Abstract: The present invention provides a gray rod control assembly for a nuclear reactor. The gray rod control assembly includes a spider assembly having a plurality of radial extending flukes and a plurality of gray rod assemblies coupled to the flukes of the spider assembly. Each of the gray rod assemblies includes an elongated tubular member, a first end plug, a second end plug, and a neutron absorber. The neutron absorber includes a matrix of refractory metal fabricated to be porous into which a metal or metal alloy is infused. The neutron absorber is distributed among a plurality of the gray rod assemblies.

Abstract: The present invention provides a gray rod control assembly for a nuclear reactor. The gray rod control assembly includes a spider assembly having a plurality of radial extending flukes and a plurality of gray rod assemblies coupled to the flukes of the spider assembly. Each of the gray rod assemblies includes an elongated tubular member, a first end plug, a second end plug, and a neutron absorber. The neutron absorber includes a matrix of refractory metal fabricated to be porous into which a metal or metal alloy is infused. The neutron absorber is distributed among a plurality of the gray rod assemblies.

Abstract: The present invention provides a gray rod control assembly (GRCA) containing an improved neutron absorber comprised of a porous matrix of refractory metal infused with a neutron absorbing metal or metal alloy for a nuclear reactor. The reactor has a plurality of fuel assemblies, each including numerous elongated fuel rods supported in an organized array by substantially transverse support grids, and a plurality of guide thimbles disposed through the support grids and along the fuel rods. The GRCA includes a spider assembly structured to provide controlled insertion of gray rod assemblies within the thimbles of the fuel assembly, thereby controlling the rate of power produced by the reactor. Each gray rod assembly includes an elongated tubular member, a first end plug, a second end plug and the improved neutron-absorber disposed within the tubular member.

Abstract: The present invention provides a gray rod control assembly (GRCA) containing an improved neutron absorber comprised of a porous matrix of refractory metal infused with a neutron absorbing metal or metal alloy for a nuclear reactor. The reactor has a plurality of fuel assemblies, each including numerous elongated fuel rods supported in an organized array by substantially transverse support grids, and a plurality of guide thimbles disposed through the support grids and along the fuel rods. The GRCA includes a spider assembly structured to provide controlled insertion of gray rod assemblies within the thimbles of the fuel assembly, thereby controlling the rate of power produced by the reactor. Each gray rod assembly includes an elongated tubular member, a first end plug, a second end plug and the improved neutron-absorber disposed within the tubular member.

Abstract: A nuclear fuel assembly having a parallel array of elongated fuel elements supported between an upper and lower nozzle. Main support grids are substantially evenly spaced along the elongated dimension of the assembly to maintain the spacing between fuel elements. A plurality of auxiliary vibration-resistant grids respectively positioned between the main support grids in the middle third elongated dimension of the fuel elements, that are smaller in height and provide a larger fuel element contact area than the main support grids.

Abstract: Nuclear fuel rod tubes of zirconium alloy are heat treated in an induction furnace to produce a protective oxide coating two to fifteen microns in thickness. The furnace is only slightly larger than the tubes and receives the endmost eight inches of the tube. The furnace is controllable in zones along the tube. To calibrate the furnace to produce the desired temperature profile, typically a flat profile at a temperature between 650.degree. and 750.degree. C..+-.1.5.degree. C., a temperature calibration probe is provided with spaced thermocouples for sensing the temperature developed in the probe at each of the zones when heated. The probe is made of inconel 600 stainless or the like, and is dimensioned and shaped to correspond closely to the dimensions of the fuel rod tubes, including having a closed chamfered end. At the opposite end the probe protrudes from the furnace, where the thermocouple leads are terminated. The leads pass through a potting compound in the probe, such as magnesium oxide.

Abstract: In a method for nondestructive measurement of the heat affected zone of an identification code on a nuclear fuel rod tube, the change in impedance of an electromagnetic coil produced by a portion of the tube to be etched with a bar code is measured before and after the etching of the bar code is performed by use of laser power. The impedance change in the coil produced by the bar code-bearing tube portion is compared with the impedance change produced in the coil by the same tube portion before the bar code is generated thereon to determine whether a maximum allowed depth of the heat affected zone of the tube portion has been exceeded.

Abstract: In a nuclear fuel rod identification system, a bar code etched directly on a surface of a nuclear fuel rod is read by first positioning the fuel rod such that its surface portion having the bar code etched directly thereon, such as by a laser, is disposed adjacent to a light diffuser surface and between such surface and a light reader. Next, a beam of laser light is directed on the bar code on fuel rod surface portion such that the light is reflected therefrom onto the light diffuser surface. Then, the light reflected from the bar code via the light diffuser surface is received and read by the light reader. The light diffuser surface is disposed at about thirty degrees relative to the path of the beam of light directed to the fuel surface portion such that only about twenty-five percent of the light is reflected by the diffuser surface back to the light reader.

Abstract: In a nuclear fuel rod identification system, indicia is provided on a nuclear fuel rod in two stages. In the first stage, by use of a laser beam a bar code is applied directly on the fuel rod cladding tube prior to loading it with nuclear fuel and attaching plugs to opposite ends thereof to provide an assembled fuel rod. In the second stage, after loading nuclear fuel into and attaching end plugs to opposite ends of the fuel rod cladding tube with the applied bar code to provide an assembled fuel rod, by use of a laser beam, identification and enrichment symbologies are applied respectively to the side and end of one of the end plugs of the assembled fuel rod.