Operation Castle
Design and development originated when Los Alamos National Laboratory proposed that a bomb design using lithium deuteride with non-enriched lithium was possible. The new design was designated TX-17 on February 24, 1953. The TX-17 and 24 were tested as the "Runt" (Castle Romeo shot) device during Operation Castle in 1954. After the successful tests, basic versions of the Mk 17 and 24 were deployed as part of the "Emergency Capability" program.