The National Nuclear Security Administration launched a series of experiments in 2023 with the goal of improving detection of low-yield nuclear explosions worldwide. One of the first experiments, Physics Experiment 1-A (PE1-A), involved a chemical explosion in a tunnel under the Nevada desert. Lawrence Livermore National Laboratory researchers compared computer simulations with data gathered from seismic, tracer gas, acoustic, and electromagnetic sources to further understand how nuclear explosions generate seismic waves.
The explosion, equivalent to 16.3 tons of TNT, took place at the Nevada National Security Site (NNSS) and was monitored by a variety of instruments. Seismic signals were recorded up to 250 kilometers away from the explosion site, providing valuable data for understanding the source physics of underground explosions. These experiments are part of a larger research program at NNSS, which has a history of nuclear testing dating back to the 1950s and 1960s, as well as more recent programs focused on non-nuclear chemical explosions.
The PE1 program includes seven new experiments involving underground chemical explosions under different conditions and atmospheric experiments to track gas transport. The program also utilizes a large electromagnetic coil to measure pulses of electromagnetic energy inside the tunnel, providing insight into how signals from underground nuclear tests may be affected by traveling through the earth. Researchers aim to validate their physics codes by piecing together signals from various experiments to create a more accurate simulation of nuclear explosions.
Advancements in high-performance computing have allowed researchers to create more realistic and complex explosion simulations. The heavily instrumented nature of the new experiments helps validate these simulations by providing high-resolution data sets for comparison. Atmospheric simulations must consider variables such as temperature changes and air turbulence under different conditions, and the experiments aim to understand how these factors affect the transport of gases released by underground tests. The seismic and acoustic data collected from PE1 will be made available to the public after two years, serving as a resource for the scientific community.
Overall, the experiments conducted under the PE1 program represent a significant step forward in improving the monitoring and understanding of nuclear explosions. By combining computer simulations with high-resolution data from a variety of sources, researchers are able to validate their models and gain insight into the complex physics of underground explosions. The information gathered from these experiments will contribute to global efforts to enhance detection capabilities and ensure the safety and security of nuclear testing worldwide.
