> Low-background steel, also known as pre-war steel and pre-atomic steel, is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s.
https://en.wikipedia.org/wiki/Low-background_steel
> Low-background steel, also known as pre-war steel and pre-atomic steel, is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s.
https://en.wikipedia.org/wiki/Low-background_steel