ZrSiO­4 and nuclear waste

Scientists don’t find an adequate material to store nuclear waste in. A traditional candidate for the job was zircon (ZrSiO­4), a ceramic mineral that is known to survive geologic processes like erosion, transport and even high-grade metamorphism.

A team in Cambridge published an model that happens to challenge the hopes of zircon as the container to store nuclear waste for an estimated period of 250,000 years. The conclusions of the research it that zircon would lose its ordered structure in a far shorter time, from what can be read at a couple of articles at the Royal Society of Chemistry and Nature.

The researchers estimated the structural damage created by the displacement of zirconium, silicon and oxygen atoms in crystalline zircon following the recoil of the nucleus that emit alpha particle.

Zircon would reach the percolation point when damaged regions within a crystal will start to join up across the crystal and then the material will start to swell and potentially crack, after 210 years. After just 1,400 years the whole crystal structure would be destroyed so the material would be amorphous.

© Kostya Trachenko, Martin Dove & Ekhard Salje.
Structural damage created by displacement of zirconium, silicon and oxygen atoms in crystalline zircon following recoil of a heavy nucleus on emitting an alpha particle.

A loss of ordered chemical structure doesn’t always mean that a material can’t contain nuclear waste, but it looks like we are still far from a solution to nuclear waste.