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The W-62 Warhead

Intermediate yield strategic ICBM MIRV warhead

Last modified 26 September 1997    Mk-12 RV mockup

The W-62 is the warhead used with the Mk 12 reentry vehicle which arms a portion of the Minuteman III ICBM force. Designed for use on MIRV (multiple independently targeted reentry vehicle) bus upper stage.

W-62/Mk-12 Warhead/Reentry Vehicle Package
Yield170 Kilotons
WeightWarhead/RV: 700-800 lb;
Warhead: 253 lb
LengthRV Body: 72 in;
Warhead: 39.3 in
DiameterRV Body: 21 in;
Warhead: 19.7 in
Number In Service610

Design Features

Two stage radiation implosion weapon.

RV CEP (circle error probability) is 900 feet

Known to be vulnerable to "hot" (high energy thermal) X-rays like those produced by thermonuclear ABM warheads.

Materials

Contains plutonium as primary fissile material
Fissile core is beryllium reflected
Deuterium-tritium boosted
Probably contains lithium-6 (95% enrichment) deuteride fusion fuel

Delivery Method

Minuteman III ICBM. Each missile carries up to three W-62s, and is based in a hardened underground silo.

Safeguards and Arming Features

Unknown

Fuzing and Delivery Mode

Unknown

Development

Designed and developed by Lawrence Livermore National Laboratory (LLNL)

W-62 Development Schedule
June 1964 Development engineering begun at LLNL
March 1967 Production engineering begun
March 1970 Quantity production begun
June 1976 Quantity production ends
April 1980 Retirement of early mods begun

Deployment

Initial manufacture March 1970
Initial deployment 1970 (first squadron of Minuteman III missiles went operational on 29 December). Between December 1979 and February 1983 900 W-62s were replaced by W-78/Mk-12As. Retirement of early mods began in April 1980, presumably the retirement consisted of W-62s that had been replaced by W-78s. Some of the remaining W-62s have been modified in program called Alt 903.
1725 W-62 warheads have been manufactured.
Currently in service: 610 warheads (the rest have been permanently retired)

Originally slated for retirement and dismantling under START II. 1995 Nuclear Policy Review reversed this and the W-62 is now destined for permanent retention in the enduring stockpile either in the ready "hedge" stockpile, or in the reactivatable "inactive " stockpile.