Nuclear reactors could become safer: report

The study found a previously unknown effect where atoms inside reactor walls became packed together during exposure to radiation, causing damage but then spread out again repairing any defects, reports dailymail.co.uk.

Scientists believe the discovery could lead to the next generation of highly radiation-tolerant materials in new nuclear power stations.

When designing nuclear reactors, one of the key challenges is finding materials that can withstand the extreme environment.

Materials are constantly bombarded with radiation, extremes in temperature, physical stress and corrosive conditions.

Exposure to high radiation alone causes significant damage on a nanoscale level.
It can cause individual atoms or groups of atoms to be shaken out of place - known as interstitial atoms - which therefore cause gaps in a material.

These gaps and interstitial atoms build up over time causing the material to become brittle, swell and harden and can lead to catastrophic failure in the reactor.

Designing the nano-crystalline materials - from tiny copper particles - to withstand radiation-induced damage is therefore very important for improving the reliability, safety and longevity of nuclear power stations.

Computer simulations carried by scientists at Los Alamos National Laboratory, in New Mexico, the US, discovered the 'loading-unloading' effect in the interface between single nano-sized particles - known as grains.

The study, published in the Science journal, looked at the interaction between defects and the interface between grains on time scales ranging from one trillionth of a second to one millionth of a second.

On the shorter timescales, radiation-damaged materials underwent a 'loading' process where the interstitial atoms became trapped.

These atoms later became 'unloaded' into the gaps that had been created and therefore repaired the material.

Although researchers found that some energy was required for the effect to take place, the amount of energy was much lower than that required to operate conventional repair mechanisms.