US ships 100 upgraded B61-12 nuclear bombs to Europe

The B61-12 has a nuclear warhead with four selectable power options at launch depending on the target to hit. It has the ability to penetrate underground, exploding deep to destroy command center bunkers and other underground structures. The Pentagon’s program foresees the construction of about five hundred B61-12 with an estimated cost of roughly 10 billion dollars (so each bomb will cost double what it would cost if it were built entirely of gold).

Design Features

Two stage radiation implosion weapon.

Light weight, intermediate yield bomb with variable yield options ("dial-a-yield" or DAY), and flexible fuzing and delivery options. Designed for high-speed external carriage and low altitude delivery. Modular weapon system design.

Contains two neutron generators (supplied by General Electric).

Spin stabilized by rocket. 24 ft. Nylon/Kevlar-29 ribbon parachute ejected by gas generator. Allows rapid deceleration from supersonic velocity (only 2 seconds required to decelerate to 35 mph). Tested at up to Mach 1.2.

The lowest yield option for the B61 (the same for all tactical mods) is 300 tons which probably represents the basic unboosted yield of the fission primary.

The B61 has four major sections:

-Nose Subassembly: contains a dual-channel radar airburst fuze and two piezoelectric crystal impact fuzes, and shock mitigating material for laydown delivery.

-Center Warhead Subassembly: "hard case" containing the actual thermonuclear warhead, sealed and desiccated with polyurethane spacers to support warhead and provide shock isolation. Also contains thermal batteries, safeties, and firing circuits.

-Rear Subassembly: Preflight arming controls, fuzing option switches, safe separation setting dials, and spin rockets for free fall weapon stabilization.

-Tail Subassembly: consists of bomb fins, afterbody structure, parachute with associated deployment and release mechanisms. Complete parachute assembly weighs 115 lb.

Current models are made up of 6000 parts in 1800 subassemblies, manufactured by 570 suppliers and 9 principal contractors.

Features of individual models currently in stockpile:

-Mod 3: Tactical bomb with 4 yield options - 0.3 Kt, 1.5 Kt, 60 Kt, and 170 Kt. This is the highest yield tactical bomb mod. Along with the mod 4, this was the first mod developed using PBX-9502 IHE, and the first to be equipped with a microprocessor based arming and firing system (in 1980).

-Mod 4: Tactical bomb with 4 yield options - 0.3 Kt, 1.5 Kt, 10 Kt, and 45 Kt.

-Mod 7: Strategic bomb with multiple yield options - lowest is 10 Kt, highest is 300 Kt. This is a converted Mod 1 bomb. The conversion replaced the earlier PBX-9404 HE with PBX-9502 IHE. It has the highest yield of any B61 family weapon (including other warhead derivatives, like the W-80).

-Mod 10: Tactical bomb with 4 yield options - 0.3 Kt, 5 Kt, 10 Kt, and 80 Kt. Converted W-85 Pershing II missile warhead.

-Mod 11: Tactical or strategic bomb with multiple yield options presumably ranging from 10 Kt (and possibly lower yields) to 340 Kt. This is a modified Mod 7 with a one-piece case hardened steel center case, and a new nose piece and rear subassembly to provide ground penetration capability for defeating buried targets ("bunker busting") . The parachute assembly has also been removed, and new aerodynamic fins added for high-velocity, accurate delivery. The B61-11 buries itself 3-6 meters underground before detonation, transfering a much higher proportion of the explosion energy to ground shock, compared to surface bursts. The actual warhead itself is identical to the Mod 7. This is the first new model of a U.S. warhead to go into service since warhead production was suspended in 1989. It is being produced by field modification of existing Mod 7s.