A top end plug design for a nuclear fuel rod or control rod that maximizes the fuel rod length and internal volume for high burn-up, but limits plenum spring melting for eutectic formation margin. The press fit length of the top end plug is increased to increase the distance from the center of heat from the TIG welding process that seals the end plug to the cladding, to the back face of the end plug. A hole in the back of the end plug is enlarged to recover the volume loss from the press fit length increase.

A nuclear reactor fuel rod is a fuel rod for a light-water reactor. The nuclear reactor fuel rod includes a fuel cladding tube and an end plug, both of which are formed of a silicon carbide material. A bonding portion between the fuel cladding tube and the end plug is formed by brazing with a predetermined metal bonding material interposed, and/or by diffusion bonding. The predetermined metal bonding material has a solidus temperature of 1200° C. or higher. An outer surface of the bonding portion, and a portion of an outer surface of the fuel cladding tube and the end plug, which is adjacent to the outer surface of the bonding portion are covered by bonding-portion coating formed of a predetermined coating metal. The predetermined metal bonding material and the predetermined coating metal have an average linear expansion coefficient which is less than 10 ppm/K.

Provided herein is a fuel rod and a fuel assembly for light water reactors in which crack penetration to a fuel cladding tube or an end plug can be prevented even when cracking occurs at the joint between the fuel cladding tube and the end plug for which a ceramic base material is used. A fuel rod 10a for light water reactors includes: a cylindrical cladding tube 11 formed of a ceramic base material; a connection 21 formed of the same or similar material to the cladding tube 11; and an end plug 12a having a concave portion 12f of a continuously curved surface shape adapted to house the connection 21. The end plug 12a is formed of the same or similar material to the cladding tube 11. A slanted surface 11a formed at an end portion of the cladding tube 11, and a slanted surface 12d formed at an end portion of the end plug 12a are joined in contact with each other with a metallic joint material 20. The joint is supported by the connection 21.

Provided herein is a fuel rod and a fuel assembly for light water reactors in which crack penetration to a fuel cladding tube or an end plug can be prevented even when cracking occurs at the joint between the fuel cladding tube and the end plug for which a ceramic base material is used. A fuel rod 10a for light water reactors includes: a cylindrical cladding tube 11 formed of a ceramic base material; a connection 21 formed of the same or similar material to the cladding tube 11; and an end plug 12a having a concave portion 12f of a continuously curved surface shape adapted to house the connection 21. The end plug 12a is formed of the same or similar material to the cladding tube 11. A slanted surface 11a formed at an end portion of the cladding tube 11, and a slanted surface 12d formed at an end portion of the end plug 12a are joined in contact with each other with a metallic joint material 20. The joint is supported by the connection 21.

Systems and methods for providing and using molten salt reactors are described. While the systems can include any suitable component, in some cases, they include a graphite reactor core defining an internal space that houses one or more fuel wedges, where each wedge defines one or more fuel channels that extend from a first end to a second end of the wedge. In some cases, one or more of the fuel wedges comprise multiple wedge sections that are coupled together end to end and/or in any other suitable manner. In some cases, one or more alignment pins also extend between two sections of a fuel wedge to align the sections. In some cases, one or more seals are also disposed between two sections of a fuel wedge. Thus, in some cases, the reactor core can be relatively long (e.g., to be a pipeline reactor). Other implementations are also described.

Packaging structures and systems are used for handling components for use in a nuclear reactor. The packaging protects the component during transport and handling and then dissolves in liquid in the nuclear reactor or fuel pool. The packaging need not be removed and may block flow paths or otherwise interfere with operability were it not for its dissolution. The packaging may include shock absorbers in a fuel assembly or a seal on a water rod in the assembly. Mechanical, frictional, or chemical retaining materials may be used to secure the packaging and may also dissolve in the liquid. For a light water reactor, polymers, protein gels, and plastics can all be used where they will dissolve in the water and are otherwise compatible with reactor chemistry and neutronics. Materials with higher temperatures for solubility may be used because they will dissolve when reactor operations commence.

Packaging structures and systems are used for handling components for use in a nuclear reactor. The packaging protects the component during transport and handling and then dissolves in liquid in the nuclear reactor or fuel pool. The packaging need not be removed and may block flow paths or otherwise interfere with operability were it not for its dissolution. The packaging may include shock absorbers in a fuel assembly or a seal on a water rod in the assembly. Mechanical, frictional, or chemical retaining materials may be used to secure the packaging and may also dissolve in the liquid. For a light water reactor, polymers, protein gels, and plastics can all be used where they will dissolve in the water and are otherwise compatible with reactor chemistry and neutronics. Materials with higher temperatures for solubility may be used because they will dissolve when reactor operations commence.

A method of monitoring in real time pressure resistance welding of a cladding tube and an end plug. The method includes: a first step of detecting welding information including voltage, current, and welding force in a process of pressure resistance welding of a cladding tube and an end plug; a second step of comparing static factors obtained by calculating effective values for the welding information with predetermined reference values, respectively; a third step of calculating dynamic factors for the welding information including the gradient of instantaneous welding force, when the reference values are satisfied in the second step; and a fourth step of determining whether there is defect or not in welding quality by comparing the dynamic factors.

Illustrative embodiments provide a nuclear fission reactor, that includes a reactor vessel, a nuclear fission fuel element capable of generating a gaseous fission product, a valve body defining a plenum for receiving the gaseous fission product, and a valve in operative communication with the plenum for controllably venting the gaseous fission product from the plenum.

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.