Guidelines for effective radiation transport for cable SGEMP modeling

Technical Report · Tue Jul 01 04:00:00 EDT 2014

DOI:https://doi.org/10.2172/1322291· OSTI ID:1322291

Drumm, Clifton Russell ^[1]; Fan, Wesley C. ^[1]; Turner, C. David ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

This report describes experiences gained in performing radiation transport computations with the SCEPTRE radiation transport code for System Generated ElectroMagnetic Pulse (SGEMP) applications. SCEPTRE is a complex code requiring a fairly sophisticated user to run the code effectively, so this report provides guidance for analysts interested in performing these types of calculations. One challenge in modeling coupled photon/electron transport for SGEMP is to provide a spatial mesh that is sufficiently resolved to accurately model surface charge emission and charge deposition near material interfaces. The method that has been most commonly used to date to compute cable SGEMP typically requires a sub-micron mesh size near material interfaces, which may be difficult for meshing software to provide for complex geometries. We present here an alternative method for computing cable SGEMP that appears to substantially relax this requirement. The report also investigates the effect of refining the energy mesh and increasing the order of the angular approximation to provide some guidance on determining reasonable parameters for the energy/angular approximation needed for x-ray environments. Conclusions for γ-ray environments may be quite different and will be treated in a subsequent report. In the course of the energy-mesh refinement studies, a bug in the cross-section generation software was discovered that may cause underprediction of the result by as much as an order of magnitude for the test problem studied here, when the electron energy group widths are much smaller than those for the photons. Results will be presented and compared using cross sections generated before and after the fix. We also describe adjoint modeling, which provides sensitivity of the total charge drive to the source energy and angle of incidence, which is quite useful for comparing the effect of changing the source environment and for determining most stressing angle of incidence and source energy. This report focusses on cable SGEMP applications, but many of the conclusions will be directly applicable for box Internal ElectroMagnetic Pulse (IEMP) modeling as well.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Science (NA-113)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1322291
• Report Number(s): SAND2014--15576; 607343
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
97 MATHEMATICS AND COMPUTING
APPROXIMATIONS
CHARGED-PARTICLE TRANSPORT
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CROSS SECTIONS
DEPOSITION
ELECTRIC CABLES
ELECTRIC CHARGES
ELECTRONS
EMISSION
ENERGY RESOLUTION
INCIDENCE ANGLE
INTERFACES
INTERNAL ELECTROMAGNETIC PULSES
MESH GENERATION
PHOTON TRANSPORT
PHOTONS
RECOMMENDATIONS
S CODES
SENSITIVITY
STRESSES
SURFACES
X RADIATION