A team of US researchers has come up with a novel metal alloy for nuclear fission reactors that can reportedly withstand stresses of up to 600 megapascals (MPa) at room temperature.The experimental alloy, called V555, was developed at the Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL). The scientists went through nearly 1,000 potential metal combinations to identify the most promising formula for the new alloy. To rapidly screen, simulate, as well as optimize the materials, the scientists used a computational approach called robust alloy design (RAD). It can identify materials that could withstand the extreme temperatures, radiation, and mechanical stress found inside nuclear reactors.PNNL said that the alloy has undergone initial room-temperature tests. “The work has developed into a pathway for the nuclear materials community to explore and evaluate a broader range of materials for future nuclear systems,” Osman El Atwani, PhD, a materials scientist and study leader, said. New reactor materialsTraditional cladding materials include steels and zirconium-based alloys, such as Zircaloy. However, as per El Atwani, new alloys from multiple principal elements could have better properties through changes in their metal composition. To select different elements and create entirely new compositions, he and his team created the eight-step RAD process. It evaluates potential materials against several requirements, such as radiation resistance and manufacturability.Pacific Northwest National Laboratory materials scientists Mohan Nartu using an arc melter to make a new alloy sample called V555.Credit: Eddie Pablo / Pacific Northwest National LaboratoryThe group initially identified around 724 alloy compositions with promising traits by relying on the approach. They then turned to the RAD scoring system to narrow the selection. The assessment tool ranks alloys based on their suitability for nuclear reactors. The team eventually selected V555 for initial lab tests to see if the computational approach could work in practice.“The standard practice is swapping this element with that, and that element with this,” Mohan Nartu, PhD, a PNNL materials scientist who worked on the project, revealed. “While that technically gives you a new material, you didn’t change the broth, so the soup is still old. You’re still going to be somewhat limited.”A strong metal alloyAfter selecting V555, the team made samples to test its structure and strength. To their surprise, initial room-temperature tests showed an estimated yield strength, which refers to the amount of stress a material can withstand before it begins to permanently deform, of approximately 500 to 600 MPa.While the early results showed the alloy’s strength, more tests are needed to confirm whether it can be used in nuclear reactors. The team also found that unused V555 material could be recycled to produce additional samples without affecting their quality. This could reduce the material waste during experimental testing.Pacific Northwest National Laboratory materials scientist Osman El Atwani holds a flat sample of a new alloy called V555 (left) that will be cut into a smaller sample (right) for strength testing.Credit: Eddie Pablo / Pacific Northwest National LaboratoryThe researchers will now examine how V555 withstands heat, radiation, and other reactor conditions. They will also test additional compositions identified through the RAD process. The research was backed by the DOE’s Office of Nuclear Energy through its Innovative Nuclear Materials program.“We wanted to show that you can actually choose elements from scratch, if you have the right criteria in mind, and can systematically design a material for nuclear applications,” Nartu concluded in a press release. The study has been published in the journal Materials & Design.