Fermium
Albert Ghiorso and other scientists at the University of California, Berkeley first discovered fermium.  They found the element in the fallout from the explosion of the first successful hydrogen bomb test.  This test was on November 1, 1952.  In the fallout, scientists also discovered another new element, Einsteinium.  Because of the Cold War, the US military did not allow the scientists to publish their results in a scientific journal.  However, they conducted other studies and published their research in 1954.  The studies of nuclear fallout were declassified and published in 1955.