Researchers at Massachusetts Institute of Technology (MIT) (Cambridge, Massachusetts, USA) and in California have now found that when certain alloys are exposed to radiation, their resistance improves rather than degrades—an outcome that can potentially double a material’s useful lifetime. This finding has the potential to support cutting-edge reactor designs, including molten-salt-cooled fission reactors, and new fusion reactors such as the SPARC design under development by MIT and Commonwealth Fusion Systems, a new private company also based in Cambridge.
According to Michael Short, MIT professor of nuclear engineering, the researchers initially wanted to determine how much radiation would increase the corrosion rate in certain nickel and chromium alloys. When initial experiments proved difficult to execute, the researchers surrounded the material with a battery of sensors. The tests showed that corrosion was reduced, rather than accelerated, when bathed in radiation.
“We repeated it dozens of times, with different conditions,” says Short, “and every time we got the same results [of delayed corrosion].”
To create the ideal reactor environment for their experiments, the team used molten sodium, lithium, and potassium salt—the latter substance served as a coolant for both the nuclear fuel rods in a fission reactor and the vacuum vessel in a future fission reactor. When hot molten salt comes into contact with metal, corrosion rapidly occurs. However, in the case of nickel-chromium alloys, the researchers discovered that corrosion took twice as long to develop when bathed in radiation from a proton accelerator.
According to Short, the ability to accurately predict the useable lifetime of critical reactor components could reduce the need for replacing parts preemptively. He adds that the discovery could be used for a series of proposed designed for safer, efficient fusion reactors, including ones that provide electricity with no greenhouse gas emissions and greatly reduced radioactive waste. “It’s not particular to any one design,” Short says. “It helps everybody.”
The findings of the MIT team were reported in the journal Nature Communications in a paper authored by Short, graduate student Weiyue Zhou, and five others at MIT and at the Lawrence Berkeley National Library, a Department of Energy Office of Science lab managed by the University of California, Berkeley.
Source: MIT News, www.news.mit.edu.