Threat Identification Parameters for a Stolen Category 1 Radioactive Source

Ussery, Larry Eugene¹  Winkler, Ryan¹  Myers, Steven Charles¹ 

[1] Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

关键词: GAMMA SOURCES;    HEALTH HAZARDS;    DOSE RATES;    DISTANCE;    RADIATION DOSES;    SHIELDING;   

DOI  :  10.2172/1239072
RP-ID  :  LA-UR--16-20987
PID  :  OSTI ID: 1239072
Others  :  TRN: US1600552

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来源: SciTech Connect

【 摘 要 】

Radioactive sources are used very widely for research and practical applications across medicine, industry, government, universities, and agriculture. The risks associated with these sources vary widely depending on the specific radionuclide used to make the source, source activity, and its chemical and physical form. Sources are categorized by a variety of classification schemes according to the specific risk they pose to the public. This report specifically addresses sources that are classified in the highest category for health risk (category 1). Exposure to an unshielded or lightly shielded category 1 source is extremely dangerous to life and health and can be fatal in relatively short exposure times measured in seconds to minutes. A Category 1 source packaged according to the guidelines dictated by the NRC and U.S. Department of Transportation will typically be surrounded by a large amount of dense shielding material, but will still exhibit a significant dose rate in close proximity. Detection ranges for Category 1 gamma ray sources can extend beyond 5000 ft, but will depend mostly on the source isotope and activity, and the level of shielding around the source. Category 1 sources are easy to detect, but difficult to localize. Dose rates in proximity to an unshielded Category 1 source are extraordinarily high. At distances of a few hundred feet, the functionality of many commonly used handheld instruments will be extremely limited for both the localization and identification of the source. Radiation emitted from a Category 1 source will scatter off of both solid material (ground and buildings) and the atmosphere, a phenomenon known as skyshine. This scattering affects the ability to easily localize and find the source.