The gamma-ray spectrum emitted by present-day pine leaves reveals the presence of several peaks which do not belong to any naturally occurring nuclide. These peaks come from radioactive fission produts produced from nuclear weapon tests.
The gamma-ray spectra of pine leaves collected in 1958 and 1959 show two remarkable peaks. 0.13 MeV peak is actually a combination of peaks of ¹³¹Ce and ¹⁴⁴Ce-¹⁴⁴Pr, while 0.76 MeV peak is assigned as a peak of ⁹⁵Zr-⁹⁵Nb.
The decay curves of the gamma activity at 0.76 MeV correspond to curves of ⁹⁵Zr-⁹⁵Nb with half-life of 65 days. One gram pine leaves ash contains 26 mμc ⁹⁵Zr-⁹⁵Nb.

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Microstructure of outer and fractured surface of sintered uranium dioxide pellet was investigated using an electron microscope.
The technique of carbon atomic replica was adopted for the preparation of samples for electron microscopic observation. The structure of outer and fractured surfaces changes markedly, as expected, during the progress of sintering. Especially, the degree of sintering, sintering conditions and minute additives are sensitivelly and informatively reflected in the shape and microstructure of pores on fractured surfaces.
Pores in pellets well sintered in hydrogen are remarkably bounded by well developed facets, some of them show a perfect cubic holohedral symmetry. Their facets are indexed as {111}, {100}, {110} and higher indices nearly parallel to {110}. Facets indexed as {110} consist of repeated steps having much smaller facets {111}.
Contrary to the above, pores in pellets sintered in vacuo and in earlier stage pellets sintered in hydrogen show rounded and sometimes spherical shape. Crystalline anisotropy is supposed to be masked by strong surface migration or diffusion. Small facets bounded by concentric steps, however, are often observed on the wall of rounded and spherical pores. Their facets are indexed as {111}, {100} and {110}. Although Padden observed just {110}, it appears less frequently than others. Much smaller facets nearly parallel to {111} or {110} but slightly deflected to [100] directions are sometimes observed.
Small amounts of alumina or titania as additives affect differently to the shape of pores and the mode of precipitation on pore walls. The former tends to develop facets on pores, while the latter to keep the pores spherical.

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On account of radial spatial instabilities due to xenon and positive temperature effect, it is generally proposed that the several controllers must be set up separately in each region (sector) of the core cross-sectional area. Then it is convenient to express the control system by a matrix. Usually, because of the symmetric installation of the controllers, the system matrix is symmetric and cyclic, and it is easy to derive the unitary transformation, by which the characteristic equation of the system is invariant.
This paper describes a method of synthesizing feedback systems by plotting root locus. The application of this method to the Calder Hall type reactor is also presented here. The PACE A and B Analog Computer Units in JAERI is used to calculate the time behavior.

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In the present work, following items were studied about cold drawn uranium rods which had been β-treated.
(1) Relation between the thermal expansion coefficient in the drawing direction and the working degree (230% reduction in area)
(2) Change of the thermal expansion coefficient due to grain growth after recrystallization
(3) Thermal cycling growth of recrystallized specimens
From the above, the author tried to obtain what degree of working was allowable before the effect of the preferred orientation appeared, and also to observe the forming mechanism of preferred orientation by the measurement of the thermal expansion coefficient.
Following results were obtained.
(1) Preferred orientation was found even by only two per cent work, and the dimensional unstability was apparent on thermal cycling.
(2) As one component of preferred orientation, {010} pole was arranged parallel to the rod axis regardless of the degree of working.
(3) Grain growth after recrystallization affects the formation of the preferred orientation.

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The application of liquid metals to high temperature heat-transfer fluids has stimulated much development work on heat-transfer systems utilizing various low-melting and high boiling metals and alloys.
The selection of container materials to resist the attack by liquid metals is a difficult problem. The general way of attack by liquid corrodant is direct alloying, solution attack, intergranular penetration, corrosion by contaminants and others. Microscopic examination of metallographically polished surface was adopted to investigate the attack of liquid metals on iron and steels in the present study. The reliability of experimental method, the effect of oxygen and the effect of stabilizer of oxygen were examined.

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