This is in response to a reader question, who paid my drinking tab for the day, by clicking. Actually, in the winter, with my depressive cycles, I can barely sniff the stuff, so my tab is low!
Chemical reactions that take place this deep within the earth means that, should all three barriers be breached, the interaction between the iron and groundwater would create large amounts of hydrogen which, under the naturally high pressures 500m below the surface, would prevent the uranium from dissolving.
Good old Sweden! They have chosen to place their nuclear waste, in glaciated, very leaky granite. To do that, they need a story. They have decided to create the world's richest copper mine, by encasing the waste in expensive containers. They can't stop open-channel flow, the copper isn't good enough, so now they pull the old Iron Rabbit, out of the hat.
I don't have a clue how that works. Supposedly, the fizzing iron creates a 'super shield' of hydrogen bubbles which stops the Evil Wizard of Corrosion. Great story!