W62 / Mk12

On August 12, U.S. Secretary of Energy Steven Chu announced that the Department of Energy’s National Nuclear Security Administration (NNSA) had dismantled the last W62 nuclear warhead. The final W62 dismantlement took place on August 11, 2010 at NNSA’s Pantex Plant outside Amarillo, Texas. Completed a full year ahead of schedule, the W62 dismantlement program safely and securely took apart the retired 1970s era warhead, never to be again a part of the U.S. nuclear weapons stockpile.

Some of the W87 Peacekeeper warheads will be redeployed on Minuteman ICBMs under the Safety Enhanced Reentry Vehicle (SERV) program. Each W87 warhead will displace one W62, or three W78 warheads currently deployed on Minuteman. The W62 will be retired by the end of Fiscal Year 2009.

In response to US plans to extend the stockpile deployment of the W62/Mk12 weapon, the ICBM Warheads Project Officers Group initiated a joint DoD/DOE study to identify options to keep the weapon well beyond its original design life and to specify upgrades to meet modern safety standards. Five design options, ranging from minimum modifications to the DoD and DOE components to an extensive redesign of the weapon, were described. The study was successfully completed and published by DOE/AL in March 1997.

The W62, a warhead used by the Air Force on the Minuteman III missile, was flight-tested six times (of the eight planned) between 1992 and 1996. Two planned tests were not conducted because DOE's Pantex facility had trouble preparing warheads for flight testing and could not deliver the test warheads to the Air Force in time for the test flights. Flight tests involve the actual dropping or launching of a weapon from which the nuclear components have been removed. DOE uses specially designed equipment-referred to as telemetry packages-to test the integration and functioning of the weapon's electrical and mechanical subsystems.

Future flight tests of the W62 warhead could also be limited by a lack of telemetry packages. Initially, DOE had enough telemetry packages to test this warhead during its projected life. However, retirement of this warhead has been delayed, and DOE is running out of telemetry packages. Also, the company that produced the package has gone out of business. DOE studied the possibility of using parts from W68 warhead telemetry packages (the W68 has been retired, but telemetry parts remain that may be recertified for use in the W62) to increase the number of telemetry packages available. If this is done, DOE could test W62 warheads for 4 years at the rate of two per year.

Eight of the nine weapons in the current stockpile are not as safe and secure as they could be made. Only the W84 nuclear warhead is equipped with all of the safety and surety features available. The other eight designs do not incorporate all of the safety and surety features that are available. The W62, in fact, did not have any safety features.

Air Force regulations prohibit air transport of nuclear weapons containing conventional high explosives (CHE), (i.e., B53, W62, W78) unless ground transport is not feasible. Air transport of CHE weapons requires approval by the Secretary of the Military Department or the Commander of the Unified or Specified Command or their designated representatives.