The energetic characteristics of deuterium fueled fusion plasmas well below ignition and aided by neutral beam injection are investigated with the perspective of eventually being utilized in a fusion hybrid reactor. Particular emphasis is placed on the three modes of D-fusion cycles and on the role of the neutral beam ions as they effect the plasma ener-getics. Ion concentrations corresponding to steady state operation of the fusion cycles as well as total reaction rates and fusion gains are evaluated for regimes which tend to be identified with a two energy component reactor. The associated interrelation requirements on the temperature, density and magnetic confinement of the plasma are illustrated. It is shown how operational plasma constraints can be substantially relaxed by high energetic deuteron injection while retaining an energy viability sufficient for a synergetic fusion reac-tor concept.

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A theoretical analysis has been conducted to gain an insight into the effects brought on the non-equilibrium MHD gas properties and on the performance characteristics of a non-equilibrium MHD generator by the presence of impurities introduced into the potassium-seeded argon working gas from the fossil-fuel-fired heat exchanger adopted for heating the gas. Propane is envisaged as fuel, and as typical operating condition, the working gas is assumed to have a stagnation temperature of 2, 000 K, stagnation pressure of 5 atm, Mach ' number of unity, and seed fraction of 10-3. The gas enters a Faraday-type MHD generator with infinitely finely segmented electrodes operating at a loading factor of 0.75 in a magnetic field of 5 T subject to ionization instability. The results of computation reveal that the presence of impurities below certain limits in a range of roughly 10 to 100 ppm at the entrance of the generator (exact limit depending on the operation condition) will not pre-vent the MHD generator from operating at practically useful levels of power and current densities, and that the power level will not be unduly disturbed by fluctuations in the impurity concentrations if they are below the limits referred to above. The pumping work required for evacuation is found to be less than 1% of the total output power of a dual-cycle plant.

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The effects of toroidal magnetic field ripple on the energy loss of injected neutral beam ions have been investigated with Monte Carlo orbit-following calculations. For a high and flat density profile the loss of the energetic ions becomes high. It has been found that the loss becomes very high particularly towards the end of the heating phase when the plasma density reaches the value necessary for ignition.
In connection with tolerable field ripple the criteria for the choice of the number of TF coils and their size are discussed from the point of the plasma size and the space required for blanket, shield and maintenance. The reference reactor size studied is based on the recommended INTOR guiding parameters.

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Based on a heuristic approach, a practically applicable startup process for BWR's that minimizes the xenon transient effects has been derived, which answers this highly nonlinear complex multi-stage optimization problem, while satisfying the current constraints imposed for fuel integrity. The resulting PCP (Pre-Conditioning with Peripheral Rod Operation) method features an intermediate control rod pattern, with central region identical with the rated control rod pattern and with certain control rods fully inserted in the peripheral re. gion. This method has been successfully applied to the initial startup of a commercial BWR, and the expected performance was confirmed from operating data.

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Embrittlement of Zircaloy-4 cladding by oxidation of the inner surface occurring in an LWR loss-of-coolant accident was studied using simulated fuel containing of Al₂O₃ pellets sheathed in Zircaloy-4 specimen cladding, filled with Ar gas, and sealed. This simulated fuel rod was heated from outside until the isothermal oxidation temperature between 880 and 1, 167°C was obtained after the cladding burst. This exposed the inner surface of the cladding to the environmental atmosphere, provided by steam flowing at a constant rate in the range of 0.131.6 g/cm₂•min.
The embrittlement of the specimen due to inner surface oxidation is influenced primarily by the amount of hydrogen absorbed by the Zircaloy-4. Ring compression tests conducted at 100°C on test pieces constituted of sliced sections of oxidized specimen showed that Zircaloy containing more than 200300 wt.ppm of absorbed hydrogen became brittle when oxidized at temperatures above 1, 000°C. In the range of oxidation temperature 932 to 972°C, brittleness did not appear below 500-750 wt.ppm absorbed hydrogen.
Hydrogen absorbed by the Zircaloy precipitated in the form of fine hydride crystals formed along previous °-phase grain boundaries. Peaks were found in the distribution of hydrogen absorbed on the inner surface, at a distance of 1545 mm upward and downward of the rupture opening. Within this range, the distance was influenced by the oxidation temperature and steam flow rate.

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A simulation procedure of multicomponent separating cascades is developed. This pro-cedure is applicable and effective in such cases that the cut of mixture of each stage is prescribed and required to be independent of concentration, and the stage separation factors are given as input variables and very large. It can deal with cascades which have multiple feeds and sidestreams. The stage separation factors are allowed to be given as functions of compositions of down streams and up streams. The exact solutions are found out treat-ing all the basic equations simultaneously by use of multi-dimensional Newton-Raphson method.
As an application of this procedure to actual cascade calculations, a computer simula-tion study is carried out for hydrogen isotope separation system by porous membrane method which consists of two cascades and two catalytic equilibrators. It is proved that the Newton-Raphson iterative calculation proceeds stably under the assumed input and out-put conditions, and the porous membrane method is worth while to investigate in further studies as one of promising methods for hydrogen isotope separation.

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Natural background radiation in Japan was analyzed based on surveyed data which were rearranged from macroscopic points of view. The background levels were classified into seventeen groups from which a contour map was made by simple interpolations. The general pattern obtained showed that high levels are prominent in Hida Mountains-Wakasa Bay area and Joetsu-northern Kanto provinces, and low levels are prominent in Hokkaido and northern Tohoku districts along with Kanto Plain. The whole area was further divided into two classes according to whether the level is higher than the country-wide mean level. A boundary between the two classes seen in Chubu District was found almost exactly coincides with Itoigawa-Shizuoka Tectonic Line. Kanto Mountainland was found to have higher levels than its neighborhood, which supports the current idea that old geology of granitic rocks gives high level radiation. A good correspondence could be seen between the radiation contours and every tectonic line proposed as the eastern border of Fossa Magna which is important in the tectonics of Japan Islands. It was then anticipated that informations of the natural radiation will give valuable side evidences to infer the geologic history of Japan Islands.

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