That's why low background steel isn't as much in demand as it used to be. It helps that it's easier to make it from scratch by filtering the air better. Even s

That's why low background steel isn't as much in demand as it used to be. It helps that it's easier to make it from scratch by filtering the air better. Even so, there are still some rare cases where it's easier to use older steel to ensure that there is much lower background radiation. Co-60 isn't the only source of radiation, and even 1/1,000th of peak levels can still be fairly high for applications like neutrino detectors.