An apparatus and method for pressurizing SiC clad rods of a nuclear core component. A lower end of the rod is sealed with a lower end plug and an upper end of the rod is sealed between the cladding and an external piece of an upper end plug that has a through opening through which a separate internal piece of the upper end plug extends. The internal piece of the upper end plug is initially moveable within the through opening between an upper position that forms a gas tight seal and a lower position that forms a gaseous path through the through opening. The rod is placed in a pressure chamber pressurized to a desired pressure. When the pressure is reduced within the pressure chamber the internal pressure in the rod biases the internal piece of the upper end plug in the upper sealed position.

Fuel rod designs and techniques are provided to encapsulate nuclear fuel pellets in nuclear fuel rods. The tubular cladding in the disclosed fuel rods includes silicon carbide and a metal filler structure formed of a metal that becomes molten during a nuclear reaction of the nuclear fuel pellets and located inside the tubular cladding to include a metal tube that fills in a gap between the nuclear fuel pellets and an interior side wall of the tubular cladding and structured to include a closed metal end cap at one end of the nuclear fuel pellets to leave a space between one end of the interior of the tubular cladding and the closed metal end cap of the metal filler structure as a reservoir.

Fuel rod designs and techniques are provided to encapsulate nuclear fuel pellets in nuclear fuel rods. The tubular cladding in the disclosed fuel rods includes silicon carbide and a metal filler structure formed of a metal that becomes molten during a nuclear reaction of the nuclear fuel pellets and located inside the tubular cladding to include a metal tube that fills in a gap between the nuclear fuel pellets and an interior side wall of the tubular cladding and structured to include a closed metal end cap at one end of the nuclear fuel pellets to leave a space between one end of the interior of the tubular cladding and the closed metal end cap of the metal filler structure as a reservoir.

A nuclear reactor is provided that comprises a vessel that houses a core, comprising a bundle of fuel elements, and immersed in a primary cooling fluid of the core; the fuel elements extend along respective longitudinal and parallel axes and are mechanically supported by respective heads joined to each other and joined to an anchoring structure by support devices acting between adjacent fuel elements, or acting between fuel elements situated on the periphery of the core and the anchoring structure, and which constitute an integral part of the heads of the fuel elements.

A nuclear reactor is provided that comprises a vessel that houses a core, comprising a bundle of fuel elements, and immersed in a primary cooling fluid of the core; the fuel elements extend along respective longitudinal and parallel axes and are mechanically supported by respective heads joined to each other and joined to an anchoring structure by support devices acting between adjacent fuel elements, or acting between fuel elements situated on the periphery of the core and the anchoring structure, and which constitute an integral part of the heads of the fuel elements.

The invention relates to SiC ceramic matrix composite (CMC) claddings with metallic, ceramic and/or multilayer coatings applied on the outer surface for improved corrosion resistance and hermeticity protection. The coating includes one or more materials selected from FeCrAl, Y, Zr and Al—Cr alloys, Cr.sub.2O.sub.3, ZrO.sub.2 and other oxides, chromium carbides, CrN, Zr- and Y-silicates and silicides. The coatings are applied employing a variety of known surface treatment technologies including cold spray, thermal spray process, physical vapor deposition process (PVD), and slurry coating.

The invention relates to SiC ceramic matrix composite (CMC) claddings with metallic, ceramic and/or multilayer coatings applied on the outer surface for improved corrosion resistance and hermeticity protection. The coating includes one or more materials selected from FeCrAl, Y, Zr and Al—Cr alloys, Cr.sub.2O.sub.3, ZrO.sub.2 and other oxides, chromium carbides, CrN, Zr- and Y-silicates and silicides. The coatings are applied employing a variety of known surface treatment technologies including cold spray, thermal spray process, physical vapor deposition process (PVD), and slurry coating.

A fuel assembly according to the present invention includes an end plug disposed on both upper and lower end portions of a fuel rod, and a tie plate that supports at least an upper portion of the end plug. The end plug includes a plurality of support protrusions on a surface of the end plug, and a closed-loop spring having a portion that is inserted through an opening portion formed in the end plug and is stored in a single space formed in the end plug, and a remaining portion protruding to the outside of the end plug. The end plug is supported by the plurality of support protrusions and the closed-loop spring in a state in which the plurality of support protrusions and the closed-loop spring are in contact with an inner wall of an insertion hole formed in the tie plate.

A fuel assembly according to the present invention includes an end plug disposed on both upper and lower end portions of a fuel rod, and a tie plate that supports at least an upper portion of the end plug. The end plug includes a plurality of support protrusions on a surface of the end plug, and a closed-loop spring having a portion that is inserted through an opening portion formed in the end plug and is stored in a single space formed in the end plug, and a remaining portion protruding to the outside of the end plug. The end plug is supported by the plurality of support protrusions and the closed-loop spring in a state in which the plurality of support protrusions and the closed-loop spring are in contact with an inner wall of an insertion hole formed in the tie plate.

A nuclear fuel rod comprises nuclear fuel contained in a cladding, the cladding comprising a tube and two plugs, the tube extending along a central axis and having two ends, each plug being attached to a corresponding end of the tube by sealing the end of the tube. The tube is covered by a tube coating extending over the entire length of the tube from one end of the tube to the other.