Following the 1966 Palomares B-52 crash and the 1968 Thule Air Base B-52 crash , concerns were raised by accident investigators about the high explosive used in the nuclear devices , which had detonated on impact . Efforts were started to find an explosive that was stable enough to withstand the forces involved in an aircraft accident . The Lawrence Livermore National Laboratory developed the " Susan Test " — a standard test designed to simulate an aircraft accident by squeezing and nipping explosive material between metal surfaces of a test projectile . Following experiments with this device , the Los Alamos National Laboratory developed a new safer type of explosive , called insensitive high explosive ( IHE ) , for use in U.S. nuclear weapons
1968 Thule Air Base B-52 crash
1968 Thule Air Base B-52 crash
Insensitive munition