Development of the weapon began in 1955 by Los Alamos National Laboratory , based on the earlier Mk 21 and Mk 46 weapons . In March 1958 the Strategic Air Command issued a request for a new '' ' Class C ' '' ( less than five tons , megaton-range ) bomb to replace the earlier Mk 41 . A revised version of the '' ' Mk 46 ' '' became the '' ' TX-53 ' '' in 1959 . The development TX-53 warhead was apparently never tested , although an experimental TX-46 predecessor design was detonated 28 June 1958 as Hardtack Oak , which detonated at a yield of 8.9 Megatons
Hardtack
Operation Hardtack I
B53 nuclear bomb