Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: In a fuel bundle for a boiling water nuclear reactor comprising a plurality of fuel rods (20) secured within an array and extending between upper and lower tie plates (24, 22), and including at least one additional partial length fuel rod (20') extending from said lower tie plate (22) but terminating short of said upper tie plate (24), an improvement in the form of a removable extension rod (32) secured to said at least one additional fuel rod (20') and extending substantially to said upper tie plate (24). The removable extension rod (32) also permits variance in the reactivity of the partial length fuel rod (20') particularly in the two phase region of the bundle (10).

Abstract: An improved stainless steel composition and an improved stainless Ni-based alloy are disclosed for use in nuclear reactor environments. The improved stainless alloys include a stainless steel and a stainless nickel based alloy that are particularly well adapted for use in reactor components that are positioned adjacent to components formed from a zirconium based metal. The improved stainless steel is an austenitic stainless steel material that include less than approximately 0.2 percent manganese by weight, but does include sufficient austenitic stabilizer to prevent a martensitic transformation during fabrication or use in a reactor environment. In one preferred embodiment, the stainless alloy is formed without any significant amount of manganese.

Abstract: The lower tie plate grid includes cylindrical bosses and webs interconnecting the bosses for supporting nuclear fuel rods and defining flow openings through the grid. Coolant flows through the flow openings for flow upwardly about the fuel rods. The grid includes upper and lower portions and a screen is disposed between the upper and lower grid portions upon assembly with the bosses and webs of the respective upper and lower grid portions in registry with one another. The grid portions are welded to one another whereby the apertured screen serves to separate debris from the coolant flowing through the flow openings. The screen has openings in registry with the openings defined by the bosses for receiving the end plugs of the fuel rods.

Abstract: A unitary one-piece lower tie plate grid has a lower portion and an upper portion for supporting the fuel rods. The lower tie plate grid includes cylindrical boss portions extending upwardly from the lower grid portion and arranged in square matrices for receiving the lower end plugs of the fuel rods. Web portions extending upwardly from the lower tie plate portion interconnect the boss portions along the sides of the matrices. The lower grid portion includes a plurality of openings which open into the flow spaces defined by the convex portions of the bosses and the webs within each square matrix of the upper portion of the tie plate. Coolant flows through the openings into the flow spaces for further flow upwardly about the fuel rods. The openings are radiussed adjacent their lower ends and have divergent side walls downstream of a throat area to define a flow venturi.

Abstract: The disclosed invention consists of a ceramic form of fuel for a nuclear reactor comprising an oxide of a fissionable element and containing therein a consumable neutron absorbing agent. The ceramic fissionable fuel product provides longer fuel performance in nuclear reactor service.

Abstract: Zirconium-base alloy channels and fuel cladding tubes having unique resistance to accelerated pustular corrosion in the boiling water reactor environment are produced by a heat treatment causing segregation of intermetallic particulate precipitate phase in two dimensional arrays preferably located along grain boundaries and subgrain boundaries throughout the alloy body.