W74

Responding to a 1969 Army request for a replacement for the W48 155 mm artillery shell, Los Alamos started development of the W74. The reasons for the cancellation of the W74, were the obsolete technology and high cost. The weapon only employed fission, had no capability to be further developed as an "enhanced radiation" (neutron) device, The cost per shell would have approached $500,000 and just wasn't worth it. The development of the W74 was terminated in mid-1973.
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Unspecified drowning and submersion