Abstract: Example embodiments are directed to upper tie plates for debris mitigation and fuel bundles that use the upper tie plates. Example embodiment tie plates may include a plurality of debris capture elements that overlap each other so as to create debris traps for particulate debris that would fall onto the fuel bundle. Example embodiment fuel bundles may use the upper tie plates for debris mitigation.

Abstract: Systems and methods for servicing a fuel assembly in a light water reactor include those for controlling flow through a fuel assembly to maintain debris in the fuel assembly during removal and transportation of the fuel assembly, those for discharging debris from the fuel assembly, and those for isolating and sampling the water chemistry of a fuel assembly. An exemplary system includes a closure device configured to seal a mast to a fuel assembly to surround the upper opening of the fuel assembly and provide a flow control channel between a void in the mast and a lower opening in a lower tie plate.

Abstract: Example embodiments are directed to upper tie plates for debris mitigation and fuel bundles that use the upper tie plates. Example embodiment tie plates may include a plurality of debris capture features that overlap each other so as to create debris traps for particulate debris that would fall onto the fuel bundle. Example embodiment fuel bundles may use the upper tie plates for debris mitigation.

Abstract: A high pressure laser welding method and apparatus enables seam welding of a nuclear fuel rod at hyperbaric pressure. In an automatic process, a loaded fuel rod and an upper end plug are mated within a sealable weld box. A pressure within the weld box is controlled relative to a pressure within the fuel rod, and a laser assembly welds the seam at hyperbaric pressure. Helium flowing through a laser window nozzle during welding prevents soot contamination of the laser window glass and prevents formation of ionic plasma. The upper end plug fuel rod welding operation is thus reduced to a single step and eliminates inspection related tasks with respect to a sealed hole.

Abstract: A TIG welding system for controlling the weld shape for the seal welding of a small pressurization hole in the end plug of nuclear fuel rods. The controlled shape of the seal weld enables improved ultrasonic detection capabilities. The system achieves the desired weld shape by controlling the pressure differential between the interior and exterior volumes of the fuel rod. The weld box pressure is decreased in accordance with Boyle's law while the weld material for sealing the hole is molten. The system uses an output from the weld electronics as an input to a programmable logic controller ("PLC"). After a programmed time delay, the PLC outputs a signal to a solenoid valve to open a "ballast" volume. The expansion of gas from the weld box into the ballast volume causes a sudden drop in pressure to a level below the pressure inside the fuel rod. As a result of this pressure differential, the molten weld material forms a concave weld upon solidification.

Abstract: A TIG welding system for controlling the weld shape for the seal welding of a small pressurization hole in the end plug of nuclear fuel rods. The controlled shape of the seal weld enables improved ultrasonic detection capabilities. The system achieves the desired weld shape by controlling the pressure differential between the interior and exterior volumes of the fuel rod. The weld box pressure is decreased in accordance with Boyle's law while the weld material for sealing the hole is molten. The system uses an output from the weld electronics as an input to a programmable logic controller ("PLC"). After a programmed time delay, the PLC outputs a signal to a solenoid valve to open a "ballast" volume. The expansion of gas from the weld box into the ballast volume causes a sudden drop in pressure to a level below the pressure inside the fuel rod. As a result of this pressure differential, the molten weld material forms a concave weld upon solidification.