Publications

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Facilities that manufacture, store or transport significant quantities of radiological material must protect against the risk posed by sabotage events. Much of the analysis of this type of event has been focused on the threat from a radiological dispersion device (RDD) or "dirty bomb" scenario, in which a malicious assailant would, by explosives or other means, loft a significant quantity of radioactive material into a plume that would expose and contaminate people and property. Although the consequences in cost and psychological terror would be severe, no intentional RDD terrorism events are on record. Conversely, incidents in which a victim or victims were maliciously exposed to a Radiological Exposure Device (RED), without dispersal of radioactive material, are well documented. This paper represents a technical basis for the threat profile related to the risk of nefarious use of an RED, including assailant and material characterization. Radioactive materials of concern are detailed in Appendix A.

A recent analysis of historical radionuclide resuspension datasets confirmed the general applicability of the Anspaugh and modified Anspaugh models of resuspension factors following both controlled and disastrous releases. While observations appear to have larger variance earlier in time, previous studies equally weighted the data for statistical fit calculations; this could induce a positive skewing of resuspension coefficients in the early time-period. A refitting is performed using a relative instrumental weighting of the observations. Measurements within a 3-d window are grouped into singular sample sets to construct standard deviations. The resulting best-fit equations produce tamer exponentials, which give decreased integrated resuspension factor values relative to those reported by Anspaugh. As expected, the fits attenuate greater error among the data at earlier time. The reevaluation provides a sharper contrast between the empirical models and reaffirms their deficiencies in the short-lived timeframe wherein the dynamics of particulate dispersion dominate the resuspension process.

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On October 27, I was invited to speak in front of the Subcommittee Coast Guard and Maritime Infrastructure of the Transportation and Infrastructure Committee of the US House of Representatives at a hearing entitled Prevention of and Response to the Arrival of a Dirty Bomb at a US Port. Sandia National Laboratories in New Mexico is recognized as having expertise in the general threat from radiological dispersal devices having led or participated in many studies on the topic, including a landmark study on dangers presented by the use of cesium chloride salts due to their solubility and associated dispersibility, and I have been working primarily in this area since 2010.

The RPID Project is implemented at all SNL facilities for activities involving the processing and/or storing of radioactive materials. Reference to SNL throughout this document includes all SNL facilities and activities.

The RPID Project will be implemented at all SNL facilities for activities involving the processing and/or storing of radioactive materials. This project includes activities at the Tech Area (TA) I, TA II, TA III, TA IV, TA V, Coyote Test Field, and environmental restoration sites at SNL, located in Albuquerque, New Mexico, and the Kauai Test Facility(SNL/KTF). Reference to SNL throughout this document includes facilities and activities at the Albuquerque location and at SNL/KTF.

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There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

An important paper by Skrable et al. included a retention function for compartment contents during a continuous intake, including the same time variable in both the numerator and denominator of the replacement function. In fact, the time in the denominator should have been represented as a constant describing the ultimate period length for the continuous intake, whether greater than, less than, or equal to the time variable for the associated measurement. Copyright © 2012 Health Physics Society.

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