Breakthrough cladding tech promises longer life for US nuclear fuel

A San Diego-based firm has achieved a breakthrough in the development and testing of a new type of nuclear fuel cladding technology.

General Atomics Electromagnetic Systems (GA-EMS) confirmed that it reached another significant milestone in its Silicon Carbide (SiC) nuclear fuel cladding technology.

The company revealed that its recent performance testing on GA-EMS’ patented, localized SiC joining method has shown excellent performance under the corrosive water conditions expected in the current fleet of pressurized water nuclear reactors, marking a significant step in advancing the readiness of SiGA cladding for reactor testing.

SiGA can survive temperatures far beyond that of current materials

SiGA is a silicon carbide (SiC) composite material that forms the basis for the development of nuclear reactor fuel rods that can survive temperatures far beyond that of current materials. The multilayer composite cladding structure offers high temperature performance and other operational benefits for current and future nuclear reactors.

It’s is sealed with a fully-SiC joining process, enabling exceptional stability during operational temperature cycling.

“Our patented local joining process seals the fuel rods without exposing the nuclear fuel pellets to high temperature water. Our SiC cladding and localized joining method form a complete solution to fully and safely contain the solid fuel and enable it to withstand temperatures six times greater than the expected light-water, pressurized water reactor conditions,” said Scott Forney, president of GA-EMS.

“The local SiC joining process is also proving to reduce processing time, supporting the scale-up of efficient domestic manufacturing capability to provide safe accident tolerant fuel cladding for the nuclear fleet.”

Cladding plays key role in protecting fuel

Fuel cladding, which is a barrier between the reactor coolant and nuclear fuel pellets, plays a key role in protecting the fuel while ensuring the safety of a nuclear power plant. 

Fuel is stacked into cladding tubes, and the ends of the tubes are joined to form hermetic seals for the fuel rods. GA-EMS’ SiGA cladding offers superior high temperature and irradiation resistance, which can significantly improve the operating performance, economic efficiency, and safety of light water reactors, according to a press release.

“We’ve successfully verified irradiation resistance of our ceramic joints at the Oak Ridge National Laboratory High Flux Isotope Reactor test reactor. Now, GA-EMS is working to evaluate the quality of the SiGA joints under the high temperature, high pressure, and corrosive water coolant environment expected in pressurized water reactors,” said Dr. Christina Back, vice president of GA-EMS Nuclear Technologies and Materials.

“We achieved a critical milestone this past month, with results confirming that joints fabricated by our local SiC joining process remained gas-tight after 180 days of exposure in Westinghouse’s reactor coolant test facility. It is very exciting to be moving to the ultimate demonstration of joint performance testing in the Advanced Test Reactor at Idaho National Laboratory in the presence of both corrosive water coolant and neutron irradiation.”

SiGA provides greater stability and safety at temperatures up to 3,452° Fahrenheit (1900°C), well beyond that of metal fuel rod claddings. SiGA cladding would also enable higher powers and longer fuel lifetimes, thereby enhancing overall reactor performance and economics. GA-EMS has been under contract with the Department of Energy (DOE) to support the Accident Tolerant Fuel Program and advance GA-EMS’ silicon carbide fuel cladding technology for future deployment in U.S. nuclear reactors.