Abstract
The ability to accurately model the subsurface transport of radionuclides is fundamental to the remote detection and characterization of underground nuclear explosion (UNE) events. Developing more sophisticated transport models presents a significant opportunity to enhance monitoring capabilities, particularly in the reliable prediction of signature migration. Experimentally determined characterization of geologic materials associated with transport properties is the pertinent base information for such robust model development and calibration. Here, we report results from an unprecedented study demonstrating changes to the pore and fracture network structures in geological materials in response to UNEs over nanometer to micrometer length scales. Volcanic tuffs of five different lithological formations from pre- and post-UNE environments were collected from the Nevada National Security Site. Combined ultra-small and small-angle neutron scattering techniques were used to characterize the tuff pore structure. The results demonstrate measurable differences in the specific surface area and porosity of samples pre- and post-shot from texturally similar lithological formations, indicating that pore properties can serve as a direct physical signature of a UNE. The results also provide experimentally determined transport parameters in support of advanced model development through the integration of gas migration, hydrodynamic simulations, and geologic framework models.
Data availability
The datasets generated and/or analyzed during the current study are available in the Zenodo repository, https://doi.org/10.5281/zenodo.17613298.
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Acknowledgements
This Low Yield Nuclear Monitoring (LYNM) research was funded by the National Nuclear Security Administration, Defense Nuclear Nonproliferation Research and Development (NNSA DNN R&D). The authors acknowledge important interdisciplinary collaboration with scientists and engineers from LANL, LLNL, NNSS, PNNL, and SNL. This work was supported by the U.S. Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001). Samples were collected and analyzed as part of the Underground Nuclear Explosion Signatures Experiment (UNESE). UNESE was created to apply a broad range of research and development (R&D) techniques and technologies to nuclear explosion monitoring and nuclear nonproliferation. It was a multi-year research and development project sponsored by the NNSA DNN R&D, and was collaboratively executed by Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Mission Support and Test Services, Pacific Northwest National Laboratory, and Sandia National Laboratories. The authors acknowledge the Center for Neutron Research (CNR) at National Institute of Standards and Technology for access to Small Angle Neutron Scattering (SANS). Access to Ultra-Small Angle Neutron Scattering (USANS) was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249.
Funding
Funding for this project was provided by the National Nuclear Security Administration’s Office of Defense Nuclear Nonproliferation Research and Development (NNSA DNN R&D).
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M.D. and R.P.H. conducted SANS experiments and analysis and wrote the first draft of the manuscript. M.E.H. conducted SANS experiments. A.J.S., S.T.B., and J.E.W conducted supporting sample analysis. J.G.B. supported SANS experiments. E.M.S. contributed to writing the manuscript. C.W.N. finalized the manuscript and prepared Figs. 2, 3, 4, 5, 6, 7 and 8. All authors reviewed the manuscript.
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Ding, M., Hjelm, R.P., Hawley, M.E. et al. Characterization of volcanic tuff pores pre- and post-underground nuclear detonation using ultra-small and small angle neutron scattering. Sci Rep (2026). https://doi.org/10.1038/s41598-026-40996-4
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DOI: https://doi.org/10.1038/s41598-026-40996-4
