Following the armistice of 1918, the German Navy was moved to Scapa Flow, and moored there with their German crews while the greedy allies decided who would get what ships.
Ze Germans however, wanted nothing of this, so despite the armistice, scuttled the ships, an act of war in and of its own. Some of the ships were saved and scuttled as target practice in the 1920s, but most went to the bottom. Some were refloated, but again, most are still there. There’s a wikipedia article, but don’t read it right now..
Fast forward to the 1940s. The somewhat unfair settlement against the germans has lead (in part) to another world war, and the americans develop a massive weapon, the likes of which have never been seen before. The war in Europe finishes, and this new weapon brings about the end to the war in Asia. More of these mighty weapons are tested, and from the fallout, the world’s background radiation increases just a bit. So much so that most of the world’s steel refineries produce steel that contains trace levels of radiation (in some cases, not so trace..)
Anyway, this produces a problem. How do you compare radiation levels when everything is now radioactive, to a degree? Well, the easy way is to compare it to something you know is mostly non radioactive. So they grab steel that’s been under water since the 1920s, and thus shielded from most radiation. Remember the Kaiser’s ships? Yup, them.
The circle of life continues.