The B61 bomb: A case study in costs and needs

The B61 provides a case study in the expense and innovations driving the ambitious effort to maintain the nation’s nuclear defenses at a time of fiscal constraints and a shift away from reliance on nuclear deterrence.

The most versatile in the stockpile

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A glimpse at the aging nuclear stockpile and the rising budget

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View the technologies behind nuclear testing

Sandia National Laboratories is the engineering center of the U.S. nuclear weapons complex, a sprawling collection of labs and warehouses at Kirtland Air Force Base on the eastern edge of Albuquerque. Sandia’s primary mission is ensuring the safety, security and reliability of the nuclear arsenal.

Inside one of those warehouses, on a gray-painted floor, sits a full-scale replica of the B61. The model is where young engineers and nuclear maintenance technicians learn to care for the aging weapon. A preflight control panel displays the commands that technicians are trained to carry out: “Delivery/Option/Delay” and “Strike Enable” to detonate the fearsome bomb.

The device looks simple, but its appearance is deceptive. Inside are 6,500 parts, making the bomb one of the most complex weapons in the arsenal. The firing mechanism alone has 400 components.

Built to withstand supersonic speeds, the B61 is the most versatile weapon in the stockpile. It can be carried long distances by a wide number of aircraft, from a B-2 stealth bomber flying from a base in Missouri to North Korea or China to an F-16 or Tornado jet fighter flying to Russia from a NATO base in Europe.

The versatility extends to the explosive power. Different variations produce different yields, the “dial-a-yield,” or DAY. Depending on the warhead, the president could choose an explosion slightly less powerful than the one that destroyed Hiroshima in 1945, or he could dial it up to a thermonuclear blast 30 times as strong.

The B61 can be dropped free-fall or with a parachute, detonated in the air or on the ground. Its Kevlar parachute, wrapped so tightly it is as hard as an oak tree’s trunk, can slow the bomb’s descent speed from 1,000 mph to 35 mph.

Five versions are still in service. The latest is the B61-11, activated in the mid-1990s as the only ground-penetrating nuclear weapon, known as the “bunker buster.” It is designed to reach hardened bunkers buried far underground and to detonate its nuclear payload on a time delay.

As the most modern version, the bunker buster will escape renovation. The other four models will be collapsed into a single version, an experiment never tried before, according to nuclear weapons experts.

Tight deadline for reinvention

Modernizing a nuclear weapon is not like upgrading any other machine. In the automobile industry, for example, cars are improved each year to reflect the latest technological advances and design changes. By contrast, few of the B61’s major components have been rebuilt to 21st-century, digital-age standards.

Most of the new components will not be replacements. They will be completely new, state-of-the-art versions, designed and built with equipment that did not even exist when the first iterations were turned out in the mid-1960s. “The entire arsenal was built with less computational power than what’s inside an iPhone,” one weapons manager said.