Abstract: A fuel compact formed by integrally molding coated fuel particles by a press into a cylindrical body and comprising a chamfer having plane or curved surface at its corner to thereby prevent the coated fuel particles from being damaged due to stress on press molding whereby the strength thereof is improved against mechanical contact with a fuel sleeve and a graphite block.

Abstract: Disclosed is a debris filter capable of reducing a pressure loss of coolant as it flows and capturing debris in the coolant. The debris filter includes bent plates, first plates, and second plates, all having respective same shapes, wherein each of the bent plates is composed of a first inclined strip-like plate and a second inclined strip-like plate. The bent plates are arranged parallel with each other, the bent plates and the first plates are fixed with each other so that the first plates intersect each first inclined plate, the bent plates and the second plates are fixed with each other so that the second plates intersect each second inclined plate, and the first plates does not touch the second plates.

Abstract: This invention provides a dripping nozzle device to produce ADU particles with good sphericity, a device for recovering a feedstock liquid to prepare a uniform feedstock liquid, a device for supplying a feedstock liquid to form drops with a uniform volume, a device for solidifying the surfaces of drops so that the drops will not deform easily when they fall onto and hit the surface of an aqueous ammonia solution, a device for circulating an aqueous ammonia solution so that the uranyl nitrate in the drops can be changed to ammonium diuranate completely, to such an extent that uranyl nitrate in the center of each drop is changed to ammonium diuranate, and an apparatus for producing ammonium diuranate particles with good sphericity. The dripping nozzle device is provided with a single vibrator to vibrate nozzles simultaneously. The device for recovering a feedstock liquid recovers the feedstock liquid remaining in the nozzles and mixes it with a fresh feedstock liquid.

Abstract: The object of the present invention is to provide a feedstock liquid, from which fuel kernels with good quality can be produced, and a method of preparing the feedstock liquid. The present invention provides a feedstock liquid with a viscosity from 4.0×10?2 to 6.5×10?2 Pa·s at 15° C., for the production of ammonium diuranate particles. The present invention also provides a method of preparing a feedstock liquid used for the production of ammonium diuranate particles, which includes mixing a uranyl nitrate solution and tetrahydrofurfuryl alcohol to produce a uranyl nitrate mixture, dissolving polyvinyl alcohol in water to produce an aqueous polyvinyl alcohol solution, mixing the aqueous polyvinyl alcohol solution with tetrahydrofurfuryl alcohol to produce a polyvinyl alcohol solution, and mixing the uranyl nitrate mixture with the polyvinyl alcohol solution.

Abstract: This invention relates to a MOX fuel assembly for PWRs that enables satisfactorily suppressing a power peaking factor without the necessity of reducing the Pu content per fuel assembly. The MOX fuel assembly has a lattice arrangement in which one or more burnable poison contained UO2 fuel rods and a plurality of MOX fuel rods are disposed in an n-rows by n-columns (n×n) lattice array. The MOX fuel rod consists of at least two kinds of MOX fuel rods including a plurality of first MOX fuel rods and a plurality of second MOX fuel rods. The first MOX fuel rod has a predetermined Pu content and a predetermined Pu weight, and the second MOX fuel rod has substantially the same Pu content as that of the first MOX fuel rod and a different Pu weight from that of the first MOX fuel rod.

Abstract: A fuel compact formed by integrally molding coated fuel particles by a press into a cylindrical body and comprising a chamfer having plane or curved surface at its corner to thereby prevent the coated fuel particles from being damaged due to stress on press molding whereby the strength thereof is improved against mechanical contact with a fuel sleeve and a graphite block.

Abstract: To furnish stably a sintered nuclear fuel compact of uranium dioxide with a large grain diameter, a fabrication method therefor requires sintering a starting material at two stages in an oxidizing atmosphere and in a reducing atmosphere at relatively low temperatures. The starting material is either a powder mixture of uranium dioxide fresh material powder and triuranium octaoxide in a weight ratio of 75/25 ˜ 55/45 or pulverulent mixed uranium oxides yielding a final O/U ratio equal to that of the powder mixture. The sintering process in the oxidizing atmosphere involves at least one time period of a temperature rise to a higher temperature of 1200 to 1100° C. and at least one time period of a temperature drop to a lower temperature of up to 1080° C. A temperature difference between the higher and lower temperatures is preferred to be 50° C. or more.

Abstract: The object of the present invention is to provide a material which takes on a color or which changes its colors when selectively sensitized by ionizing radiation (especially by low doses of radiation) and which is not sensitive to visible and ultraviolet light etc. This is achieved by microcapsules containing a radiation sensitive composition comprising leuco compounds (a) and organic halogen compounds (b) as indispensable components.

Abstract: A mixture of metal ions is added to the primary cooling water of a water-cooled nuclear reactor to inhibit deposition of radioactive materials in the cooling water on the inner surfaces of pipes. The mixture of metal ions added to the cooling water introduced into the primary cooling system simultaneously comprises two to four of the metal ions, Mn ion, Mg ion, Ni ion and Zn ion, one of these ions being manganese ion.

Abstract: A nuclear fuel assembly for use in a pressurized water reactor comprising a top nozzle and a bottom nozzle, fuel rods loaded and supported by grids in cells thereof and interconnected between a lowermost grid and the top nozzle, and a filter member interposed between the lowermost grid and the bottom nozzle.