Nuclear reactors having liquid metal alloy fuels and/or moderators
Nuclear reactor systems and associated devices and methods are described herein. A representative nuclear reactor system includes a reactor vessel having a barrier separating a core region from a shield region. A plurality of fuel rods containing a liquid nuclear fuel are positioned in the core region. A liquid moderator material is also positioned in the core region at least partially around the fuel rods. A plurality of heat exchangers can be positioned in the shield region, and a plurality of heat pipes can extend through the barrier. The moderator material is positioned to transfer heat received from the liquid nuclear fuel to the heat pipes, and the heat pipes are positioned to transfer heat received from the moderator material to the heat exchangers. The heat exchangers can transport the heat out of the system for use in one or more processes, such as generating electricity.
1 . A fuel rod for a nuclear reactor, comprising:
a first wall portion defining an active region of a chamber configured to contain a first portion of liquid nuclear fuel in a critical state;
a second wall portion defining an inactive region of the chamber configured to contain a second portion of liquid nuclear fuel, wherein the second wall portion includes an amount of a neutron-absorbing material integrated therein configured to keep the second portion of the liquid nuclear fuel inside the inactive region in a subcritical state, wherein the amount of the neutron-absorbing material is in contact with, and encloses, the second portion of liquid nuclear fuel, and wherein the second wall portion is positioned above the first wall portion, wherein the liquid nuclear fuel is configured to circulate within the chamber between the inactive region and the active region such that the liquid nuclear fuel is burned generally uniformly; and
a filter fluidly positioned above the inactive region and coupled to the chamber for receiving gaseous products generated by the liquid nuclear fuel.
2 . The fuel rod of claim 1 , wherein the filter is integrally formed with the second wall portion.
3 . The fuel rod of claim 1 , wherein the gaseous products comprise xenon and/or krypton.
4 . The fuel rod of claim 1 , wherein the filter defines a serpentine flow path from the chamber to a port.
5 . The fuel rod of claim 1 , wherein the liquid nuclear fuel is a uranium-iron liquid metal (UI-LM) alloy.
6 . The fuel rod of claim 5 , wherein the UI-LM alloy is enriched to 19.5 weight percentage or less uranium-235 (U-235).
7 . A fuel rod for a nuclear reactor, the fuel rod comprising:
a first wall portion defining an active region of a chamber configured to contain a first portion of liquid nuclear fuel, the first portion of liquid nuclear fuel being configured to undergo a fission reaction within the active region that generates heat and one or more fission products;
a second wall portion defining an inactive region of the chamber configured to contain a second portion of the liquid nuclear fuel, wherein the second wall portion includes an amount of a neutron-absorbing material integrated therein configured to keep the second portion of the liquid nuclear fuel inside the inactive region in a subcritical state, wherein the amount of the neutron-absorbing material is in contact with the second portion of liquid nuclear fuel, and wherein the second wall portion is positioned above the first wall portion, wherein the liquid nuclear fuel is configured to circulate within the chamber between the inactive region and the active region; and
a filter fluidly coupled to the chamber for receiving the fission products released from the liquid nuclear fuel.
8 . The fuel rod of claim 7 , wherein the fission products comprise noble gases.
9 . The fuel rod of claim 7 , wherein the filter comprises a first filter member configured to physically capture a first fission product of the fission products and a second filter member configured to chemically bind a second fission product of the fission products.
10 . The fuel rod of claim 7 , wherein the filter defines a serpentine flow path.
11 . The fuel rod of claim 1 , wherein the first portion of the liquid nuclear fuel in the critical state comprises a minimum volume of the liquid nuclear fuel required to maintain criticality in a reactor core that contains the fuel rod.
12 . The fuel rod of claim 1 , wherein the second wall portion includes a greater amount of a neutron-absorbing material than the first wall portion.
13 . The fuel rod of claim 1 , wherein the filter defines a flow path from the chamber through a first filter member and a second filter member to a port, the port being positioned to vent one or more of the gaseous products from the chamber.
14 . The fuel rod of claim 1 , wherein the second wall portion functions as a neutron reflector or a neutron shield.
15 . The fuel rod of claim 1 , wherein the liquid nuclear fuel is configured to circulate between the inactive region and the active region and wherein the liquid nuclear fuel reacts only in the active region such that the liquid nuclear fuel is burned generally uniformly.