Abstract
According to a current concept, copper canisters
of thickness 0.05 m will be safe for nuclear waste containment
for 100,000 years. We show that more than 1 m copper
thickness might be required for 100,000 years durability
based on water exposures of copper for 20 h, 7 weeks,
15 years, and 333 years. An observed evolution of hydrogen
which involves heterogeneous catalysis of molecular
hydrogen, first principles simulations, thermodynamic considerations
and corrosion product characterization provide
further evidence that water corrodes copper resulting in the
formation of a copper hydroxide. These findings cast additional
doubt on copper for nuclear waste containment and
other important applications.

http://www.sr.se/Diverse/AppData/Isidor/files/3345/7050.pdf

Still, one might add that this, even if true, is a storm in a water glass from a safety point of view, as the waste actually doesn't need to be kept contained for 100.000 years (that number was taken completely out of a hat, as they felt it would be impossible to have a debate on different risks over differens time spans with the public), when it reaches the radioactivity of natural uranium. After a few hundred years it's not dangerous to be close to, and it would only kill you if managed to ingest it into your body. Which, all things considered, is just as unlikely now as ever.

Even so, it's still bad PR, and nuclear power is very much about PR.

Peak oil is not an energy crisis. It is a liquid fuel crisis.