Operation Sandstone was a series of nuclear weapon tests in 1948 . It was the third series of American tests , following Trinity in 1945 and Crossroads in 1946 , and preceding Ranger . Like the Crossroads tests , the Sandstone tests were carried out at the Pacific Proving Grounds , although at Enewetak Atoll rather than Bikini Atoll . They differed from '' Crossroads '' in that they were conducted by the Atomic Energy Commission , with the armed forces having only a supporting role . The purpose of the Sandstone tests was also different : they were primarily tests of new bomb designs rather than of the effects of nuclear weapons . Three tests were carried out in April and May 1948 by Joint Task Force 7 , with a work force of 10,366 personnel , of whom 9,890 were military
Trinity
Trinity (nuclear test)
Operation Sandstone