After the detonation of the first nuclear weapons, any newly produced steel has a low dose of nuclear fallout. For applications that need to avoid the backgrou

After the detonation of the first nuclear weapons, any newly produced steel has a low dose of nuclear fallout. For applications that need to avoid the background radiation (like physics research), pre atomic age steel is extracted, like from old shipwrecks. https://en.m.wikipedia.org/wiki/Low-background_steel https://en.m.wikipedia.org/wiki/Low-background_steel