The present disclosure is generally related to methods, systems and devices for forming a randomized grain structure coating on a substrate of a component for use in a nuclear reactor to provide protection against corrosion and, more particularly, is directed to improved methods, systems and devices for forming a randomized grain structure coating on a zirconium alloy nuclear fuel cladding tube using a cathodic arc (CA) physical vapor deposition (PVD) process to provide protection against corrosion in both normal operation and in transient and accidents of the nuclear reactor.

The present disclosure is generally related to methods, systems and devices for forming a randomized grain structure coating on a substrate of a component for use in a nuclear reactor to provide protection against corrosion and, more particularly, is directed to improved methods, systems and devices for forming a randomized grain structure coating on a zirconium alloy nuclear fuel cladding tube using a cathodic arc (CA) physical vapor deposition (PVD) process to provide protection against corrosion in both normal operation and in transient and accidents of the nuclear reactor.

An assembly configured to seal an end plug on a plugged end of a fuel tube is disclosed. The assembly includes a seal weld chamber assembly and a helium flow stop assembly (HFSA) removably coupled to the seal weld chamber assembly. The seal weld chamber assembly includes a welding chamber and a plunger fluidically coupled to the welding chamber. A helium source is configured to supply helium to the welding chamber. The end plug of the fuel tube is positionable within the welding chamber via the plunger. The HFSA is configured to prevent helium from escaping the welding chamber through the plunger.

An assembly configured to seal an end plug on a plugged end of a fuel tube is disclosed. The assembly includes a seal weld chamber assembly and a helium flow stop assembly (HFSA) removably coupled to the seal weld chamber assembly. The seal weld chamber assembly includes a welding chamber and a plunger fluidically coupled to the welding chamber. A helium source is configured to supply helium to the welding chamber. The end plug of the fuel tube is positionable within the welding chamber via the plunger. The HFSA is configured to prevent helium from escaping the welding chamber through the plunger.

Composite structures are provided whose composite matrix is a fully-dense (greater than 95%) magnesium oxide-containing phase and whose entrained phase, by virtue of its' decomposition temperature or chemical reactivity, would otherwise not be fabricable. Notably, a methodology is provided whereby a range of composite structures are formed by applying an advanced manufacturing technique and a blend of ceramic powder whose sintering is enhanced by small amounts of a metal halide sintering aid. This methodology and process significantly lowers the processing temperature of refractory ceramics such as magnesium oxide allowing formation of ceramic bodies incorporating phases such as metal hydrides, fragile ceramic phases, and highly reactive species such as beryllides. In all cases, the final product is substantially-free, or even devoid, of the metal halide sintering aid, resulting in a phase-pure ceramic matrix composed of the host phase and the entrained phase.

Composite structures are provided whose composite matrix is a fully-dense (greater than 95%) magnesium oxide-containing phase and whose entrained phase, by virtue of its' decomposition temperature or chemical reactivity, would otherwise not be fabricable. Notably, a methodology is provided whereby a range of composite structures are formed by applying an advanced manufacturing technique and a blend of ceramic powder whose sintering is enhanced by small amounts of a metal halide sintering aid. This methodology and process significantly lowers the processing temperature of refractory ceramics such as magnesium oxide allowing formation of ceramic bodies incorporating phases such as metal hydrides, fragile ceramic phases, and highly reactive species such as beryllides. In all cases, the final product is substantially-free, or even devoid, of the metal halide sintering aid, resulting in a phase-pure ceramic matrix composed of the host phase and the entrained phase.

A nuclear fuel element includes a core comprising a fissile element and an additional element. A protective structure surrounds the core and comprises at least a first material surrounding the nuclear fuel. The first material comprises the fissile element and the additional element and comprises a greater than stoichiometric amount of the additional element. An outer portion of the nuclear fuel element comprises a metal. Related nuclear fuel elements, and related methods are also disclosed.

A nuclear fuel element includes a core comprising a fissile element and an additional element. A protective structure surrounds the core and comprises at least a first material surrounding the nuclear fuel. The first material comprises the fissile element and the additional element and comprises a greater than stoichiometric amount of the additional element. An outer portion of the nuclear fuel element comprises a metal. Related nuclear fuel elements, and related methods are also disclosed.

Disclosed are a nuclear fuel pellet having enhanced thermal conductivity and a method of manufacturing the same, the method including (a) a step of manufacturing a mixture including a nuclear fuel oxide powder and a thermally conductive plate-shaped metal powder; and (b) a step of molding and then heat-treating the thermally conductive plate-shaped metal powder to have an orientation in a horizontal direction in the mixture, thereby forming a pellet.

The method includes forming an inner monolithic layer from crystals of beta phase stoichiometric silicon carbide on a carbon substrate in the form of a rod by chemical methylsilane vapor deposition in a sealed tubular hot-wall CVD reactor. The method further includes forming a central composite layer over the inner monolithic layer by twisting continuous beta phase stoichiometric silicon carbide fibers into tows, transporting the tows to a braiding machine, and forming a reinforcing thread framework. A pyrocarbon interface coating is built up by chemical methane vapor deposition in a sealed tubular hot-wall CVD reactor. Then, a matrix is formed by chemical methylsilane vapor deposition in the reactor. A protective outer monolithic layer is formed from crystals of beta phase stoichiometric silicon carbide over the central composite layer by chemical methylsilane vapor deposition in a CVD reactor. And then the carbon substrate is removed from the fabricated semi-finished product.