NUCLEAR WEAPONSScorpius Images to Test Nuclear Stockpile Simulations
One thousand feet below the ground, three national defense labs and a remote test site are building Scorpius — a machine as long as a football field — to create images of plutonium as it is compressed with high explosives, creating conditions that exist just prior to a nuclear explosion. The Sandia injector is key to validating plutonium pit performance.
One thousand feet below the ground, three national defense labs and a remote test site are building Scorpius — a machine as long as a football field — to create images of plutonium as it is compressed with high explosives, creating conditions that exist just prior to a nuclear explosion.
These nanosecond portraits will be compared with visuals of the same events generated by supercomputer codes to check how accurately the computed images replicate the real thing.
“It’s clear we need to know that the stockpile will work if required,” said Jon Custer, Sandia National Laboratoriesproject lead. “Before President Bush’s testing moratorium in 1992, we knew it did since we were physically testing. Now we have computer codes. How well do they predict what really happens? Do we have accurate data we put into the codes? To answer these questions with higher fidelity, we need better experimental tools, and Scorpius is a major new experimental tool.”
The $1.8 billion project, combining the expertise of researchers from Sandia, Los Alamos and Lawrence Livermore national labs with support from the Nevada National Security Site — a test area bigger than the state of Rhode Island — is expected to be up and running by late 2027.
Tickling the dragon’s tail
“We intend to use Scorpius’ actual images, gained from what we call ‘tickling the dragon’s tail,’ to check our computer simulations,” Custer said. “These simulations theoretically describe the hydrodynamics of plutonium in its various states, and we want to see how closely they match.”
Hydrodynamics here refers to material compressed and heated with such intensity that it begins to flow and mix like a fluid.
Tickling the dragon’s tail in this case means designing experiments that approach but stay below the threshold of criticality — that is, always subcritical, involving less than the mass needed for an explosion — while enabling a study of plutonium in that highly compressed and thermally heated state.
Above-ground facilities have tested the explosive behaviors of surrogate materials, but the inherent differences with plutonium cannot be accurately accounted for. While Scorpius will produce X-ray images during full-scale testing of plutonium, facilities that are equivalent but above-ground, including the Dual-Axis Radiographic Hydrodynamic Test Dual-Axis Radiographic Hydrodynamic Test machine at Los Alamos, instead must use implosionlike episodes to test the behaviors of surrogate materials.
