Part length fuel rod extension

In a fuel bundle for a boiling water nuclear reactor comprising a plurality of fuel rods secured within an array and extending between upper and lower tie plates, and including at least one additional fuel rod extending from said lower tie plate but terminating short of said upper tie plate, the improvement comprising an extension rod secured to said at least one additional fuel rod and extending substantially to said upper tie plate, said extension rod comprising a hollow tube having a plurality of openings therein including diametrically opposed helical windows, and a flow path structure within said hollow tube radially adjacent said diametrically opposed helical windows and extending over an axial portion of the hollow tube, the flow path configured to cause liquid coolant in the hollow tube to flow outwardly through said openings and be deposited on adjacent fuel rods, wherein said helical windows are each formed by a plurality of tabs partially cut from said tube and bent inwardly toward a longitudinal axis of said tube, said tabs forming said flow path structure.

In a fuel bundle for a boiling water nuclear reactor comprising a plurality of fuel rods secured within an array and extending between upper and lower tie plates, and including at least one additional fuel rod extending from said lower tie plate but terminating short of said upper tie plate, the improvement comprising an extension rod secured to said at least one additional fuel rod and extending substantially to said upper tie plate, said extension rod comprising a hollow tube having a plurality of openings therein and a flow path structure within said hollow tube radially adjacent said plurality of openings and extending over an axial portion of the hollow tube, the flow path configured to cause liquid coolant in the hollow tube to flow outwardly through said openings and be deposited on adjacent fuel rods, wherein said plurality of openings also include at least one pair of adjacent, axially extending slits at a location corresponding to a fuel bundle spacer.

A partial length fuel rod extender adapted to be attached to an upper end of a partial length fuel rod of a nuclear reactor fuel bundle comprising a hollow tube having a plurality of openings therein and a flow path structure within said hollow tube radially adjacent said plurality of openings and extending over an axial portion of the hollow tube, said flow path structure shaped to cause two phase water/steam coolant in said hollow tube to separate such that water flows through said plurality of openings and onto adjacent fuel rods.