A composite nuclear reactor component comprises a support and a protective layer (2). The support contains a substrate (1) based on a metal. The substrate is coated with an interposed layer (3) positioned between the substrate (1) and the protective layer (2). The protective layer (2) is composed of a material which comprises amorphous chromium carbide. The nuclear reactor component provides for improved resistance to oxidation, hydriding, and/or migration of undesired material.

A composite nuclear reactor component comprises a support and a protective layer (2). The support contains a substrate (1) based on a metal. The substrate is coated with an interposed layer (3) positioned between the substrate (1) and the protective layer (2). The protective layer (2) is composed of a material which comprises amorphous chromium carbide. The nuclear reactor component provides for improved resistance to oxidation, hydriding, and/or migration of undesired material.

To provide is a fuel assembly capable of easily adjusting average MA enrichment in an inner blanket region. An inner core fuel assembly 7 loaded in an inner core region 2 of a core of a fast reactor includes a plurality of fuel rods 10 and a plurality of fuel rods 19. Each of the fuel rods 10 includes a lower core fuel region 12, an inner blanket region 11, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13, and a U—Zr metal fuel is disposed in the inner blanket region 11. Each of the fuel rods 19 includes a lower core fuel region 12, an inner blanket region 20, and an upper core fuel region 13. A U—Pu—Zr metal fuel is disposed in the lower core fuel region 12 and the upper core fuel region 13 of the fuel rod 19, and a MA-Zr metal fuel is disposed in the inner blanket region 20. By adjusting the number of the fuel rods 10 and the number of the fuel rods 19, MA enrichment in the inner blanket region 9 of the fuel assembly 7 can be easily adjusted.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.

A method of loading fuel in multiple reactor cores associated with a plurality of fuel cycles. The method includes, in a first fuel cycle, loading a first reactor core with a first fuel assembly selected from a first batch of fuel, loading the first reactor core with a first partially spent fuel assembly from a second batch of fuel, loading a second reactor core with a second fuel assembly from the first batch of fuel, and loading the second reactor core with a second partially spent fuel assembly from the second batch of fuel. In a second fuel cycle, which is performed after a completion of the first fuel cycle, the method includes loading the second reactor core with a fresh fuel assembly, and loading the second reactor core with the first fuel assembly from the first batch of fuel.

The fuel element of the present invention includes a cladding tube and a metal fuel contained in the cladding tube, in which a gas plenum region is formed above the metal fuel and inside the cladding tube and has a small-diameter portion in the gas plenum region. Further, the fuel assembly of the present invention includes the fuel element of the present invention and a wrapper tube surrounding the fuel element, in which a coolant material passage is formed between the fuel element and the fuel element. Further, the core of the present invention includes an inner core fuel region loaded with the fuel assembly according to the present invention, and an outer core fuel region loaded with the fuel assembly of the present invention.

A molten salt nuclear reactor a neutron moderator core that has an inner region that defines channels of a first diameter separated by a first pitch and, an outer region that defines channels of a second diameter separated by a second pitch. The first diameter is larger than the second diameter and the first pitch is larger than the second pitch. This configuration allows for an increased capture of neutrons by fertile elements in the outer region. That is, less neutrons are lost to the outside of the core. The configuration is such that the neutron multiplication factor is larger than one in the inner portion and lower than one in the outer portion.

A molten salt nuclear reactor a neutron moderator core that has an inner region that defines channels of a first diameter separated by a first pitch and, an outer region that defines channels of a second diameter separated by a second pitch. The first diameter is larger than the second diameter and the first pitch is larger than the second pitch. This configuration allows for an increased capture of neutrons by fertile elements in the outer region. That is, less neutrons are lost to the outside of the core. The configuration is such that the neutron multiplication factor is larger than one in the inner portion and lower than one in the outer portion.

A composite moderator medium for nuclear reactor systems and a method of fabricating a composite moderator block formed of the composite moderator medium. The composite moderator medium includes two or more moderators, such as a low moderating material and a high moderating material. The high moderating material has a higher neutron slowing down power compared to the low moderating material. The low moderating material includes a moderating matrix of silicon carbide or magnesium oxide. The high moderating material is dispersed within the moderating matrix and includes beryllium, boron, or a compound thereof. The high moderating material is encapsulated within the low moderating material such that the high moderating material is not exposed outside of the low moderating material. The method can include selecting a sintering aid and a weight percent of the sintering aid in a composite moderator mixture based on the low moderating material and spark plasma sintering.