TAM-E - AAHP Special Session Part 1 Baltimore 1-2 08:00 - 12:00
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| Chair(s): Charles Potter, Heather Pennington
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TAM-E.1
08:00 Introduction to Radiation Dispersal and Consequences CA Potter*, Sandia National Laboratories
Abstract: This presentation serves as an introduction to the American Academy of Health Physics special session on radiological dispersal and consequences. A concern about the loss of materials due to accidents in Goiania, Brazil; Ciudad Juárez Mexico; and other locations resulted in a conference by the International Atomic Energy Agency in 1998 that highlighted the consequences and identified further actions. Since that conference, research has been conducted across the breadth of the subject and this session highlights both the physics of dispersion of radioactive material and the consequences of such dispersion. Terrorists have shown an interest in the radiological threat, focusing on radiation dispersal as a preferred method for areal denial and related consequences. The special session will touch on all of these aspects.
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TAM-E.2
08:45 RDD risk – A holistic model for radiological facilities S Rane*, Sandia National Laboratories
; J Harris, Purdue University; C Potter, Sandia National Laboratories
Abstract: The widespread use of radioactive materials worldwide for industrial, medical and academic purposes has led to an increasing concern about loss, theft and sabotage of radiological devices and facilities. Loss of control or theft of such radioactive materials, in risk-significant quantities, could lead to their use for malicious purposes in making a radiological dispersal device (RDD) or a radiological exposure device (RED). Of the many radioactive materials available, three that are generally found in healthcare facilities are considered the most attractive candidates for use in RDDs: Co-60 (radiosurgery devices), Cs-137 (blood irradiators) and Ir-192 (brachytherapy HDR devices). Such RDDs appeal to terrorists because they require limited technical knowledge to build and deploy as compared to nuclear devices. The Potential Facility Risk Index (PFRI) models the RDD risk as a triplet of threat, vulnerability, and consequences. The threat component is devised as a utility function weighing the radioactive material asset preference and the threat group attributes. The principles of probabilistic risk assessment, pathway analysis and statistical analysis are implemented to account for radioactive material theft probabilities in different attack scenarios. Locational hazards and nuclear security culture are measured as a function of radiological facility vulnerability. The consequences of the RDD are examined as a function of immediate fatalities from the blast and radiation, injuries from the blast, morbidity from stochastic effects, and the economic loss resulting from decontamination costs, evacuation costs, business losses, and property loss. The PFRI ranges from “very low risk” (1) to “very high risk” (10) – a risk metric that may be used by decision makers to evaluate any security upgrades and justify security investments.
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TAM-E.3
09:30 Break
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TAM-E.4
09:45 Radiological Dispersal Parameters HM Pennington*, Sandia National Laboratories
Abstract: This presentation provides a review of particle sizes, settling velocity, and how both impact the deposition and spread of material. Different possible driving mechanisms will be discussed, including explosive, mechanical, and passive. For explosive dissemination, important parameters that affect dispersal are the explosive type, as well as quantity and radiological material parameters of chemical composition and physical properties. Mechanical driving methods such as techniques found in commerce to disperse material will be discussed. Parameters to consider for mechanical dissemination are the radiological material physical properties (e.g., solid, liquid, and gas). Passive dispersal will be discussed broadly, which may include dispersion using wind or water.
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TAM-E.5
10:30 Chemical Analysis of Cesium Chloride Sealed Sources D Abrecht*, Oak Ridge National Laboratory
; A Fuhr, Oak Ridge National Laboratory; C Weber, Oak Ridge National Laboratory
Abstract: The decay of 137Cs in CsCl sealed sources presents safety and handling risks due to the changing oxidation potential inside the capsules. A previous study examined the equilibrium thermodynamics and concluded that a vaporization release of radioactive material could occur if the capsule were breached and exposed to air. Because the previous study was a worst-case scenario, a follow-up study is being conducted which examines transient heat transfer and chemical reactions to more precisely define the risk and to help identify mitigation strategies. This new work encompasses two main tasks: 1) a more concise transient analysis of the bulk capsule behavior, and 2) theoretical calculations of molecular-level behavior during the conversion of a 137Cs atom to 137Ba. A brief review of the original study will be given and supplemented with up-to-date results from the current work.
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TAM-E.6
11:15 Evaluation of the Radioactive Material Release in the Harborview Research and Training Building and Implications for Emergency Response SV Musolino*, Brookhaven National Laboratory
; FT Harper, Neo Prime Risk Management Solution, LLC; J Schwantes, Pacific Northwest National Laboratory; EC Buck, Pacific Northwest National Laboratory; KP Carney, Idaho National Laboratory; DL Chichester, Idaho National Laboratory; DJ Murray, Idaho National Laboratory
Abstract: The objectives of the study were to assess the accidental release of CsCl at the Harborview Research and Center in Seattle for its implications related to emergency response methods. Ramifications of behavior and transport of CsCl dispersal within the building were evaluated, as well the phenomenology of this event compared to past alkali halide dispersal events. Data for the project were assembled from the Los Alamos National Laboratory Relativity data archive, data from the RAP response, a visit Seattle to see the site and locations of contamination and obtain samples for electron microcopy by the Idaho National Laboratory, interviews with personnel from the contractor preforming the remediation, data from the forensic study and electron microscopy by the Pacific Northwest National Laboratory, and 3D visualizations of the deposition data throughout the building. The complied data set was analyzed to estimate the particle size in the source term due to grinding. We then reconstructed the cesium transport through the numerous pathways throughout the building and quantified deposition on surfaces as a function of particle size. Sampling performed by standard methods for health and safety complicated the retrospective forensic type of analysis. Expansion of the relationship between Radiological Assistance Program and the Department of Energy forensics experts and use of alternate sampling methods would assist follow up studies beyond the initial sampling. It was recommended to expand sample protocols, archival, and document sample meta data and analytical results in RadResponder.
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