Induced nuclear reactions: processes – systems – and elements – Handling of fission reactor component structure within... – Fuel component
Reexamination Certificate
2000-04-12
2001-10-30
Behrend, Harvey E. (Department: 3641)
Induced nuclear reactions: processes, systems, and elements
Handling of fission reactor component structure within...
Fuel component
C376S260000, C376S446000
Reexamination Certificate
active
06310930
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus and methods for guiding a nuclear fuel bundle into a channel and particularly relates to apparatus and methods for guiding a fuel bundle having a plurality of nuclear fuel rods, water rods and a plurality of spacers into a fuel bundle channel through an open upper end of the channel.
In the fabrication of fuel bundle assemblies for boiling water nuclear reactors, it is customary to lower the fuel bundle channel onto the fuel bundle. The fuel bundle comprises an array of nuclear fuel rods and one or more water rods with spacers at axially spaced positions along the fuel bundle. The channel comprises essentially an elongated rectilinear sleeve which, in assembly with the fuel bundle, engages the outer margins of the spacers. This conventional procedure for lowering the channel about the fuel bundle is practical in part because the channel weighs a small percentage of the overall weight of the fuel bundle, e.g., 50 to 60 pounds, and can be easily guided manually onto the bundle with minimum risk of damage to any of the fuel assembly components.
In certain fuel bundle assemblies, however, mechanical support for the fuel assembly is provided solely by a channel transition assembly and the bundle upper tie plate. The channel transition assembly typically consists of the channel attached at its bottom to a transition nose piece. The nose piece is dimensionally very similar to the dimensions of the outside of a lower tie plate but it does not have the lower grid plate that holds the fuel rod and water rod lower end plugs. Because the nose piece in the channel transition assembly is pre-attached to the channel, the conventional assembly procedure noted above cannot be used and the procedure must be reversed, i.e., the bundle must be lowered down into the channel. This substantially increases the risk of damage to fuel bundle components, especially to the fuel spacers, since the heavier weight of the bundle, e.g., 600 pounds, renders manual control of the position of the bundle more difficult while the fuel bundle is being lowered into the channel. The lowermost spacers of the fuel bundle are especially susceptible to damage during this procedure if the bundle and channel are misaligned relative to one another by as little as a tenth of an inch.
BRIEF SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention, apparatus and methods are provided for guiding a nuclear fuel bundle into a channel to form the fuel bundle assembly. Particularly, a guide apparatus is attached to the top of the channel to align the fuel bundle and channel one with the other as the fuel bundle is lowered into the open upper end of the channel. The guide assembly, in a preferred embodiment, comprises upper and lower guide plates spaced one from the other, with each guide plate having an opening for registration with the opening at one end of the channel and sized to receive the bundle through the opening. The lower guide plate opening is dimensioned to correspond to the internal wall dimensions of the channel. Location corners and slides (shims) depend from the lower guide plate and engage about the upper end of the channel to locate the opening through the lower guide plate in accurate registration with the opening through the channel.
The upper guide plate is spaced above the lower guide plate by a plurality of structural support members which preferably diverge one from the other in a direction toward the upper guide plate. The opening through the upper guide plate is slightly larger, for example, on the order of ⅞-inch wider, than the opening through the lower guide plate. Mounted on top of the upper guide plate are a plurality of rollers, preferably four, located to engage the corners of the spacers of the fuel bundle as the fuel bundle is lowered through the upper guide plate opening. The four corner rollers on the upper guide plate are dimensioned to correspond to the interior dimensions of the channel corners, as well as the spacer comers. Thus, the rollers make contact with the comers of the fuel bundle spacers as the spacers pass beyond the rollers, providing with the lower guide plate opening and channel a second alignment point for the fuel bundle. The corner rollers are also located at a height above the lower guide plate which corresponds to the spacing between the first and second fuel spacers of the fuel bundles. This assures that the first spacer is properly aligned as it enters the channel. Additional spring-biased sets of rollers may be provided along the structural members between the rollers fixtured on the upper guide plate and the bottom guide plate to engage the fuel rods at corners of the bundle as the fuel bundle is lowered into the channel. The spring-biased sets of rollers are displaced outwardly against their spring bias when the next spacer arrives at that elevation during the guided insertion procedure.
Additionally, visual alignment indicators are carried by the first and second guide plates to provide visual indication of any misalignment of the fuel bundle and channel. The indicators provide a visual alignment guide to ensure that there is no tilt of the fuel bundle relative to the channel. Once the fuel bundle has been lowered through the guide apparatus and into the channel, the guide apparatus can be lifted off the top of the channel. The use of this guide assembly permits the installation of the fuel bundles into the channels, both in the pool at the nuclear reactor site, as well as during fabrication of the fuel bundle assembly.
In a preferred embodiment according to the present invention, there is provided apparatus for guiding a nuclear fuel bundle having a plurality of fuel rods, at least one water rod and a plurality of spacers for insertion into a fuel bundle channel having an opening at one end thereof, comprising a guide assembly having first and second guide members spaced from and in registration with one another, the first guide member having an opening for registration with the opening at one end of the channel sized to receive the fuel bundle therethrough, channel locators carried by the first guide member for engaging the channel about the channel opening to locate the first guide member opening in registration with the channel opening, the second guide member having an opening therethrough larger than the opening through the first guide member for receiving the fuel bundle, structural members maintaining the first and second guide members spaced from one another with the openings therethrough in spaced registration with one another and guide elements carried by the second guide member and spaced thereabout for engaging and guiding the fuel bundle through the registering openings of the first and second guide members and the channel.
In a further preferred embodiment according to the present invention, there is provided a method of inserting a nuclear fuel bundle having a plurality of fuel rods, a water rod and a plurality of spacers into a fuel bundle channel, comprising the steps of (a) providing a guide assembly at an open upper end of the channel with guide elements carried thereby spaced above the open upper end of the channel and (b) lowering the fuel bundle through the guide assembly including engaging the fuel bundle along the guide elements to guide the lower end of the fuel bundle through the channel opening into the channel.
REFERENCES:
patent: 2994657 (1961-08-01), Petrick
patent: 3389056 (1968-06-01), Frisch
patent: 3968008 (1976-07-01), Piepers et al.
patent: 4119489 (1978-10-01), Itoh et al.
patent: 4489037 (1984-12-01), Go
patent: 4676945 (1987-06-01), Barkhurst
patent: 4714583 (1987-12-01), Wachter
Apple, Jr. Edward G.
Peters William C.
Smith David G.
Behrend Harvey E.
General Electric Company
Nixon & Vanderhye
LandOfFree
Methods for guiding a fuel bundle into a channel does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods for guiding a fuel bundle into a channel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for guiding a fuel bundle into a channel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584905