OT: Clean steel? additional ramblings

Sellam Ismail was asking about "clean steel", here is some of what I know/remember from one of the applications that require it. The trace amounts of radioactive "stuff" in the new steel can swamp out the radioactive particle counters on some experiments. There was an experiment at the University of Missouri to look at the muscle/fat percentages in humans and in cows. There was an especially built building made from "old battleship steel" that enclosed the radioactive particle counter. The "experimental subject" was given trace amounts of radioactive potassium which would be incorporated into their muscle. The entire subject was then placed in a whole body detector to determine the percentage of the body mass that was muscle versus fat. I heard that they had gotten the steel from an old sunken ship. may be entirely myth Thanks Mike