• Number 310  |
• April 26, 2010

Safer nuclear reactors could result from Los Alamos research

Self-repairing materials within nuclear reactors may one day become a reality as a result of research by Los Alamos National Laboratory scientists.

In a paper appearing in the journal Science, Los Alamos researchers report a surprising mechanism that allows nanocrystalline materials to heal themselves after suffering radiation-induced damage. Nanocrystalline materials are those created from nanosized particles, in this case copper particles. A single nanosized particle-called a grain-is the size of a virus or even smaller. Nanocrystalline materials consist of a mixture of grains and the interface between those grains, called grain boundaries.

When designing nuclear reactors or the materials that go into them, one of the key challenges is finding materials that can withstand an outrageously extreme environment. In addition to constant bombardment by radiation, reactor materials may be subjected to extremes in temperature, physical stress, and corrosive conditions. Exposure to high radiation alone produces significant damage at the nanoscale.

Designing materials that can withstand radiation-induced damage is very important for improving the reliability, safety and lifespan of nuclear energy systems. Because nanocrystalline materials contain a large fraction of grain boundaries-which are thought to act as sinks that absorb and remove defects-scientists have expected that these materials should be more radiation tolerant than their larger-grain counterparts. Nevertheless, the ability to predict the performance of nanocrystalline materials in extreme environments has been severely lacking because specific details of what occurs within solids are very complex and difficult to visualize.

Recent computer simulations by the Los Alamos researchers help explain some of those details.

In the Science paper, the researchers describe the never-before-observed phenomenon of a "loading-unloading" effect at grain boundaries in nanocrystalline materials. This loading-unloading effect allows for effective self-healing of radiation-induced defects.

http://www.lanl.gov/news/releases/safer_nuclear_reactors_could_result_from_los_alamos_research.html

[James Rickman, 505.665.9203,
elvis@lanl.gov]