Low-background steel is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s . With the Trinity test and the nuclear bombings of Hiroshima and Nagasaki in 1945 , and then subsequent nuclear weapons testing during the early years of the Cold War , background radiation levels increased across the world . Modern steel is contaminated with radionuclides because its production uses atmospheric air . Low-background steel is so-called because it does not suffer from such nuclear contamination . This steel is used in devices that require the highest sensitivity for detecting radionuclides
Trinity test
Trinity (nuclear test)
Low-background steel