摘要:
In a boiling water reactor fuel bundle, a three dimensional debris catching grid construction is placed within the flow volume defined by the lower tie plate assembly between the inlet nozzle and upper fuel rod supporting grid. A perforated plate is utilized having round holes as small consistent with the prevention of inadvertent closure due crudding and a hole pitch consistent with mechanical integrity requirements. The perforated plate is placed in a three dimensional construction such as a dome, cylinder, pyramid, inverted pyramid or corrugated construction spanning the flow volume of the lower tie plate assembly. As a consequence of this three dimensional grid construction, the total flow through area of the perforations in the metal plate does not introduce appreciable pressure drop in the lower tie plate assembly between the inlet nozzle and the rod supporting grid. Fluid movement at the debris restraining holes of the grid construction has a low flow velocity and a change in flow direction before passing through the holes to discourage debris from finding its way through the grid holes. Finally, it is possible to incorporate debris traps within the flow volume of the lower tie plate assembly that can cause trapping and subsequent removal of trapped debris upon fuel bundle replacement. A double corrugated plate having large holes in the lower plate and smaller holes in the upper plate is utilized to trap debris.
摘要:
In a boiling water reactor fuel bundle, a three dimensional debris catching grid construction is placed within the flow volume defined by the lower tie plate assembly between the inlet nozzle and upper fuel rod supporting grid. A perforated plate is utilized having round holes as small consistent with the prevention of inadvertent closure due crudding and a hole pitch consistent with mechanical integrity requirements. The perforated plate is placed in a three dimensional construction such as a dome, cylinder, pyramid, inverted pyramid or corrugated construction spanning the flow volume of the lower tie plate assembly. As a consequence of this three dimensional grid construction, the total flow through area of the perforations in the metal plate does not introduce appreciable pressure drop in the lower tie plate assembly between the inlet nozzle and the rod supporting grid. Fluid movement at the debris restraining holes of the grid construction has a low flow velocity and a change in flow direction before passing through the holes to discourage debris from finding its way through the grid holes. Finally, it is possible to incorporate debris traps within the flow volume of the lower tie plate assembly that can cause trapping and subsequent removal of trapped debris upon fuel bundle replacement.
摘要:
In a nuclear reactor fuel assembly, a relatively flexible mounting member for mounting a large coolant conducting tube to the lower tie plate whereby excessive side forces on the fuel rod spacers are avoided in the event of lateral displacement of the fuel assembly such as during a seismic event.
摘要:
A control rod includes four panels in cruciform section each containing a plurality of absorber tubes. The absorber tubes are mounted between upper and lower mounting structures having generally T-shaped slots opening toward one another. The absorber tubes have generally T-shaped end plugs for reception in the slots. The slots and end plugs are configured to permit limited axial movement of each absorber tube relative to the control rod and to adjacent tubes. The absorber tubes are maintained in tension during all nuclear operations including during a scram.
摘要:
In a nuclear fuel rod assembly including a plurality of fuel rods and at least one water rod held together in a bundle, and wherein end plugs at the lower ends of the fuel rods and the at least one water rod engage a lower tie plate, an improvement wherein the end plug at the lower end of the at least one water rod is hollow and includes a multi-diameter flow metering bore for regulating coolant flow into the water rod.
摘要:
A latch pin assembly is configured to enable selective engagement with at least one of the fuel assembly channel and the coolant rod such that the fuel assembly channel and the coolant rod can be selectively utilized to support the fuel assembly load, thereby eliminating the need for fuel tie rods. The latch pin assembly includes a latch pin selectively engageable with the fuel assembly channel and the coolant rod, and an anchoring assembly cooperating with the latch pin, wherein the anchoring assembly anchors the latch pin in a selected position such that the latch pin engages at least one of the fuel assembly channel and the coolant rod. The latch pin may be alternatively engageable with the fuel assembly channel and the coolant rod or simultaneously engageable with the fuel assembly channel and the coolant rod. With this arrangement, the bail handle can be used both to remove the entire assembly including the fuel assembly channel from the reactor vessel or to remove only the fuel bundle from the reactor vessel, leaving the fuel assembly channel in place.
