[2] The MET was the first bomb core to include uranium-233 (a rarely used fissile isotope that is the product of thorium-232 neutron absorption), along with plutonium; this was based on the plutonium/U-235 pit from the TX-7E, a prototype Mark 7 nuclear bomb design used in the 1951 Operation Buster-Jangle Easy test.

It produced a yield of 22kt (comparable to the Fat Man plutonium-only weapon that exploded over Nagasaki), but significantly less than the expected amount.

However, weapon designers at Los Alamos substituted the experimental core without notifying the DoD.

[3][4] The Civil Defense Apple-2 shot on May 5, 1955 was intended to test various building construction types in a nuclear blast.

A short film about the blast, referred to as "Operation Cue", was distributed by the Federal Civil Defense Administration.