[en] This paper provides detailed description of the characteristic MR appearance of delayed encephalopathy following acute carbon monoxide (CO) intoxication, with special emphasis on the distribution and pattern of white matter abnormalities. MR images of 17 patients (19-71 years old) with delayed encephalopathy of acute CO intoxication were retrospectively analyzed and correlated with clinical manifestations. The MR images were obtained on a 2.0-T superconducting unit during variable periods (3 weeks to 3 years) following the episode of acute CO intoxication

[en] A thermal stress analysis of the 300-MW(e) gas-cooled fast breeder reactor (GCFR) grid plate was performed to (1) assess the ligament stresses of the grid plate due to the thermal load generated by gamma heating from the reactor core, (2) determine the temperature-induced deflection of the grid plate and the resulting deformations of the core for reactivity changes and for space envelope effects on interfacing components, and (3) evaluate irradiation-induced swelling of the grid plate. A parallel study was conducted in which a theoretical method and a finite-element analysis were employed. The theoretical approach used a simplified model for the grid plate, and analyses were carried out using the concept of an equivalent solid material. The solid rim effect was added to account for the in-plane force generated by the rim due to a thermal expansion which was greater than that of the interior portion of the grid plate. The temperature in the grid plate varied in the axial and radial directions in an axisymmetric pattern. In the finite-element analysis, the perforated portion of the grid plate was treated as an equivalent solid plate with effective elastic constants, and at the outer rim the solid material properties were retained. Discrete temperature data were assigned at each mode of the finite-element model. The results of both approaches are discussed

[en] The Gas-Cooled Fast Breeder Reactor (GCFR) utilizes the concept of pressure-equalizing and venting fuel rods, primarily to avoid the possibility of cladding creep collapse due to high external coolant pressure (approx. 8.6 MPa). One of the major pressure equalization system development activities is a method for predicting the release and venting of gaseous fission products from the fissioning fuel rod. The gaseous fission product release rate is the rate at which gaseous fission products are released from the solid fuel matrix. The venting rate is the rate at which the released fission gases are vented from the fuel rod. Since some of the fission gas isotopes, such as xenon and krypton, are highly radioactive, the prediction of their release and venting rates is necessary for the design and analysis of the fission product trapping and storage systems. To this end, a considerable amount of information has been generated from irradiation experiments. In parallel with the empirical approach, an analytical model has been developed to permit the calculation of the isotopic fission gas release from the fuel of an operating fuel rod. The method consists of an isotopic fission gas release subroutine, GAREL, based on the diffusion of single gas atoms in a spherical fuel particle and a fuel rod thermomechanical performance analysis, LIFE-3. A summary of the GAREL analysis method and the calibration of the method using data from the GB-10 experiment is presented

[en] The primary function of the gas-cooled fast breeder reactor (GCFR) grid plate is to hold core assemblies firmly in position so that the reactivity insertion associated with the plate deflection is limited to a value which satisfies plant safety requirements. Consequently, grid plate deflection under pressure is of particular importance rather than stress, as in the case of most perforated plates. Analyses were carried out using the concept of an equivalent solid material, and the equivalent solid plate was treated as a transversely isotropic elastic body. The general solutions for the axial and radial displacements were derived for a simply supported plate subject to a uniform load. The solid rim effect was also included. Experimental and finite-element models were used to confirm the theoretical results, and it was found that the three solutions are in good agreement, and the maximum axial displacement discrepancy between them is about 6%. The close agreement of the three models not only proves that the analytical derivation and finite-element model are correct, but also indicates that the equivalent Young's modulus E* and equivalent Poisson's ratio V* are accurate

[en] The core support grid plate for the gas-cooled fast breeder reactor (GCFR) is a thick perforated plate into which the fuel assemblies are inserted and locked. The grid plate should be designed to be sufficiently rigid to minimize bending due to all expected service loadings which might splay the fuel assemblies apart, thus causing a reactivity change, albeit negative. In the present analysis, the equivalent solid material concept was used, and the equivalent solid plate was treated using a transversely isotropic elasticity theory. The general solution was derived for a simply supported plate subjected to a uniform load and included the solid outer rim effect

[en] A new modeling technique for the seismic analysis of the GCFR core support structure is under development. With the new technique one can determine what effect a large number of core elements, hanging as cantilevered beams from a perforated grid plate, have on the grid plate vibration. With this technique, the amplitudes and stresses of individual core elements can be computed. This method also permits the study, in a realistic manner, of the relative motions between the individual core elements. The analysis of the core support structure is divided into three steps: (1) Analysis of the grid plate; (2) Analysis of the core elements; and (3) Modal synthesis. The dynamic behavior of the grid plate and its influence on the seismic analysis is examined. The analysis of the fuel and blanket elements and the method of modal synthesis are also discussed. (auth)

[en] The report presents the results of a comprehenaive study of the effect of pressure loading on the gas-cooled fast breeder reactor (GCFR) core support structure. Two theories are investigated for the core support grid plate: thin plate theory and anisotropic elasticity theory. The case of an isotropic thick plate is also presented. The effect of transverse shear and normal stress in a thick plate and the effect of the outer solid rim of the perforated interior portion of the grid plate are studied. The grid plate support structure upper flange, support cylinder, and lower flange are analyzed, and the structural interaction between the grid plate and the support structure is discussed. Numerical results are presented for each analyss. The stresses obtained in the grid plate and the support structure are evaluated according to the requirements of the ASME Boiler and Pressure Vessel Code, Section III, Division 1, and the deflections of the grid plate are examined to determine whether the reactivity insertion limitation on the plant safety requirements is met. Since the final dimensions of the core support structure are not certain at this time, the report is not considered to be a final design stress report; however, it does examine the feasibility of the design and also demonstrates the analytical methods used to solve the grid plate problem from the standpoint of pressure loading

[en] The Isotope and Rare Atom Counting Equipment Facility, currently being constructed at the University of Toronto, is the result of over four years of experimental work on tandem accelerator based ultrasensitive mass spectrometry carried out by a collaboration of researchers from the University of Toronto, the University of Rochester, and General Ionex Corporation. This paper lists the basic design aims of the core of ISOTRACE - the Mass and Charge Spectroscopy System being built by General Ionex Corporation (GIC), and will outline the additions to this system which are under development locally

[en] For a long life photovoltaic cell the degradation of the device characteristics with 1 MeV electron radiation must be known so as to be able to predict the life of the cell. Hence, a study was made of radiation damage effects on the bulk properties of the silicon crystal, such as conductivity, Hall effect, carrier life time and carrier mobility. From the results of the data, it is concluded that there appeared to be a steady state damage level reached in P type material. (author)

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