Abstract: The invention relates to compositions and methods for coating a zirconium alloy cladding of a fuel element for a nuclear water reactor. The coating includes a first tier or layer and a second tier or layer. The first layer includes an elemental metal and the second layer is an oxidation-resistant layer that includes elemental chromium. The first layer serves as an intermediate layer between the zirconium alloy substrate and the second layer. This intermediate layer can be effective to improve adhesion of the second layer to the zirconium alloy substrate. The multilayer coating forms a protective layer which provides improved capability for the zirconium alloy cladding to withstand normal and accident conditions to which it is exposed in the nuclear reactor.

Abstract: The invention relates to compositions and methods for coating a zirconium alloy cladding of a fuel element for a nuclear water reactor. The coating includes a first tier or layer and a second tier or layer. The first layer includes an elemental metal and the second layer is an oxidation-resistant layer that includes elemental chromium. The first layer serves as an intermediate layer between the zirconium alloy substrate and the second layer. This intermediate layer can be effective to improve adhesion of the second layer to the zirconium alloy substrate. The multilayer coating forms a protective layer which provides improved capability for the zirconium alloy cladding to withstand normal and accident conditions to which it is exposed in the nuclear reactor.

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: An advanced gray rod control assembly (GRCA) for a nuclear reactor. The GRCA provides controlled insertion of gray rod assemblies into the reactor, thereby controlling the rate of power produced by the reactor and providing reactivity control at full power. Each gray rod assembly includes an elongated tubular member, a primary neutron-absorber disposed within the tubular member said neutron-absorber comprising an absorber material, preferably tungsten, having a 2200 m/s neutron absorption microscopic capture cross-section of from 10 to 30 barns. An internal support tube can be positioned between the primary absorber and the tubular member as a secondary absorber to enhance neutron absorption, absorber depletion, assembly weight, and assembly heat transfer characteristics.

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.