Something else that some-one once told me about the few remaining Germanicon vessels at Scapa Flow is that they are a source of pre-nuclear age metals of which small quantities are required. I don't know if there is any truth in this but if I remember correctly I was told that it was used in test equipment for nuclear/radiation testing equipment and it had to be material that hadn't been exposed to the atmosphere since the invention of the atomic bomb. Perhaps some-one with more knowledge than myself could please either confirm or discount this, thanks.