Explosives Safety and Hazard Mitigation

Fostering a safe environment for explosive manufacturing, assembly, and transportation

Simulation of explosive reaction. — Illustration depicting LLNL simulation of reactions in explosives.

For decades, LLNL’s scientists and engineers have studied ways to ensure the safety of our nation’s nuclear deterrent, including how the explosives used in these systems might respond to hazardous stimuli. We integrate highly diagnosed experiments with multi-physics modeling to understand and analyze threats posed by different hazard scenarios, such as those involving thermal and mechanical stimuli. This research underpins the safety of operations involving explosives, providing critical insight regarding the likelihood that a reaction will occur, the time-to-reaction following stimuli, and the severity of the reaction.

Advanced Diagnostics

We use flash x-ray radiography, high-speed optical imaging, microwave interferometry, and x-ray computed tomography to observe phenomenon that occur in a variety of hazard scenarios. This research enables us to better understand the underlying physics and chemistry, while providing a basis for developing new multi-physics models.

Mechanical Safety

We study how explosives respond to mechanical stimuli, such as the impact of projectiles, which can occur during manufacturing of charges. Focused experimental characterization informs the development of models, such as LLNL’s High Explosive Response to Mechanical Stimulus (HERMES) model, that enables us to predict the likelihood and severity of explosive reactions in different hazard scenarios.

Thermal Safety

We study how explosives respond to heating, which is especially relevant for fire scenarios. Under such conditions, we need to predict time-to-explosion to inform emergency planning. Lab-scale characterization informs LLNL’s multi-physics code, ALE3D, which includes thermal transport, chemical kinetics, and mechanical properties, to analyze thermal hazard conditions and develop risk mitigation plans.

Mission Impact

Our research provides the foundational knowledge that enables us to:

Support national security partners tasked with manufacturing, assembling, and transporting weapons systems—providing the safety basis for these hazardous operations and aiding efforts to adopt novel manufacturing processes.
Analyze the tradeoff between performance and safety, enabling design and production of inherently safer weapon systems.
Develop assessment tools that support efforts to enhance emergency response planning and mitigate hazards across the national security complex.

Research Highlights

The close coupling of highly diagnosed lab-scale experiments and predictive modeling powered by supercomputers enables LLNL scientists to enhance our understanding of hazards, develop mitigation strategies for existing explosives, and identify desired properties for new explosives. Examples of our research include:

Combining high-speed optical imaging with radiography to observe deflagration-to-detonation transitions in energetic materials. This research enables us to better understand the physics behind onset of reaction, pressurization, and deflagration phenomena.
Developing the all-venue HERMES model to study conditions that affect the severity of a reaction, as well as how an ignition event may expand or extinguish depending on the explosive type, extent of damage, and degree of confinement.
Developing the Dihedral Shear Compression test to study shear ignition under a variety of loading conditions, providing data used to improve the predictive capacity of the HERMES model.
Leveraging the capabilities of machine learning and artificial intelligence to scale reaction-rate models from microscale simulations, enabling us to determine the severity of shock-induced reactions.
Using genetic algorithms to optimize the calibration of chemical kinetics and shock initiation models to experimental data, which drastically reduces fitting time and improves accuracy compared to manual model calibration.
Conducting highly diagnosed lab-scale experiments to develop and validate thermal safety models of solid and fluid energetic materials, including thermal transport, phase changes, and chemical reactions. We use LLNL’s ALE3D code to simulate thermal hazard scenarios and recommend risk mitigation strategies.

Featured Collaborations

Our collaborations enable us to speed development of mission-relevant solutions. For example, we partner with:

The U.S. Army Research Laboratory, gaining insight from their experience building a multi-energy flash x-ray diagnostic, which enabled us to accelerate and optimize the design of LLNL’s flash computed tomography x-ray system.
Los Alamos and Sandia National Laboratories, as well as academic collaborators, to explore molecular dynamics simulations, grain-scale modeling, and mechanical safety modeling of explosives.
Academic institutions to perform research and development related to safety.

Related Resources

Scientists can capture and analyze data regarding three-dimensional detonation phenomena using our flash x-ray computed tomography system that produces 3-frame, 3D movies of dynamic events, including the ability to create a single-viewing-angle x-ray movie at frame rates of up to 100K frames per second. This capability is particularly useful for examining low-speed impact and deflagration-to-detonation transition phenomena.