Radiation is well-known for destroying both materials and living species. Surprisingly, MIT engineers have found that radiation may help some alloys to self-heal, extending their lifetime. This discovery could help guide future power plant designs.
Radiation accelerates the corrosion of most materials in nuclear reactors, which leads to failure and disastrous consequences. The MIT team and Lawrence Berkeley National Laboratory conducted a study, published in Nature Communications, that set out to evaluate how bad that corrosion would be under different levels of radiation. While inspecting particular alloys of chromium and nickel, the team was astounded to find that radiation caused the material to be more corrosion resistant.
The study was based on a particular type of nuclear reactor that uses molten salts of sodium, potassium, and lithium as a coolant. The combination of salt and heat corroded the metal over time. However, the team found that when this alloy was exposed to radiation from a proton accelerator, it took twice as long to form the corrosion.
Michael Short, the study’s lead researcher, said:
We repeated it dozens of times, with different conditions, and every time we got the same results.
Using transmission electron microscopy, the team examined the alloy surfaces after they’d been exposed to radiation while in contact with salt at 1,202°F (650°C). They found that radiation makes tiny defects in the metal, which allows its atoms to move freely and to fill in the holes made by the corrosive salt quickly.
In addition to helping enlighten future designs for nuclear reactors, the discovery will also enable more accurate estimates of the lifespan of materials in existing facilities around the world.
