Dual-Axis Radiographic Hydrodynamic Test Facility

Dual-Axis Radiographic Hydrodynamic Test Facility. It is a premier subcritical experiment and diagnostic facility located at Los Alamos National Laboratory in New Mexico. Operated for the National Nuclear Security Administration, its primary mission is to support the Stockpile Stewardship Program by providing essential data on the behavior of nuclear weapon materials without conducting live nuclear detonations. The facility uses powerful X-ray sources to capture dynamic, multi-angle images of imploding weapon mock-ups and other high-energy density physics experiments.

Overview

The facility is a cornerstone of the United States' post-Cold War science-based approach to maintaining the reliability and safety of its nuclear arsenal. It was constructed as a direct successor to earlier facilities like the PHERMEX at Los Alamos National Laboratory and the Cyclotron at Lawrence Livermore National Laboratory. By enabling detailed radiographic observation from two perpendicular axes simultaneously, it provides uniquely comprehensive data that is critical for validating sophisticated computer simulations, such as those run on the Advanced Simulation and Computing Program's supercomputers. This work is conducted under the auspices of the broader Stockpile Stewardship Program, which was established following the cessation of underground testing mandated by the Comprehensive Nuclear-Test-Ban Treaty.

Design and Capabilities

The core design features two identical, independent linear induction accelerator systems, each capable of producing a very intense, short pulse of high-energy X-rays. These accelerators, aligned orthogonally, fire through thick radiation shielding to image a central test chamber. Each axis utilizes advanced Bremsstrahlung sources and sophisticated detector arrays to capture radiographic images with exceptional temporal and spatial resolution. The entire system is synchronized with nanosecond precision to study extremely fast hydrodynamic events. This dual-axis configuration is a significant advancement over previous single-axis facilities, allowing scientists to observe asymmetries and three-dimensional effects in imploding systems that were previously inferred or modeled.

Hydrodynamic Testing

In a typical hydrodynamic test, a mock-up of a nuclear weapon pit, using surrogate materials like tantalum or depleted uranium, is imploded using high explosives. As the implosion proceeds at speeds exceeding several kilometers per second, the two radiographic axes capture multiple sequential images of the event. These images reveal the behavior of the materials under extreme pressure and density, providing direct evidence of performance. This data is indispensable for understanding issues related to aging in the stockpile, such as changes in high explosives or corrosion in metal components. The experiments are subcritical, meaning no self-sustaining nuclear fission chain reaction occurs.

Role in Stockpile Stewardship

The facility provides the essential experimental data required to anchor and validate the multi-physics computer codes used to model nuclear weapon performance. This validation is a fundamental pillar of the Stockpile Stewardship Program, ensuring confidence in the assessed safety and reliability of weapons like the B61 nuclear bomb and the W88 warhead without full-scale testing. Its work directly informs the annual Stockpile Stewardship and Management Plan reports to the United States Congress and the President of the United States. The data also supports the life extension programs managed by the National Nuclear Security Administration, such as those for the W76 and W80 warheads.

Facility History and Operations

Authorized in the early 1990s, construction of the facility began in 1995 and was completed in 1999, with the first successful dual-axis shot occurring that same year. Its construction was a major project within the broader Accelerated Strategic Computing Initiative. The facility operates under a rigorous operational schedule, conducting numerous experiments annually that are planned and analyzed by teams from Los Alamos National Laboratory, Sandia National Laboratories, and Lawrence Livermore National Laboratory. Its continued operation and upgrades are considered vital to the long-term success of the Stockpile Stewardship Program, ensuring the United States can maintain its nuclear deterrent under the guidelines of the Treaty on the Non-Proliferation of Nuclear Weapons.

Category:Los Alamos National Laboratory Category:United States Department of Energy national laboratories Category:Nuclear weapons infrastructure of the United States