LOWER END FITTING FOR NUCLEAR FUEL ASSEMBLY MADE FROM INTERSECTING METAL STRIPS
A fuel assembly including a plurality of fuel rods arranged mutually in parallel wherein the fuel rods include a fissile material, a plurality of guide tubes arranged in parallel with and interspersed amongst the fuel rods, an upper end fitting connected with upper ends of the guide tubes, and a lower end fitting connected with lower ends of the guide tubes. At least one of the upper end fitting and the lower end fitting includes a grid formed by interlocking metal strips secured together at intersections between the metal strips.
1 . An apparatus comprising:
a fuel assembly including:
a plurality of fuel rods arranged mutually in parallel wherein the fuel rods include a fissile material,
a plurality of guide tubes arranged in parallel with and interspersed amongst the fuel rods,
an upper end fitting connected with upper ends of the guide tubes, and
a lower end fitting connected with lower ends of the guide tubes,
wherein at least one of the upper end fitting and the lower end fitting includes a grid formed by interlocking metal strips secured together at intersections between the metal strips.
2 . An apparatus as set forth in claim 1 , wherein the intersecting metal strips are welded together at intersections between the metal strips.
3 . An apparatus as set forth in claim 1 , wherein the terminal ends of the interlocking metal strips are bounded by outer strips.
4 . An apparatus as set forth in claim 1 , wherein the grid includes a plurality of openings through which a bolt portion of a guide tube assembly can pass there through.
5 . An apparatus as set forth in claim 1 , wherein the lower end fitting includes said grid formed by interlocking metal strips secured together at intersections between the metal strips
6 . An apparatus as set forth in claim 5 , wherein the lower ends of the guide tubes include guide tube end plugs connected with the lower end fitting.
7 . An apparatus as set forth in claim 6 , wherein the guide tube end plugs include non-circular projections for mating with non-circular grid openings in the lower end fitting.
8 . An apparatus as set forth in claim 1 , wherein the interlocking metal strips include stamped metal strips.
9 . An apparatus as set forth in claim 1 , wherein the interlocking metal strips comprise stainless steel, Inconel, or a zirconium alloy.
10 . An assembly comprising:
a plurality of spacer grids;
a plurality of guide tubes extending through the spacer grids; and
a lower end fitting attached to the lower ends of the guide tubes, the lower end fitting comprising a grid formed by intersecting metal strips secured together at intersections between the metal strips.
11 . An assembly as set forth in claim 10 , wherein the intersecting metal strips are welded together at intersections between the metal strips.
12 . An assembly as set forth in claim 10 , wherein the lower end fitting is not a machined or cast element.
13 . An assembly as set forth in claim 10 , wherein ends of the intersecting metal strips are at least partially bounded by one or more outer strips.
14 . An assembly as set forth in claim 10 , wherein the metal strips do not include nuclear fuel rod retention features.
15 . An assembly as set forth in claim 10 , wherein the metal strips do not include springs or dimples configured to engage nuclear fuel rods.
16 . An assembly as set forth in claim 10 , further comprising:
a bundle of fuel rods comprising fissile material held together by the spacer grids; and
an upper end fitting attached to upper ends of the guide tubes;
wherein the assembly including the spacer grids, guide tubes, lower end fitting, upper end fitting, and bundle of fuel rods defines a nuclear fuel assembly.
17 . A pressurized water reactor (PWR) including:
a nuclear core comprising nuclear fuel assemblies as set forth in claim 16 ,
a cylindrical pressure vessel having a vertically oriented cylinder axis and containing the nuclear core immersed in primary coolant water, and
a hollow cylindrical central riser disposed concentrically with and inside the cylindrical pressure vessel, a downcomer annulus being defined between the hollow cylindrical central riser and the cylindrical pressure vessel.
18 . A method comprising:
arranging a plurality of metal strips in an intersecting arrangement to form a grid;
securing the metal strips together at intersections between the metal strips to form an end fitting; and
attaching ends of guide tubes to the end fitting.
19 . The method of claim 18 , wherein the securing includes welding the metal strips together at intersections between the metal strips.
20 . The method of claim 18 , further comprising:
forming the metal strips by a stamping process.
21 . An apparatus comprising:
an end fitting for a nuclear fuel assembly, the end fitting comprising an assembly of intersecting metal strips secured together at intersections between the strips.
22 . The apparatus of claim 21 wherein the intersecting metal strips are welded together at intersections between the strips.
23 . The apparatus of claim 21 wherein the metal strips do not include retention features for engaging nuclear fuel rods.