Lawrence Livermore National Laboratory



Nuclear test shot.


Comparison of predicted (solid color areas) and measured (dashed colored lines) nuclear fallout from a historical nuclear test (yellow contours show areas of higher fallout; green to blue colors show lower fallout concentrations). (Courtesy of Peter Goldstein)

NARAC provides high-resolution atmospheric dispersion and fallout simulation capabilities for simulating nuclear detonations. Model fidelity is improved by enhancements or development of new models physics that treat:

  • Prompt effects from thermal radiation, ionizing radiation, and overpressure (developed in cooperation with Sandia National Laboratories)
  • Complete radionuclide inventories
  • Particle activity-size distributions, time-dependent buoyant cloud rise, and fallout fractionation (developed in cooperation with Oak Ridge National Laboratory)
  • Neutron activation products derived from LLNL’s Livermore Weapons Activation Code (LWAC)

Advanced physics models are used to produce more realistic fallout simulations in support of emergency response planning, consequence management, and nuclear forensics applications.