No abstract available

[en] A dynamic model was set up to determine the fundamental frequencies of the BIPS. The model consists of a radiator which supports four discrete masses by means of interface structures. Various materials and several different sizes of interface structures were used in the analysis. The fundamental frequencies vary from 38 cps to 227 cps dependent upon the material and the size of interface structure. The built-in strength of all the interface structures are in excess of the 25 g's limit loading criteria

[en] A study of the oxygen vacancy disordering effects on the properties of high temperature superconducting YBaCu₃O_7-δ system is carried out. The degree of atomic order in the crystals is altered by quenching and annealing the sample at selected temperature for a certain amount of time. Superconducting transition temperature T_c depends on atomic ordering, it decreases after quenching, then increases with low temperature aging. The maximum observed variation of T_c (at fixed stoichiometry) is increased to about 27 K. The kinetics of atomic short-range ordering is systematically studied. It is found that the activation energies for oxygen diffusion in the basal plane are oxygen contents dependent. The different kinetics for samples with and without Au impurities is also studied. In addition to this, a change in the nature of the equilibrium state is observed at temperatures above a concentration dependent threshold temperature T*. The author associated T* with the phase boundary between the low temperature phase and the high temperature Ortho I phase. When samples are quenched from temperature above T* and subsequently annealed at temperatures around 51 degrees C, two relaxation processes with relaxation time constants differing by about two orders of magnitude are observed. The faster and slower relaxation processes are associated with changes in vacancy short-range disorder and the restoration of long-range chain vacancy order respectively. T* is determined for different oxygen concentrations and compared to theoretical phase diagram calculations

No abstract available

[en] The Canadian SCWR (supercritical water-cooled reactor), which operates at supercritical pressure and temperature, is being developed at AECL. It is required that flow and heat-transfer characteristics at supercritical conditions be investigated. The heat-transfer modes in supercritical fluids were studied using heat-transfer data from supercritical CO₂ flow. Entrance-affected, normal and deteriorated heat transfer were defined using CO₂ data from upward flow in an 8 mm diameter tube. The threshold value for normal heat transfer was defined using normal and deteriorated heat-transfer data. Normal and deteriorated heat transfer correlations were separately derived using the relevant data. The correlations developed include the effect of flow condition parameters on heat transfer for different heat-transfer modes. (author)

[en] A scheme is proposed for experimentally realizing the famous two-slit Gedaenken experiment using photons. As elegantly discussed for electrons by Feynman, a particle's quantum pathways interfere to produce fringes in the probability density for the particle to be found at a particle location. If the path taken by the particle is experimentally determined, the complementarity principle says that the fringes must disappear. To carry out this experiment with photons is difficult because normally the act of determining a photon's location destroys it. We propose to overcome this difficulty by putting a type-2 optical parametric amplifier (OPA) in each arm of a Mach-Zehnder interferometer, and observing fringes at the output. An OPA responds to an input photon by increasing its probability to produce a pair of photons with polarization orthogonal to the input, the detection of which allows partial inference about the path taken by the input photon without destroying it. Thus, the measurement is of the quantum nondemolition (QND) type

No abstract available

[en] The TFCX conceptual designs call for the construction of the reactor torus through the use of ''pie-shaped'' segments for mechanical and maintenance considerations. The use of this concept results in hot spots in the inboard section of the torodial field (TF) coils due to neutron and photon streaming through the slots between the segments. This work studies these effects on the nuclear responses in the TF coils and introduces design solutions to reduce the impact on the reactor design

[en] Design analyses and tradeoff studies for the bulk shield of the Tokamak Fusion Core Experiment (TFCX) were performed. Several shielding options were considered to lower the capital cost of the shielding system. Optimization analyses were carried out to reduce the nuclear responses in the TF coils and the dose equivalent in the reactor hall one day after shutdown. Two TFCX designs with different toroidal field (TF) coil configurations were considered during this work. The materials for the shield were selected based upon tradeoff studies and the results from the previous design studies. The main shielding materials are water, concrete, and steel balls (Fe1422 or Nitronic 33). Small amounts of boron carbide and lead are employed to reduce activation, nuclear heating in the TF coils, and dose equivalent after shutdown

[en] A shielding analysis for next generation of fusion devices (ETR/INTOR) was performed to study the dose equivalent outside the reactor building during operation including the contribution from neutrons and photons scattered back by collisions with air nuclei (skyshine component). Two different three-dimensional geometrical models for a tokamak fusion reactor based on INTOR design parameters were developed for this study. In the first geometrical model, the reactor geometry and the spatial distribution of the deuterium-tritium neutron source were simplified for a parametric survey. The second geometrical model employed an explicit representation of the toroidal geometry of the reactor chamber and the spatial distribution of the neutron source. The MCNP general Monte Carlo code for neutron and photon transport was used to perform all the calculations. The energy distribution of the neutron source was used explicitly in the calculations with ENDF/B-V data. The dose equivalent results were analyzed as a function of the concrete roof thickness of the reactor building and the location outside the reactor building