An annular nuclear fuel pellet in combination with an inserted discrete neutron absorber. The pellet/absorber may be compatible with existing or future nuclear fuel assembly designs. The concept involves the use of nuclear fuel (e.g., uranium dioxide or uranium silicide) formed into annular fuel pellets which can then have a discrete absorber material inserted into the center of the pin. Preferably, the discrete absorber is a non-parasitic absorber. The resulting pellet/absorber can then be stacked into a fuel rod which is arranged in a nuclear fuel assembly. Dimensioning of the annular pellet and absorber and selection of the absorber material and density can allow the concept to be tailored for various nuclear fuel applications.

An annular nuclear fuel pellet in combination with an inserted discrete neutron absorber. The pellet/absorber may be compatible with existing or future nuclear fuel assembly designs. The concept involves the use of nuclear fuel (e.g., uranium dioxide or uranium silicide) formed into annular fuel pellets which can then have a discrete absorber material inserted into the center of the pin. Preferably, the discrete absorber is a non-parasitic absorber. The resulting pellet/absorber can then be stacked into a fuel rod which is arranged in a nuclear fuel assembly. Dimensioning of the annular pellet and absorber and selection of the absorber material and density can allow the concept to be tailored for various nuclear fuel applications.

A thermal-neutron reactor core includes: a solid moderator expanding to a lengthwise direction; a fuel in the moderator, parallel to the lengthwise direction of the moderator, the fuel containing a fissile material; a cooling tube parallel to the lengthwise direction of the moderator; and a plurality of kinds of burnable poison included in the fuel. The may contain a metal hydride. Furthermore, the plurality of kinds of burnable poison may include one burnable poison containing a concentration of one particular isotope of that one burnable poison.

A thermal-neutron reactor core includes: a solid moderator expanding to a lengthwise direction; a fuel in the moderator, parallel to the lengthwise direction of the moderator, the fuel containing a fissile material; a cooling tube parallel to the lengthwise direction of the moderator; and a plurality of kinds of burnable poison included in the fuel. The may contain a metal hydride. Furthermore, the plurality of kinds of burnable poison may include one burnable poison containing a concentration of one particular isotope of that one burnable poison.

An apparatus for removing irradiated capsules containing produced Co-60 from a plurality of burnable absorber rodlets. The apparatus comprises a solenoid that induces an electromagnetic flux into a Co-60 capsule and magnetically locks the Co-60 capsule in parallel with the apparatus. The apparatus is slideable along a longitudinal axis of the burnable absorber rodlet and causes the Co-60 capsule to overcome holding forces exerted on it.

An apparatus for removing irradiated capsules containing produced Co-60 from a plurality of burnable absorber rodlets. The apparatus comprises a solenoid that induces an electromagnetic flux into a Co-60 capsule and magnetically locks the Co-60 capsule in parallel with the apparatus. The apparatus is slideable along a longitudinal axis of the burnable absorber rodlet and causes the Co-60 capsule to overcome holding forces exerted on it.

Passive reactivity control technologies that enable reactivity control of a nuclear thermal propulsion (NTP) system with little to no active mechanical movement of circumferential control drums. By minimizing or eliminating the need for mechanical movement of the circumferential control drums during an NTP burn, the reactivity control technologies simplify controlling an NTP reactor and increase the overall performance of the NTP system. The reactivity control technologies mitigate and counteract the effects of xenon, the dominant fission product contributing to reactivity transients. Examples of reactivity control technologies include, employing burnable neutron poisons, tuning hydrogen pressure, adjusting wait time between burn cycles or merging burn cycles, and enhancement of temperature feedback mechanisms. The reactivity control technologies are applicable to low-enriched uranium NTP systems, including graphite composite fueled and tungsten ceramic and metal matrix (CERMET), or any moderated NTP system, such as highly-enriched uranium graphite composite NTP systems.

A modular and transportable nuclear reactor system comprising a transportation module including a housing. A cask and a radiation shielding section are located in the housing with the shielding surrounding the cask. A high temperature sodium cooled reactor is located in the cask and the reactor is cooled by the natural circulation of in-vessel sodium. The reactor powers at least one thermal-to-electric conversion unit.

Disclosed is a nuclear fuel rod including at least one or more fuel pellets, a cladding tube surrounding the fuel pellets, and burnable absorber inside the cladding tube. The burnable absorber comprises a burnable absorber material and a cladding material surrounding the burnable absorber material. The burnable absorber has a disk shape, and the cladding material is an alloy comprising zirconium.

Disclosed is a nuclear fuel rod including at least one or more fuel pellets, a cladding tube surrounding the fuel pellets, and burnable absorber inside the cladding tube. The burnable absorber comprises a burnable absorber material and a cladding material surrounding the burnable absorber material. The burnable absorber has a disk shape, and the cladding material is an alloy comprising zirconium.