In its 13th semiannual report, released this week, the AEC told how it guards the U.S. against radioactive dust from its Nevada Proving Ground.
AEC weathermen, studying reports from as far away as Japan, postpone a test whenever they foresee conditions that might keep the dust from dissipating properly. Only once have they had misgivings. Early in 1952, they warned eleven people at the Groom mine, 20 miles from the firing area, to get out—quick. The dust settled down on schedule, but there was not enough of it to hurt anybody.
After each shot, AEC crews follow the wanderings of the dust as...