Abstract: The invention relates to a multi-component cladding for a nuclear fuel rod that includes a combination of ceramic and metal components. More particularly, the invention is directed to a cladding that includes a ceramic composite having a zirconium composition deposited thereon to form a zirconium coated ceramic composite. The ceramic composite includes a ceramic matrix and a plurality of ceramic fibers. The cladding is effective to protect the contents of the cladding structure from exposure to high temperature environments during various load conditions of a nuclear reactor.

Abstract: A spring apparatus in accordance with the disclosed and claimed concept is usable in a nuclear installation. In one embodiment, the spring apparatus includes a plurality of springs that are in a compressed state and that are compressively engaged with an upper core plate of a nuclear reactor when the reactor is in a cold condition. However, when the reactor is in a hot condition, a spring of the plurality of springs is in a free state wherein a free end of the spring is in an uncompressed state and is disengaged from the upper core plate. In another embodiment, the spring apparatus employs a support apparatus that is also in accordance with the disclosed and claimed concept and that includes one or more bumpers that engage the springs of a spring pack from the underside.

Abstract: A method of detecting defects in nuclear fuel within a fuel rod that first heats the fuel rod to a temperature substantially above the ambient temperature. The surface temperature of the fuel rod cladding is then monitored as the fuel rod is allowed to cool. Variations in the temperature measured over the surface is then noted as an indication of defects.

Abstract: A nuclear fuel rod plenum spring assembly that has a spacer affixed to the lower end of the ground torsion spring. The spacer has a substantially flat surface on its underside that presses against the upper surface of the upper fuel pellets to spread the load of the spring over the top surface of the upper most fuel pellet.

Abstract: The present invention provides novel fuel assemblies for use with PWR nuclear reactors and power plants, and in particular, VVER nuclear reactors. The fuel assemblies offer enhanced structural stability, skeletal rigidity, and distortion (bow and twist) resistance to support high burn-up fuel management. Each fuel assembly may include a plurality of fuel rods, a plurality of control rods and guide thimbles, at least one instrumentation tube, and a plurality of grids. At least one fuel rod is replaced with a structural support replacement rod made from zirconium (Zr) alloy, stainless steel, or any other suitable material. The structural support replacement rod may be hollow or solid. The structural support replacement rods are preferably disposed at or about the periphery, and in some cases, the corners of the geometric array, which is preferably a hexagon or square.

Abstract: A method of detecting defects in nuclear fuel within a fuel rod that first heats the fuel rod to a temperature substantially above the ambient temperature. The surface temperature of the fuel rod cladding is then monitored as the fuel rod is allowed to cool. Variations in the temperature measured over the surface is then noted as an indication of defects.

Abstract: A nuclear fuel pellet design that is a cylindrical axial profile with either a larger radius or conical shaped ends such that the as built diameter at the ends of the pellet are slightly smaller than at the middle and at normal operating conditions, the diameter at the ends is nearly the same as at the middle. Preferably, there are short chamfers at the axial ends of the pellet.

Abstract: A nuclear fuel rod plenum spring assembly that has a spacer affixed to the lower end of the ground torsion spring. The spacer has a substantially flat surface on its underside that presses against the upper surface of the upper fuel pellets to spread the load of the spring over the top surface of the upper most fuel pellet.

Abstract: A debris filter bottom nozzle for a pressurized water nuclear reactor fuel assembly that employs a corrugated screen in combination with flow through holes in an adapter plate to filter out potentially damaging debris. The area between the screen and the adapter plate defines a plenum that forms a collection point for the debris and coolant access is provided to the plenum through openings in the screen and sidewalls of the nozzle.

Abstract: A nuclear fuel assembly having a tube-in-tube control rod guide tube design that incorporates an end plug that extends axially upward to an elevation above the lower most grid where it is sealed at its upper end to the lower end of the control rod guide tube. The guide tube lower end plug has a threaded recess in its upper surface that mates with a corresponding dashpot end plug threaded extension that is formed as an insert in the lower end of the guide tube. A hole formed through the outer wall of the guide tube end plug at the elevation of the lower portion of the recess provides a positive inspection port for assuring the proper seating of the dashpot. A method of manufacture of such a fuel assembly is also disclosed.

