We examined the relative risk and impact of a dirty bomb employing Co-60 and Cs-137, the two most common high activity source materials. We found that the risk of an area denial dirty bomb attack is greater for Cs-137 due to the form and chemistry of CsCl, the soft, powdery salt form currently in use for high activity Cs-137 sources, found in blood and research irradiators.
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IEEE Transactions on Nuclear Science
HICUP models the angular dependent heavy ion upset cross section. It pulls together many of the parameters and concepts used to characterize the Single Event Upset (SEU) phenomena, unifying them in a single cohesive model. HICUP is based on a Rectangular Parallelepiped (RPP) geometry for the sensitive volume and the Weibull density function for the upset threshold energy. Excellent agreement is obtained between the model and heavy ion test data. HICUP is used to derive the correct scaling laws for transforming angular cross section data to normal incidence, reconciling two previously proposed inverse cosine scaling corrections. The angle-integrated HICUP model, I-HICUP, is used in Galactic Cosmic Ray (GCR) upset rate calculations with results nearly identical to the Space Radiation• code. Letaw [12] has procuced an automated SEU parameter fitting routine based on HICUP and the cH2 method. It ferrets out the best-fit critical SEU parameters embedded within the raw angular test data, including charge collection depth and funnel length. His method couples directly to the upset rate calculation in a self-consistent manner eliminating the need to arbitrarily assume a device depth. Results of this new procedure are presented. © 1995 IEEE
This report documents the reentry safety analyses conducted for the TOPAZ II Nuclear Electric Propulsion Space Test Program (NEPSTP). Scoping calculations were performed on the reentry aerothermal breakup and ground footprint of reactor core debris. The calculations were used to assess the risks associated with radiologically cold reentry accidents and to determine if constraints should be placed on the core configuration for such accidents. Three risk factors were considered: inadvertent criticality upon reentry impact, atmospheric dispersal of U-235 fuel, and the Special Nuclear Material Safeguards risks. Results indicate that the risks associated with cold reentry are very low regardless of the core configuration. Core configuration constraints were therefore not established for radiologically cold reentry accidents.