University of Michigan researchers have found a way to create safer and longer lasting nuclear reactors. An important discovery revealed that metal alloys with three or more elements in equal concentrations could be remarkably resistant to radiation damage. Normally, when a metal or an alloy of two metals are exposed to radiation, their surfaces become pocked with tiny cavities.
A recent study has shown that the effectiveness of a metal alloy’s radiation resistance depends on a recipe of at least three ingredients in equal parts.”Based on this study, we now understand how to develop a radiation-tolerant matrix of an alloy,” said Lumin Wang, Professor of Nuclear Engineering and Radioactive Sciences at the University of Michigan.
Radiation Resistance of the Metal Elements
When scientists exposed pure metals and bimetal alloys to radiation, their findings showed their surfaces became damaged.
Like the divot created from scooping ice cream, radiation bombards metallic surfaces and displaces atoms in the surface’s crystalline structure. Next, displaced atoms travel through the rest of the material, and the damaged cavities they leave can pool together to form bigger cavities.
“radiation bombards metallic surfaces and displaces atoms in the surface’s crystalline structure.”
As a result, metal alloys exposed to radiation tend to swell, potentially doubling their initial size. Swelling causes a decline in material density which affects overall material strength. Therefore, controlling cavity formation is the key to controlling swelling, and maintaining material strength.
To solve this, scientists have tried fortifying materials with nanostructures. Yet, the best solution has been inspired by older techniques. Scientists have turned to a method of medieval sword making.
Superior Radiation Resistance Only Costs a Nickel
A collaboration between the Oak Ridge National Laboratory in Tennessee, University of Tennessee, and University of Michigan lead to these discoveries of Nickel’s radiation resistance properties:
- Nickel alone swells when exposed to radiation,
- and Nickel plus one other metal still expands, however less
- and, Nickel plus two other metals swells less still
- while nickel-cobalt-iron-chromium-manganese barely swell at all
- The more elements the alloy contains, the more cumbersome it is on an atomic level.
- As a result, the more uneven the alloy, the slower any displaced particles will travel.
There are many useful applications for effective radiation resistance, but the most immediate might be in Aeronautics. For example, airline crewmembers are technically classified as radiation-exposed workers. Therefore, designing aircraft and spacecraft more resistant to radiation is crucial for crew and passenger safety.
Another added benefit is being able to develop radioactive shielding for aircraft for commercial space flight. As more exploration occurs, the high expense of comprehensive radiation shielding for commercial aircraft will reduce with the steady improvement of aircraft and spacecraft design.