The rates of reduction, hydrofluorination, fluorination and oxidation were measured for uranouranic oxides, U₃O₈ I, II and III, which was prepared from uranyl nitrate, ammonium diuranate and uranium peroxide, respectively.
In these reactions, U₃O₈ III was always the most reactive, U₃O₈ II was the next and U₃O₈ I was the least.
It is found that the rate of reduction of U₃O₈ with hydrogen can be expressed by (1-c)^1/3=1-kt where c is the molar fraction of uranous oxide and is the reaction time and k is the velocity constant. The constant is the best measure for the reactivity of U₃O₈.
The presence of nitrogen less than 0.05 wt% and other impurities such as iron, nickel, silicon and thorium in the oxide did not change the value of appriciably.

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In this experiment, a gravity sedimentation method like Andreasen pipette methodl for the determination of the particle size distribution of thorium oxide is used. The weighing method of Andreasen Pipette Method for the accumulative percentage of the particles is replaced with a γ-ray counting method. The sample material was activated by irradiation in JRR-1 or labelled with radioactive thorium-234 (UX₁). In both cases, the particle size distribution of thorium oxide in the range of 0.3μ, to 70μ was determined. The principle and discussion of this method and the application are also described.

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NaK is often used because of its particular suitability for high temperature heattransfer fluid, but the selection of structural materials for high temperature NaK system is somewhat limited.
From the results of static corrosion experiments, it has been found that the stainless steels of types 304, 316, 347 and ICN155 can be used successfully as container materials for NaK.
The present investigation was carried out to confirm the safety use of such materials under conditions of dynamic corrosion as well as to get informations on the technical difficulty in the manufacturing experimental NaK system.
This system was designed to operate up to approximately 600°C and type 347 stainless steel was used for piping.
Heat was supplied by electric heater and removed by air cooler. The regenerative heat-exchanger was provided to reduce the required power input and the pump used was the A-C Faraday type.
In this system, NaK was circulated at the rate of about 100g/sec.
The flow meter was D-C electromagnetic type. An expansion tank and a sump tank were also provided. “Resistance-type” and “lmpedance-type” level indicators were used successfully for the measurement of the level of NaK. The wetting of the pipe surface by NaK was found to affect both the heat transfer of heat-exchanger and the out-put voltage of the flowmeter.
This wetting can be attributed to the reduction of oxides on pipe surface and the precipitation of materials (oxide or others) from NaK on pipe surface.

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U-Mo alloy is of interest as power-reactor fuel. The purpose of this work was to study the characteristic behavior of the alloy when subjected to certain heat treatments as well as to get fundamental informations concerning its general properties.
The specimens were made by vacuum induction melting and were rolled at 600° and 900°C. In the heat treatment tests, the phase changes by quenching from various high temperature phases, the effects of quenching rate from gamma phase range, and Ms temperature for 1.30% Mo alloy were the subjects discussed.
Thermal cycling test revealed that greater improvement was obtained by gamma quenching followed by alpha annealing for the rolled rods with Mo content ranging from 0.5 to 9.0%. Oxidation test in air at 300°, 400° and 500°C had shown that the rate constant of oxidation decreased with increasing Mo contents in the lower Mo range, but it increased as Mo contents became higher. The same tendency was observed on the corrosion test in hot water. The minimum weight loss in 350°C hot water could be obtained at 12w/o Mo.

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For the purpose of using TPPC (Tetraphenylphosphonium Chloride) as an extraction reagent, uranyl ion was changed to the complex anion by benzoic acid. Tetraphenylphosphonium uranyl tribenzoate is extracted into chloroform layer from the buffer solution containing benzoic acid and sodium benzoate.
This paper described following subjects;
(1) Proportionality between polarographic diffusion current and uranium concentration
(2) lnterference of several ions on the extaction of uranium
(3) Effects of TPPC concentration on the percentage extraction of uranium and the ratio of uranium to TPPC
(4) lnvestigation of the optimum pH
(5) Effects of the concentration of the complexing agent on the percentage extraction of uranium
(6) Percentage extraction of Fission Products and the other raio active elements
The result gave a good method for the seperation of uranium with TPPC.

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[in Japanese]

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