Effects of the lead wire position along the resistive electrodes on the current distri-bution in a segmented Faraday-type MHD duct when the resistivity of electrodes is larger than the optimal one are investigated. Detailed two-dimensional calculations for current distributions for flat-shaped resistive electrodes indicate that the highly resistive flat electrode with a lead wire placed away from one end can give a substantially uniform current distribution and reduce the Hall electric field at the electrode-insulator interfaces. Also it is shown that the internal resistance due to resistive electrodes for relatively large Hall parameters may be still comparable with the internal resistance for conductive electrodes when the lead wire is shifted to the appropriate position on the resistive electrode.

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Numerical computations are made to estimate performance characteristics of resistive electrodes in a non-equilibrium Faraday type MHD generator duct. Potassium-seeded argon plasma at 1, 500 K, 10 atm is assumed. Two-dimensional computer simulations show that the use of resistive electrodes successfully reduces current concentration at the electrode edge and increases the effective electrical conductivity and the effective Hall parameter of the plasma. It follows that the equivalent conductivity derived from the internal resistance of duct including resistive electrodes is not so much smaller than for conductor electrodes, and their difference may be favorably influenced by reducing the electrode pitch and length. The paper emphasizes the mechanism of the streamer in the steady state, and illustrates the effect of resistivity of electrodes on the inclination of the streamer.

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A method of numerically integrating the Navier-Stokes equations is presented for axisymmetric compressible flows. A modified Newton's method is employed to determine the steady motion of gas in a rotating cylinder without the use of a time-consuming marching process with respect to time. A suitable form of the finite difference equations gives a computationally-stable integration with reasonable representation of the spatial characteristics of the flow. The method includes a Gaussian elimination procedure which consists of the transformation of the Jacobian matrix to a triangular matrix followed by the backward substitution. By using an auxiliary constant matrix algorithm, the method gives the solution within reasonably acceptable computation time.
As an example of the method, some features of solutions are presented for the steady flow of UF₆ gas in the centrifuges which have the openings for feed and withdrawal on the end plates.

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The separative power of a separating process is represented by the increase of the value of an isotope mixture which passes through the process. The separative power must be independent of the feed concentration, and is expressed by an arbitrary function of the heads and tails separation factors α and β, the functional form being chosen to suit practical convenience. This functional form is used to determine a value function, which is used for calculating the total separative power of an isotope separating cascade. When the constituent elements are asymmetric, different values are obtained for this separative power even if the cascade is operated under the same input and output con-ditions (i.e. flow rates and concentrations of feed, product and waste). In the present analysis, the functional form of the separative power is so determined as to minimize this dependence on asymmetry. When the feed concentration is very small compared with unity, as in the cases of heavy water production and uranium enrichment, the functional form to be adopted is δU=L{(α-1)βlnβ-(β-1)ln α}/(αβ-1), with which the dependence on asymmetry becomes almost negligible. On the other hand, when the feed concentration is nearly unity, the functional form agrees with that obtained by Bulang et al.: δUβ=L{(β-1)αlnα-(α-1)lnβ}/(αβ-1).

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The molecular dynamics method was applied to molten BeF2, in which the pair poten-tials of the Born-Mayer-Huggins type were employed. The Fourier transform of the dis-tances between a Be²⁺ ion and its nearest neighboring F^- ions averaged over total 128 Be²⁺ ions gave the frequency of about 175 cm-1 as the symmetric stretching frequency, which is in satisfactory agreement with 282 cm^-1 obtained with Raman spectroscopy.
The self-diffusion coefficients of Be²⁺ and F^- ions were estimated to be 2×10^-10 m² /sec and the internal energy was -2, 559 kJ/mol at 973 K.

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Thermoluminescent property of the mixture of CaSO4: Tm powder and non-luminous ⁶LiF powder was studied with a view to developing a personnel monitor for thermal neutrons. Its thermoluminescent response to thermal neutrons as a function of the particle size or the mixing ratio of both powders was investigated theoretically and experimentally. The phosphor sample, which was prepared according to the most favor-able conditions that the particle size of both powders was between 100450 μm and the mixing weight ratio of CaSO₄: Tm to ⁶LiF was 1 : 1, was found to have the following dosimetric properties.
(1) The thermoluminescence output is linear against neutron dose in a dose range from 10 μrem up to 6 rem.
(2) The thermoluminescent efficiency remains constant even after 5, 000 repetitions of exposure-reading-annealing procedure.
(3) A thermal neutron dose of 1 mrem can be determined with a standard deviation of 5.2% even under a γ-ray background of 10 mR.

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Experiments have been performed at JRR-4 (Japan Research Reactor) to investigate the capability of neutron radiographic techniques in applying to the nondestructive in-spection of UO₂-PuO₂ mixed-oxide fuels. The object of the inspection was to detect "Pu particles" in the mixed-oxide fuels. In place of the actual fuel, two stages of TiO₂- Eu2O3 mixed-oxide fuel dummy samples (the 1st stage for preliminary experiments and the 2nd stage for simulating the ATR fuel) werefabricated and radiographed with the direct exposure method using a Gd converter screen and high resolution films.
Neutron radiographs of the 1st stage dummy samples showed the excellent capability of the detection technique. Those of the 2nd stage dummy samples, however, revealed the detection limit of the technique, which showed that the present technique had not enough capability to satisfy the requirements in the inspection and that improvements of the detection technique especially on the contrast should be accomplished.

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