GA progresses with silicon carbide fuel cladding development

22 July 2024

General Atomics has manufactured the first batch of full-length SiGA silicon carbide composite tubes designed for pressurised water reactors. The company is developing nuclear fuel rods that can withstand higher temperatures than materials currently used.

SiGA woven silicon carbide nuclear fuel cladding (Image: GA)

General Atomics Electromagnetic Systems (GA-EMS) is under contract with the US Department of Energy (DOE) through its Accident Tolerant Fuel Program to advance silicon carbide fuel cladding technology for enhanced efficiency and improved safety of the US nuclear reactor fleet.

SiGA is a silicon carbide composite material which, because of its hardness and ability to withstand extremely high temperatures, has been used for industrial purposes for decades. It now forms the basis for the development of nuclear reactor fuel rods that can survive temperatures far beyond that of current materials, such as zirconium alloy.

GA-EMS has successfully created silicon carbide nuclear fuel cladding tubes. The company's technology incorporates silicon carbide fibre into its cladding. The combination creates an incredibly tough and durable engineered silicon carbide composite material which can withstand temperatures up to 3800°F (2093°C) - about 500 degrees hotter than the melting point of zirconium alloy.

GA-EMS has already created 6-inch (15cm) long SiGA rodlets and 3-foot (91cm) cladding samples that meet stringent nuclear power reactor-grade requirements and will undergo irradiation testing at DOE's Idaho National Laboratory.

Recent work has demonstrated the process is scalable to full-length 12-foot (3.6m) fuel rods.

"This manufacturing demonstration of SiGA cladding at lengths of 12 feet is a notable milestone in our efforts to bring this innovative technology to market," said GA-EMS President Scott Forney. "We have been executing a strategic fabrication and test programme and advancing manufacturing efficiency and scale-up of this enabling product, including demonstration of cladding robustness through collaborative test campaigns with the national labs."

"SiGA cladding is engineered to enhance the safety and affordability of the existing nuclear reactor fleet," added Christina Back, vice president of GA-EMS Nuclear Technologies and Materials. "The material's in-core stability can reduce the frequency for refuelling the core, which will improve nuclear power plant economics, while providing additional fuel protection in the unlikely case of an accident.

"This manufacturing milestone showed excellent property uniformity across the length of the part and throughout the production batch. As we continue to validate our scale-up work, these key performance metrics demonstrated at shorter 6-inch to 3-foot lengths, will continue to be the hallmark of SiGA technology at full length."

In addition to scaling fabrication techniques and process improvements, GA-EMS said it is focused on advanced performance testing, and modelling tool development, for SiGA fuel rods.

GA originally developed its SiGA composite for its Energy Multiplier Module (EM2) small modular reactor design. This is a modified version of its Gas-Turbine Modular Helium Reactor (GT-MHR) design.

In February 2020, Framatome and GA agreed to evaluate the feasibility of using SiGA in fuel channel applications through thermomechanical and corrosion testing. The long-term goal is to demonstrate the irradiation of a full-length fuel channel in support of licensing and commercialisation.

Researched and written by World Nuclear News