A study has been made on the effects of differences in input wave forms on densities obtained by compaction with vibration exciter. The input patterns included sinusoidal, triangular, saw-tooth, inverted saw-tooth, square, cyclic pulse and inverted cyclic pulse-waves.
The highest density obtained for given acceleration was found to be with an input of saw-tooth wave at either 580 c/s or 800 c/s. As a general trend, the characteristics reported previously for the case of sinusoidal vibra-tion with respect to the influence of displacement and acceleration on the density obtained was found applicable to these other wave forms taken up this time.
The relationship, between frequency and density obtained was however found to vary widely, and this together with the surprisingly strong effect provided by the polarity of waves on compaction efficacy attests to the complexity of the effects of differences in wave form.

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Studies were made on the hydrolysis of uranium nitrides (UN and cubic U₂N₃) by super-heated steam. The resulting gaseous products were mainly hydrogen, though with U₂N₃ the hydrogen generation was replaced by that of nitrogen at higher temperatures. The condensed water contained ammonia, but not hydrazine. Both UN and U₂N₃ powders were ultimately con-verted to UO_2.1 after hydrolysis at temperatures up to 600°C; intermediate products (formed below 400°C) were presumably UO₂(N) or UN_1.7 in the case of UN and UN_1.8 with U₂N₃.
The reaction mechanisms corresponding to the formation of such chemical species were estimated mainly from the behavior of nitrogen and hydrogen evolution and from the yield of ammonia. The effect brought by N₂ atmosphere on the ammonia formation and on the dissolu-tion of nitrogen into solids were studied also by the hydrolysis under flowing N₂ gas. It was revealed that the yield of ammonia increased and the dissolution was inhibited by N₂ atmos-phere.

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The correction factor P(t) used in determining the fast fission effect of ²³⁸U was measured in the range of cooling time t= 30200 min for irradiations of 30 min, 2 and 5 hr, respectively. This factor depends quite sensitively on the bias level in γ-ray counting as well as on the irradiation time and cooling time after irradiation. It is emphasized that neglect of the depend-ence of P(t) on irradiation time and bias level results in a large error in measurements of fast fission effect of ²³⁸U.

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P'al-Bell's equation for the probability generating function of neutron counts has been analytically solved in the case of three time states, using two-forked approximation. From this solution it is found that all experimental data on neutron fluctuation consist individually of only three basic parameters. The average counting rate C, the decay constant a and the chain register rate C, are in this instance chosen for the three fundamental measures of correlation. The original observation is presented that Cr can be obtained precisely by determining the waiting time distribution for the triggering of the time analyzer.
The correlated and uncorrelated parts of the Rossi-α data in a thermal system have been analyzed by this three-parameter scheme, and a consistent explanation is given of the results obtained.

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A new formulation of the noise spectra in at-power reactors is presented. Input noise source is determined in such manner that ready comparison is possible between the square modulus of the reactor transfer function and the noise spectrum. The physical meanings of the noise-equi-valent source are clarified. A new noise source additional to that of zero-power reactors is found, which results in a non-white contribution to the input noise source spectrum.
The basis of the present theory is a set of macrostochastic variables characterizing the state of the reactor possesses Markoffian property. Three types of reactions are taken into account -source emission, linear and bilinear reactions.

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The equivalence relation between heterogeneous and homogeneous reactor systems was first established by Chernick & Vernon by using the rational approximation for the collision pro-babilities. The aim of this paper is to introduce refinements into the rational approximation. The parameters introduced are evaluated by separate considerations and are shown to be related to the Dancoff & Bell factors.
Throughout this work, narrow resonance considerations are invoked since partial neglect of scattering complicates the issue being studied.

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The separation factor (a) of Li-isotopes was determined by subjecting LiOH, Li-acetate, Li-citrate and Li-H.E.D.T.A. of various concentrations to ion exchange reactions with sulfonated polystyrene-D.V.B. copolymers of various degrees of cross-linking. With the view to accurate determination of a by enlarging the scale of experiment, frontal analysis in the column opera-tion was performed with exchange columns containing Dowex 50 W, X-12 and 16, or else Diaion SK, X-16 (X meaning crosslinkage of the exchanger). Experimental results revealed the a-values to be always higher with Li-acetate than with Li-hydroxide as eluant. Also Li-citrate eluants gave values somewhat lower than with Li-acetate system. Exchange systems with Dowex 50 W, X-12 and 16, with various concentrations of Li-acetate, yielded single stage isotopic separation factors ranging from 1.0025 to 1.0036. The corresponding value was 1.0027 for the system involving Dowex 50 W, X-16, 2050 mesh and 0.109 M solution of dilithium salt of N'- 2- (hydroxyethyl) ethylenediamine-NNN'-triacetic acid (H.E.D.T.A.).

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Uranium and Pu were extracted with tri-iso-octylamine (CCl₄) from irradiated U dissolved in sulfuric acid, from which Pu was back-extracted with sulfurous acid, and U with 1 1 M NH₄Ac-1.5%H₂O₂. The decontamination factors were estimated to be 10² for U fraction (γ and βactivities) and >10³ for Pu fraction.

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