In the belly of the Bradbury Science Museum’s defense gallery sits a large cherry-red chamber that looks like an enormous gumball with a window. Although it has a playful appearance, it represents a very important process in maintaining the safety and effectiveness of aging nuclear weapons; it is a model of a Dual-Axis Radiographic Hydrodynamic Test (DARHT, pronounced “dart”) vessel.
Just like a car, as weapons age their parts start to break down and need to be refurbished or replaced. When the nation stopped underground testing of nuclear weapons nearly 30 years ago, scientists needed a new method to gauge the functioning of the aging nuclear stockpile in order to determine what materials needed updates or replacements. To do this in a securely contained manner, scientists developed the DARHT vessel to conduct explosive experiments.
Scientists detonate a modified weapon — analogous to one with a plutonium pit but carrying a replacement of non-nuclear metal incapable of creating a nuclear explosion — inside the vessel’s interior chamber. This keeps the test locked in a contained environment. The testers will take X-ray images of the detonation to produce data that can provide insight into the status of the stockpile.
The DARHT orb at the Bradbury is a replica of an actual vessel. The real deal is made of steel and weighs about 14,000 pounds, too hefty for the floor to hold.
In 2015, the Museum’s team reached out to the same company that fabricates the authentic DARHT vessels to help create the model. Following original designs and measurements, the fabricators were able to make a replica from wood and fiberglass. Blazing red in color, and measuring a life-sized 6 feet in diameter, the DARHT vessel is a striking centerpiece in the Bradbury’s exhibition space.
Check out our DARHT vessel replica and more when the Bradbury Science Museum reopens later this summer!