Hot metal, cool science: Testing alloys in molten lead for future reactors

As the U.S. reimagines its nuclear future, researchers at Oak Ridge National Laboratory are experimenting with molten lead and next-generation materials to reinvent a classic reactor design for a new era of innovation.

Lead-cooled fast reactors use hot, liquid lead to cool the reactor while maintaining the speed of neutrons, a technique that promises gains in fuel efficiency over traditional water-cooled reactors. Alumina-forming austenitic (AFA) stainless steel can withstand the high heat and corrosive environment of a lead-cooled fast reactor, making it an inexpensive candidate for component materials in these advanced reactors.

To evaluate the alloy's performance in these conditions, researchers are testing AFA samples in eight small "rabbit" capsules encased in solid lead in ORNL's High Flux Isotope Reactor, a DOE Office of Science user facility that provides one of the world's highest steady neutron fluxes for materials testing. There, the lead liquefies under intense gamma heating, exposing the alloy to radiation and corrosion damage simultaneously. This synergistic effect provides robust data on how AFA alloys respond to intense conditions.

"The rabbit tests are integral to verifying models and guiding how we engineer materials for lead-cooled fast reactors," said ORNL's Nick Russell. "These insights build confidence and accelerate design decisions for future systems."