[en] Numerical simulations and experimental studies have been made related to the possibility of employing an externally imposed electrostatic potential wave to separate isotopes. This wave/ion interaction is a sensitive function of the wave/ion difference velocity and for the appropriate wave amplitude and wave speed, a lighter faster isotope will be reflected by the wave to a higher energy while leaving heavier, slower isotopes virtually undisturbed in energy-allowing subsequent ion separation by simple energy discrimination. In these experiments, a set of some 200 individual electrodes, which surrounded a microamp beam of neon ions, was used to generate the wave. Measurements of the wave amplitudes needed for ion reflection and measurements of the final energies of those reflected ions are consistent with values expected from simple kinetic arguments and with the more detailed results of numeric simulations

[en] The sulfonic acid (SO₃H) group was readily introduced into a polyethylene (PE) membrane by radiation-induced cografting of sodium styrenesulfonate (SSS) with hydrophilic monomers such as acrylic acid (AAc) and hydroxyethyl methacrylate (HEMA). The density of SSS grafted onto the PE membrane was determined as a function of molar ratio of hydrophilic monomer to SSS in the monomer mixture. Immersion of the electron-beam-irradiated PE membrane into the mixture of SSS and HEMA for 5 h at 323 K provided to the SO₃H density of 2.5 mol/kg of the H-type product

[en] Experiments with Na¹³¹I in liquid phase were carried out at two feed rates to obtain the residence time distributions and to verify the invariance of the dimensionless residence time distribution in a rod mill grinding chromium ore. Based on the data the size-mass balance method was used to construct a simplified model assuming that the breakage and selection functions satisfy the standard hypothesis B(x,y)S(y)=axα. It was proved by simulation of a known size distribution that the model really works over practical operating ranges. Knowing the fact that the size interval of ground chromium ore between 0.08 and 1.2 mm gave the best concentration results on wet shaking tables, the model was used to predict the weight per cent of the desired size range in the ground ore versus various operating conditions. Recommendations are also given. (author) 14 refs. 6 figs

[en] Experiments of upflow- and downflow-forced turbulent and laminar convection, natural convection and buoyancy-assisted combined convection of water are performed in uniformly heated, square arrayed, nine-rod bundles having P/D ratios of 1.25, 1.38 and 1.5. The heat transfer data are correlated in the respective convective regimes, where the heated equivalent diameter is used as the characteristic length in all dimensionless quantities and water properties are evaluated at the mean bulk temperature. The forced convection data fall into two distinct regimes: forced turbulent and forced laminar; the Reynolds number at the transition between these regimes is a linear function of P/D. In the forced convection experiments the flow is hydrodynamically developing, but thermally fully developed. The natural convection data are correlated to within ± 10% in terms of Ra_q and the combined convection data are correlated to within ± 15% by superimposing the Nusselt numbers, raised to the fourth power, of forced laminar and natural convection. For all P/D values, the transition from forced laminar to combined convection occurs at Ri = 2.0. A comparison with triangularly arrayed rod bundles shows that for the same flow area per rod, the rod arrangement negligibly affects Nu in both forced and natural convection regimes. (author)

[en] We are attempting to establish scaling laws to simulate the mixing of helium (a simulant for hydrogen) with air in a large-scale enclosure by mixing salt water and fresh water, in a small-scale enclosure. This will allow us to assess the mixing of gases in a nuclear reactor containment using relatively small-scale liquid-mixing experiments. The scope of our current work does not cover the integrated effects of different mechanisms of gas mixing expected to prevail during postulated LOCA (loss-of-coolant accident) scenarios. The work is limited to mixing caused by jet inertia and buoyancy forces. Within this scope, we have identified the dominant scaling laws, and tested them by conducting gas-mixing experiments in a large-scale enclosure and liquid-mixing experiments in a small-scale enclosure. The experimental resutls demonstrate the validity of the scaling laws. (orig.)

[en] Two-phase flow models dominate the requirements of economic resources for the development and use of computer codes which serve to analyze thermohydraulic transients in nuclear power plants. An attempt is made to reduce the effort of analyzing reactor transients by combining purpose-oriented modelling with advanced computing techniques. Six principles are presented on mathematical modeling and the selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation in a simulation environment are demonstrated. It is explained that the drift-flux model is better suited than the two-fluid model for the analysis of two-phase flow in nuclear reactors, because of the latter's closure problems. The advantage of analytical over numerical integration is demonstrated. Modeling and programming techniques are presented which minimize the number of needed arithmetical and logical operations and thereby increase the simulation speed, while decreasing the cost. (orig.)

[en] The authors have been investigating the fundamentals of thermo-hydraulic instabilities which may occur during the start-up in natural circulation BWRs in order to establish a rational start-up procedure and reactor configuration. In this paper, geysering is investigated experimentally in two parallel channels in both natural and forced circulations under various conditions of heat input, inlet subcooling and non-heated riser length from the upper end of the heated section to the outlet plenum. The relationship between flow reversal and the onset of geysering is studied in particular. It makes clear that geysering in parallel boiling channels in natural circulation is fundamentally identical to that in forced circulation. Next, the effects of a large bubble covering the entire flow cross section and subcooling in the outlet plenum upon the occurrence of geysering are clarified. Finally, differences in behavior of geysering in a single channel as compared with that in parallel channels are discussed. (orig.)

[en] A macro-model composed of bar elements was proposed for applying to an elasto-plastic dynamic analysis for the three dimensional reinforced concrete shear wall. This macro-model enabled us to grasp the dynamic characteristics of shear walls by using a theoretical approach with the result of material tests. By using this macro-model, various kinds of consideration were made on the result of the pseudo dynamic tests described in the previous report, Part 1, and it was shown that the elasto-plastic response behaviors obtained by analysis agreed well with the test results, and thus the effectiveness of this model was confirmed. (author)

[en] Contact thermal conductance is much lower in a vacuum than normal pressure conditions. When one cools SR beamline optics, such as mirror components, a water cooled copper plate which is attached to the optics is used. In order to increase the effect on cooling, an indium sheet or liquid metal, such as Ga, In-Ga, is inserted between the optics and the plate. The authors experimentally obtained contact thermal conductance in a vacuum, which was essential to computing the thermal distribution of optics. And they simulated their cooling system using a beamline mirror component

[en] A method to measure the phases of synchrotron oscillation in a storage ring is proposed. It utilizes Pockels cells, which modulate the amplitudes of synchrotron radiation signals by two sinusoidal electric signals with inverse phases and send them to two optical-to-electric converters. A differential amplifier produces a difference in the resultant signals, which is proportional to the synchrotron phase over a certain range. Although the results depend on the bunch current, a similar electrooptic technique can be used to correct them. (author)