Abstract: A nuclear fuel assembly having a tube-in-tube control rod guide tube design that incorporates an end plug that extends axially upward to an elevation above the lower most grid where it is sealed at its upper end to the lower end of the control rod guide tube. The guide tube lower end plug has a threaded recess in its upper surface that mates with a corresponding dashpot end plug threaded extension that is formed as an insert in the lower end of the guide tube. A hole formed through the outer wall of the guide tube end plug at the elevation of the lower portion of the recess provides a positive inspection port for assuring the proper seating of the dashpot. A method of manufacture of such a fuel assembly is also disclosed.

Abstract: A nuclear fuel assembly having a tube-in-tube control rod guide tube design that incorporates an end plug that extends axially upward to an elevation above the lower most grid where it is sealed at its tipper end to the lower end of the control rod guide tube. The guide tube lower end plug has a threaded recess in its upper surface that mates with a corresponding dashpot end plug threaded extension that is formed as an insert in the lower end of the guide tube. A hole formed through the outer wall of the guide tube end plug at the elevation of the lower portion of the recess provides a positive inspection port for assuring the proper seating of the dashpot. A method of manufacture of such a fuel assembly is also disclosed.

Abstract: A nuclear fuel assembly having a tube-in-tube control rod guide tube design that incorporates an end plug that extends axially upward to an elevation above the lower most grid where it is sealed at its tipper end to the lower end of the control rod guide tube. The guide tube lower end plug has a threaded recess in its upper surface that mates with a corresponding dashpot end plug threaded extension that is formed as an insert in the lower end of the guide tube. A hole formed through the outer wall of the guide tube end plug at the elevation of the lower portion of the recess provides a positive inspection port for assuring the proper seating of the dashpot. A method of manufacture of such a fuel assembly is also disclosed.

Abstract: A nuclear fuel assembly having improved dimensional stability to support aggressive fuel management wherein the fuel skeleton lateral stiffness is enhanced by the addition of a second joint attachment between the control rod guide thimble and spacer grid support sleeve.

Abstract: The present invention provides novel fuel assemblies for use with PWR nuclear reactors and power plants, and in particular, VVER nuclear reactors. The fuel assemblies offer enhanced structural stability, skeletal rigidity, and distortion (bow and twist) resistance to support high burn-up fuel management. Each fuel assembly may include a plurality of fuel rods, a plurality of control rods and guide thimbles, at least one instrumentation tube, and a plurality of grids. At least one fuel rod is replaced with a structural support replacement rod made from zirconium (Zr) alloy, stainless steel, or any other suitable material. The structural support replacement rod may be hollow or solid. The structural support replacement rods are preferably disposed at or about the periphery, and in some cases, the corners of the geometric array, which is preferably a hexagon or square.

Abstract: In a nuclear reactor fuel assembly structured to support at least one non-linear fuel rod, the nuclear reactor fuel assembly includes at least two support grids, a first support grid and a second support grid structured to support at least one fuel rod in a non-linear shape. Each support grid has a plurality of generally square cells and wherein the cells on the first support grid and the second support grid are generally vertically aligned. Each cell has a first side, a second side, a third side, and a fourth side. Each cell further has protrusions extending from each the cell sides, wherein the protrusions are selected from the group including a spring, a dimple or an extended dimple. A spring is always disposed opposite of a dimple or an extended dimple. The first support grid includes at least one cell having an extended dimple extending from at least one cell side.

Abstract: A high energy absorption top nozzle for a nuclear fuel assembly that employs an elongated upper tubular housing and an elongated lower tubular housing slidable within the upper tubular housing. The upper and lower housings are biased away from each other by a plurality of longitudinally extending springs that are restrained by a longitudinally moveable piston whose upward travel is limited within the upper housing. The energy imparted to the nozzle by a control rod scram is mostly absorbed by the springs and the hydraulic affect of the piston within the nozzle.