摘要:
A fuel assembly for a nuclear reactor vessel includes a plurality of fuel rods, at least one coolant rod, a lower tie plate supporting the fuel rods and coolant rod, and a channel surrounding the fuel rods, coolant rod and tie plate. The lower tie plate is supported by the channel such that the channel carries a load of the fuel assembly. In one aspect of the invention, a conventional upper tie plate is removed and a handle assembly is provided that includes two spring loaded latch pins engageable with corresponding apertures in the channel. A transition member supports the lower tie plate and is rigidly secured to the channel. Thus, when lifting the fuel assembly from the reactor, the channel bears the load of the fuel assembly. If it is desired to remove the fuel bundle from the channel, the handle assembly is released from the assembly by releasing the latch pins. The bundle can then be removed from the channel by attaching a grapple head to the coolant rod ends, which are specially shaped to facilitate an attachment tool.
摘要:
A fuel assembly for a nuclear reactor vessel includes a plurality of fuel rods, at least one coolant rod, a lower tie plate supporting the fuel rods and coolant rod, and a channel surrounding the fuel rods, coolant rod and tie plate. The lower tie plate is supported by the channel such that the channel carries a load of the fuel assembly. In one aspect of the invention, an upper tie plate includes two spring loaded latch pins engageable with corresponding apertures in the channel. A transition member supports the lower tie plate and is rigidly secured to the channel. Thus, when lifting the fuel assembly from the reactor, the channel bears the load of the fuel assembly. End gussets or clips are welded to the channel and inserted into the transition member, which serve as a secondary support for the transition member in the event that its primary connection to the channel fails. A channel guide member is secured to the, upper tie plate and includes two ears that are received in ear apertures in the channel. The channel guide and ears thus provide a redundant attachment between the tie plate and the channel in the event that the spring loaded latch pins fail. If it is desired to remove the fuel bundle from the channel, the upper tie plate is released from the assembly by detaching the guide member and releasing the spring loaded latch pins. The bundle can then be removed from the channel by attaching a grapple head to the coolant rod ends, which are specially shaped to facilitate an attachment tool.
摘要:
In a fuel bundle assembly for a nuclear reactor wherein a plurality of fuel rods and tie rods extend between upper and lower tie plates and wherein some of the fuel rods are partial length fuel rods extending between the lower tie plate and a spacer located between the upper and lower tie plates, an improved end plug is provided for at least each of the partial length fuel rods, each end plug secured between a respective partial length fuel rod and the lower tie plate. The end plug includes an upper portion constructed of a first alloy material and including an exterior fuel rod receiving surface and a tapped hole in a lower end thereof, and a lower portion constructed of a second alloy material and including upper and lower threaded sections, the upper threaded section receivable within the tapped hole and the lower threaded section receivable within a tapped hole in the lower tie plate. The threaded end plug may be used with full length fuel rods as well as bundle tie rods. A related method of removing the fuel rod with the improved end plug from the lower tie plate is also disclosed.
摘要:
A fuel bundle assembly for a nuclear reactor includes a lower tie plate; a transition piece underlying the lower tie plate; a plurality of fuel rods and at least one water rod seated on the lower tie plate and extending in substantially parallel relationship toward an upper end of the fuel bundle assembly, wherein a fuel bundle assembly lifting load is carried by load bearing members including certain of the fuel rods or by the at least one water rod; a plurality of spacers axially spaced along the at least one water rod and including means for laterally supporting each of the fuel rods; and a handle bar assembly at the upper end of the fuel bundle assembly connected to the load bearing members such that the plurality of non-load bearing fuel rods are supported only by the lower tie plate and the plurality of spacers.