additives. These imply that the decomposition of methanol to H 2 involves mainly molecular rather than free radical steps.