Gaines Blackwell, et al:

In 1995 it was announced that about 100 German WWII U-boats would be salvaged off the Scottish Coast. These subs were scuttled after the end of the war during
"Operation Deadlight, the disposal of the captured U-boat fleet. Because they were scuttled, there is no issue of them being war graves, as vessels sunk in combat would be. The reasons behind the salvage have been questioned, as raising a batch of U-boats doesn't seem to be a particularly economical way of getting scrap metal. In reality, the ships are not being cut up and melted down as ordinary scrap. These U-boats represent one of the last readily available sources of non-radioactive steel and are being salvaged for that "clean Steel."

All steel made since the detonation of the first atom bomb in 1945 has contained tiny amounts of radioactivity. This because the atmosphere now contains trace amounts of radioactivity. The steel-making process involves the use of large amounts of air, which transfers the radioactivity to the steel. Instruments and equipment used for measuring radioactivity must be free from extra background
radiation, so post-1945 "new" steel cannot be used for these purposes. Instead,
pre-1945 "clean" steel is used. The steel i obtained from the scrapping of pre-
1945 ships, and a considerable amount has been obtained from the German ships
scuttled in Scapa Flow at the end of WWI. Obviously. steel obtained from these
relatively limited sources is much more valuable than normal steel. The existing
sources for "clean" have mostly dried up, so the salvage of U-boats is economically justifiable now. The subs will not be melted down after salvage,
rather, plates cut from the hulls will used in their current form. However, since the announcement of the salvage rights in 1995, everything has grown quiet,
and there may be no actual salvage activity, now or in the future.

Hope this helps,

ROBERT M.