Patent application number | Description | Published |
20130044850 | NUCLEAR REACTOR REFUELING METHODS AND APPARATUSES - Refueling of a nuclear reactor ( | 02-21-2013 |
20130202077 | Spacer Grid - A spacer grid includes interlocked straps comprising metal sheets or plates welded together to define a spacer grid having a top and bottom. The interlocked straps define a plurality of cells comprising vertical passages connecting the top and bottom of the spacer grid. The cells include: upper dimples proximate to the top of the spacer grid and distal from the mid-plane of the spacer grid; lower dimples proximate to the bottom of the spacer grid and distal from the mid-plane of the spacer grid; cantilevered upper springs having fuel rod engagement surfaces proximate to the top of the spacer grid and distal from the mid-plane of the spacer grid; and cantilevered lower springs having fuel rod engagement surfaces proximate to the bottom of the spacer grid and distal from the mid-plane of the spacer grid. | 08-08-2013 |
20130272464 | CONTROL ROD ASSEMBLY IMPACT LIMITER - A control rod assembly including at least one movable control rod including a neutron absorbing material, a control rod drive mechanism (CRDM) for controlling movement of the at least one control rod, and a coupling operatively connecting the at least one control rod and the CRDM. The coupling includes a terminal element engaged with a connecting rod of the CRDM and the at least one moveable control rod, and a kinetic energy absorbing element supported by the terminal element for absorbing kinetic energy during a SCRAM event, the kinetic energy absorbing element configured to act between the terminal element and an upper plate of an associated fuel assembly. | 10-17-2013 |
20130272477 | Pressurized Water Reactor with Skirted Lower End Fitting and Filter Plate - In a nuclear reactor core having fuel assemblies with upper and lower end fittings, a debris filter plate is attached to a lower end fitting having a skirt. The filter prevents debris from entering the fuel assembly, while the skirt prevents the trapped debris from sliding off the lower end fitting and continuing into the core. The lower end fitting is formed from a substantially square base and has flow channels to allow coolant to flow through it to the fuel assembly. The skirt is an extension of the metal of the lower end fitting that extends around the perimeter of the lower end fitting, spanning all four corners of the lower end fitting. In addition to capturing debris, the skirt also positions the filter, which may be manufactured from the same metal as the lower end fitting. | 10-17-2013 |
20130272480 | LOWER END FITTING LOCATING PINS - A nuclear reactor has a core installed on a lower core plate and formed from multiple fuel assemblies, each fuel assembly including a structural cage assembly. The structural cage assembly has an upper end fitting, mid grids, and a lower end fitting (LEF). The LEF positions the fuel assembly using four locating pins located at each corner of the LEF. The pins position the fuel assembly laterally by mating with receiving holes in the lower core plate. The locating pins have a chamfered tip with a flat end. The chamfered tip allows for a greater positioning margin when installing the fuel assembly in the core by guiding the pins into holes in the lower core plate, and the flat tip provides strength and stability in case the assembly is inadvertently rested on the tip of the pin instead of the LEF pads. | 10-17-2013 |
20130272481 | LOWER END FITTING LOCKNUT FOR NUCLEAR FUEL ASSEMBLY - A fuel assembly includes a plurality of fuel rods comprising fissile material, a plurality of guide tubes interspersed amongst the fuel rods, an upper end fitting connected with upper ends of guide tubes, and a lower end fitting. End plugs are connected with the lower ends of the guide tubes. The end plugs have threaded male shafts extending from the lower ends of the guide tubes which pass through openings of the lower end fitting. Female lock nuts are threaded onto the threaded male shafts of the end plugs and lock with the lower end fitting to secure the lower end fitting to the lower ends of the guide tubes. The female lock nuts suitably have locking portions that are outwardly deformed into recesses of the lower end fitting to lock the lock nuts in place after tightening. Dashpot tubes may be disposed in the lower ends of the guide tubes and connected to the end plugs. | 10-17-2013 |
20130301791 | PULSE ARC WELDING OF SPACER GRIDS TO GUIDE TUBES - A structural skeleton of a nuclear fuel assembly is assembled by inserting guide tubes through a plurality of spacer grids, and performing pulse arc welding to connect the inserted guide tubes and the spacer grids. In the structural skeleton, the spacer grids may comprise intersecting grid straps, and at least some of the grid straps may include tabs that are pulse arc welded to guide tubes. The structural skeleton may include grid retaining rings installed on the guide tubes and pinning some spacer grids, with the grid retaining rings being pulse arc welded to guide tubes. A fuel assembly includes the structural skeleton, a plurality of fuel rods comprising fissile material passing through the spacer grids, and upper and lower end fittings secured to upper and lower ends, respectively, of the guide tubes. | 11-14-2013 |
20140140463 | SMALL MODULAR REACTOR FUEL ASSEMBLY - A pressurized water reactor (PWR) comprises a pressure vessel containing primary coolant water. A nuclear reactor core is disposed in the pressure vessel and includes a plurality of fuel assemblies. Each fuel assembly includes a plurality of fuel rods containing a fissile material. A control system includes a plurality of control rod assemblies (CRA's). Each CRA is guided by a corresponding CRA guide structure. A support element is disposed above the CRA guide structures and supports the CRA guide structures. The pressure vessel may be cylindrical, and the support element may comprise a support plate having a circular periphery supported by the cylindrical pressure vessel. The CRA guide structures suitably hang downward from the support plate. The lower end of each CRA guide structure may include alignment features that engage corresponding alignment features of the upper end of the corresponding fuel assembly. | 05-22-2014 |
20140205053 | Spacer Grids With Springs Having Improved Robustness - A spacer grid includes intersecting straps defining cells with springs and dimples arranged to hold fuel rods passing through the cells. The springs are dual cantilevered springs with a bridge section between the distal end of the spring and the base. The distal portion of the spring is less stiff than the bridge section. The bridge section creates a bump which acts as a stop or travel limiter to prevent loss of grip force due to excessive spring deflection. | 07-24-2014 |
20140205055 | Spacer Grids For Nuclear Reactor - A spacer grid includes intersecting straps defining cells with springs and dimples arranged to hold fuel rods passing through the cells. The direction of the springs switches at a switch point in the spacer grid that is not at the center of the spacer grid. The intersecting straps may include a first set of mutually parallel straps including a first transition strap and a second set of mutually parallel straps including a second transition strap, with the second set intersecting the first set. The springs of the first set of mutually parallel straps face away from the first transition strap, and the springs of the second set of mutually parallel straps face away from the second transition strap. The outer straps in some embodiments include dimples but not springs. | 07-24-2014 |