Decades of detonators

For fourscore years—or eighty, as we’d say today—Los Alamos National Laboratory has designed and produced the detonators for nuclear weapons. 

“Los Alamos has been making detonators since the Manhattan Project,” says Daniel Mendoza, the Detonator Production division leader. “Detonators are extremely important. Without them working very precisely and reliably, you do not have a functioning nuclear weapon.”

In an implosion-method nuclear weapon, the core (or pit) that contains nuclear material is surrounded by high explosives. Detonators set off the high explosives, causing the weapon core to compress and generate a nuclear reaction. To ensure this implosion happens evenly, the detonators around the core must go off at exactly the same time.

During the Manhattan Project, scientists designed detonators that used an electrical charge from a capacitor to heat and explode a hair-thin wire inside the detonator, setting off a small amount of explosive inside the device. These detonators, called exploding bridgewire detonators, were used in the Gadget (detonated at the Trinity site) as well as in the Fat Man and Little Boy devices used to bring about the end of World War II. Although exploding bridgewire detonators are still made and used for some purposes, the Lab has developed new detonator designs over the years.

One new detonator is called a chip slapper. Chip slappers work similarly to exploding bridgewire detonators, but they allow for increased separation of the electrical components from the explosive, thus improving safety. Chip slappers have replaced exploding bridgewire detonators in some modern nuclear weapons.

The Lab is also building detonators that use optical energy instead of electricity to set off the explosion. “Rather than having an electrical pathway to detonation, an optical detonator relies on a small, robust laser, removing all electrical means of detonation,” says Mike Bowden, leader of the Lab’s Optical Initiation Technology Readiness team. “The greatest challenge in developing optical detonators is delivering the energy from the laser to the detonator. We use optical fibers for this. The result is the safest and most reliable detonators ever made.”

Following World War II, detonators continued to be designed by scientists at Los Alamos, but production moved to Mound Laboratories in Ohio. In 1989,  production capability returned to Los Alamos and has been a key part of the Lab’s mission ever since. 

Bowden says he often reflects on the fact that he is following in the footsteps of the designers who created detonators during the Manhattan Project. “When I think about the historical significance and scientific importance of these tiny devices, I feel honored to be part of Los Alamos’ 80-year commitment to national security.” ★