Abstract: The invention relates to a method for producing actinium-225 and bismuth-213. According to the invention, radium-226 is irradiated in the thermal neutron flux of a nuclear reactor, the thorium fraction of the irradiation product is then chemically isolated and therefrom the actinium and radium mixture growing continuously by decay therein is chemically separated, this mixture serving as "cow" for the desired radionuclides which are growing continuously.

Abstract: A core of a light-water reactor comprises a plurality of fuel assemblies each including a number of fuel rods. The fuel rod is provided with at least one area interposed between fuel areas in a clad of the fuel rod. The interposed area contains extremely reduced or substantially no fissile nuclide. At least two areas or layers with high enrichment of the fissile nuclide are formed in the axial direction of the reactor by the location of the interposed areas throughout the whole fuel assemblies arranged in the light-water reactor core.

Abstract: A rectilinear sectioned water rod--preferably of square cross-section--is provided with horizontal grooves for keying to bands on the inner, water rod surrounding aperture of spacers. Each spacer is constructed preferably of Inconel and includes a specialized inner band for keying to the water rod. The inner spacer member includes an upper surrounding band, a lower surrounding band, and four connecting vertical members--one positioned at each corner of the water rod. Two adjacent vertical members are bent inward to contact one side of the water rod at spaced apart points on the corners of the water rod. The remaining two adjacent vertical members are bent inward to contact the remaining two corners at single points on each vertical member.

Abstract: A system and process for the production of nitrogen-13 ammonium ions from a target material in the form of a dilute solution of ethanol in natural water by the reaction of protons with oxygen-16 within the target material. The system includes a device for producing a proton beam which travels along a preselected path and strikes the target material in a target chamber. This target chamber is positioned in the path of the proton beam such that subjection of the target material to the beam produces nitrogen-13 atoms in a predetermined form. These nitrogen-13 atoms are converted in the aqueous solution to ammonium, ions and oxides and are conducted from the target holder to a purification device for collecting a purified product containing such ammonium ions. A cooling system serves to dissipate heat generated during the production of the nitrogen-13 atoms by the reaction of protons with the oxygen. Other solutes for the target material are discussed.

Abstract: In a boiling water nuclear reactor fuel bundle, a debris catching arrangement is disclosed for incorporation within the flow plenum up stream or below the rod supporting grid of the lower tie plate assembly. The device is preferably placed within the lower tie plate flow plenum between the fuel bundle inlet orifice and the rod supporting grid structure supporting the fuel rods; alternate placement can include any inlet channel upstream of the fuel rods including the fuel support casting. Paired plates defining offset holes and bosses are utilized. The bosses are supported at plate webbing between the respective holes. The holes are preferably square in plan with appropriately relieved and rounded corners defining the edges of the webbing. The bosses may be cylindrical, square or rectangular in cross-section. In confrontation of plates to form the debris catching grid, each boss from one plate confronts a hole from the remaining plate.

Abstract: A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

Abstract: A pneumatic safety system for a nuclear reactor includes a containment vessel containing He.sub.3 at high pressure communicating with a nuclear core by way of a conduit system which includes hollow pipes situated adjacent rods of fissionable material inside the core area. A rupturable diaphragm is interposed in the conduit system and is connected by a plurality of heat-pipes to the core area. The heatpipes respond to changes in core temperature and at a critical temperature cause the diaphragm to rupture thus allowing neutron absorbing gas under high pressure to quickly flood the core shutting down the nuclear reaction.

Abstract: A method and an apparatus for locking the tie rods to block rotation relative to either the upper or lower tie plates utilizing the required fuel bundle channel. A conventional lock nut is provided for threading to the upper threaded end of the tie rods. This lock nut has attached extending wings, these wings when rotated interfering with a placed fuel bundle channel. In installation to the fuel bundle, and assuming that the tie rod has been fully threaded to the lower tie plate, the winged lock nut is rotated overlying the upper tie plate to cause full engagement of the upper tie plate to the tie rods. In such fastening, the winged lock nuts are rotated to an angle that provides no interference with the subsequently placed channel. Thereafter, and when the channel is placed, the channel interference with the rotational path of the wings of the lock nut and thus prevents relative rotation between the tie rod and winged lock nut.

Abstract: A method in which a surface layer material whose amount of reduction is to be measured is activated to find a distribution ratio of two or more kinds of radioactive nuclides that are produced in the space in the surface layer of the material, and the distribution ratio is used as an index for the amount of reduction of surface layer material. The amount of reduction in the surface layer material is measured in situ, nondestructively, easily and irrespectively of obstacles and the distance that exist between the detector and the material that is to be measured.

Abstract: A Cu--Sn based sintered material, which has an improved corrosion-resistance, is provided by setting the Pb content at 1 to less than 10% and adding from 0.1 to 30% of a hard matter(s) selected from the groups (a), (b), (c) and (d). The hard matter is(a) Fe.sub.2 P, Fe.sub.3 P, FeB, Fe.sub.2 B and Mo.(b) Fe--Cr, Fe--Mn, Fe--Ni, Fe--Si, Fe--W, Fe--Mo, Fe--V, Fe--Ti, Fe--Nb, CuP, Cr, and W;(c) SiC, TiC, WC, B.sub.4 C, TiN, cubic BN, Si.sub.3 N.sub.4, SiO.sub.2, ZrO.sub.2, and Al.sub.2 O.sub.3 ;(d) Si--Mn, Cu--Si, and FeS.Most of said hard matter being dispersed in Cu particles, grain boundaries between Cu particles, and between the Cu and Pb particles.

Abstract: Upper internals for a nuclear reactor comprise an upper core plate and a plate which supports cluster guides tubes connecting the two plates together. The cluster guides project above the support plate. A bottom wall of the support plate is situated at a level just higher than the outlet nozzles of the reactor vessel and each guide is supported by the bottom wall of the support plate by abutment of a shoulder formed in a passage of the bottom wall, in the lower half thereof.