Abstract: A nuclear reactor facility including a primary containment vessel, a reactor pressure vessel installed in the primary containment vessel and accommodating a reactor core in a lower part thereof, and a vertical cylindrical wall disposed in a lower part of the primary containment vessel around and spaced from the reactor pressure vessel so as to delimit an annular space therebetween. The vertical cylindrical wall has an upper end disposed at a position higher than an upper end of the reactor core and a diaphragm extends substantially horizontally between the upper end of the vertical cylindrical wall and an inner wall of the primary containment vessel for cooperating with the vertical cylindrical wall to separate a space in the primary containment vessel around the reactor pressure vessel into a pressure suppression chamber and a drywell which includes annular space.

Abstract: A direct cycle type atomic power plant provided with a means for suppressing transfer of radioactive nitrogen compounds generated by nuclear reaction in the core from the reactor water to steam, where an increase in the dose rate in the main steam system and the turbine system due to carry-over of radioactive nitrogen atom, .sup.16 N, generated in the core can be suppressed, and the radioactivity therein can be reduced.

Abstract: A natural circulation type boiling light-water reactor comprises a pressure vessel, a reactor core disposed within said pressure vessel to heat light water so as to generate main steam, a steam outlet provided in a wall of said pressure vessel for drawing out the main steam therethrough to supply the same to a turbine system, and a steam path along which the main steam flows from the reactor core to the steam outlet. The reactor further comprises a steam guide for prolonging the steam path and/or a radially increased chimney for reducing the velocity of the main steam flowing through the steam path. These causes radioactive isotope .sup.16 N contained in the main steam to flow within the pressure vessel for a time period exceeding its own half-life, so that the inventory of .sup.16 N in the main steam directed towards the turbine system is reduced remarkably. In consequence, shield structures for piping and turbine systems can be reduced in size and weight.

Abstract: A container-outer-periphery pool in which water is stored is provided between a primary containment vessel and a reactor building, and outside of a pressure suppression pool. Consequently, the natural heat transfer capabilities of reactor facilities is enhanced, and the inherent safety of the reactor facilities is improved.

Abstract: A sheet-shaped molding material, comprising carrier films having therebetween a paste-like curable material including resin, filler, and reinforcing solid material of glass fiber. The elongation percentage of the carrier films is 1% lower with respect to the tension of 20 kg per m, to remove the curvature and bending of the material caused during the winding, and also to equalize the thickness of the material.

Abstract: Unsaturated polyester is produced by reacting dicarboxylic acid anhydride with alkylene oxide in the presence of a reaction product of dicarboxylic acid and dicyclopendadiene. The unsaturated polyester thus obtained gives a cured polyester resin having well balanced properties of mechanical strength and boiling-water resistance.

Abstract: At the time of starting up a nuclear reactor, the concentration of oxidizing substance in a cooling water in a reactor pressure vessel is decreased by evacuating the pressure vessel or replacing air in the vessel with an inert gas for a long time, below a predetermined level before the cooling water is heated to a temperature of 150.degree. C., thereby preventing the occurrence of stress corrosion cracking.