Specific surface area was measured on swaged UO₂ compacts by B.E.T. method using Kr as adsorbate. The procedure for specimen preparation of swaged UO₂ compact is discussed in the report. Measured values of cold swaged UO₂ compact (88% T.D.) were mostly 0.51-0.70 m²/g, while those of hot swaged UO₂ compact (94% T.D.) mostly 0.05-3.13m²/g.

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Fused salt electrolysis obtaining uranium dioxide has been demonstrated to be applicable to uranyl fluoride resulting from the hydrolysis of uranium hexafluoride. The potential-pO^2- (negative logarithm of the activity of O^2- ion) diagram was referred for guidance in electrowinning of UO₂ from fused halides. Acceptors of O^2- ion were found to produce good melts with sufficient dryness for obtaining sound UO₂. Polarograms of uranyl reduction showed that uranium oxide would exist in the form of UO₂ as an intermediate species at low concentrations of UO₂(VI). Carbon anodes in molten solution containing UO₂(VI) would act as UO₂ electrodes prior to the electrolysis, so that low cell voltages such as 0.05V were sufficient at low current densities. Crystalline UO₂ particles produced in an electrolytic pilot unit with a capacity of 1kg oxide had a density of up to 10.75g/cm³ and total impurities were less than 0.1%.

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Aluminum, iron(II), copper, and molybdenum 8-quinolinol complexes, chromium (II) and manganese 8-hydroxyquinaldine complexes and nickel dimethylglyoxime complex can be quantitatively extracted into chloroform from large volumes of aqueous phases adjusted to an approriate pH for each metal. These metals can be determined by measuring the absorbance of the organic phases containing their complexes at an appropriate wavelength for each metal. By the proposed method, quantities exceeding 3p.p.b. of aluminum, chromium, and manganese, and 5p.p.b. of copper, iron, molybdenum and nickel can be determined when a 500 ml sample of water is available.

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Some critical examinations on the studies reported in the three previous articles are made.
(1) The collecting efficiency of the airborne sampler used for sampling radioactive debris at high altitude is considered to be 100%.
(2) The indication of the anemometer used for measuring air volume is purely volumetric and does not depend on the state of sir.
(3) Explosion date*, of nuclear weapons are calculated from the collected samples by the formula
A(t)=-A₁t^-1.2
This formula bolds well when "t" is small, but samples taken more than 50 days after explosion do not yield good results.
(4) Time-dependent variations of the concentrations of radioactive debris sampled above the isles of Hokkaido, Chubu and Kyushu districts are studied. The study reveals that a turbulent diffusion mixing process must prevail in the meridional air flow mechanism in the lower stratosphere.

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The detection limit and the precision of dose estimation by photographic dosimetry were statistically analysed. The detection limit of Fuji Badge Film was found to be 9 mR for Ra γ-rays, and stack densitometry with three films improved the limit down to 5.6mR.
It was found that the precision of dose estimation below 30mR was mainly dependent on the variances of the film background density.
Latent image fading was found to cause no change in the standard deviation of the optical density.
Accordingly, the effect of fading on the detection limit and the precision of dose estimation could be treated as if the sensitivity of the film had been reduced by a factor equal that of the fading.
Discussion is presented on the relationship of the detection limit to the standard deviation of the background density and to the film sensitivity. The ratio of the background density standard deviation to the film sensitivity was found to be closely related with the detection limit of the film.
The probability of detecting a positive dose beyond the variance of the background density was calculated for the case where the film was replaced every 3 months. Ten miliroentgen of γ-exposure can be detected in every film at a confidence level of 95%.

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A procedure for the direct numerical integration of the transport equation in slab geometry is introduced. The angular flux is expressed as a series of Legendre polynomials. The iteration process is utilized for the spatial integration of the transport equation. Prior to applying this method both to neutrons and to photons, a series of studies on the photon penetration problem has been performed to assess its validity. The first code, the EOS_1, was prepared for the NEAC 2206 computer to perform the above mentioned work and also to solve some practical problems of not very large scale.
A comparison of energy buildup factors obtained by the EOS_1 code with those from the moments method and from the Monte Carlo method indicates that the method presented in this paper provides a correct treatment of the attenuation of radiations in a slab. The results also agree well with the energy spectra from the moments method, with the energy spectrum measured in the Bulk Shielding Reactor and with the energy-angular flux distributions obtained with ⁶⁰Co and ¹³⁷Cs sources behind iron and aluminum plates, both with respect to spectrum pattern and to absolute values.

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