Radiological Risk Assessment for King County Wastewater Treatment Division

Strom, Daniel J.

Pacific Northwest National Laboratory (U.S.)

关键词: Industrial Radiography;    Sewage Treatment Plant;    Cobalt-60;    Radioactive Materials;    Explosions;   

DOI  :  10.2172/935619
RP-ID  :  PNNL-15163 Vol. 1
RP-ID  :  AC05-76RL01830
RP-ID  :  935619

美国|英语

来源: UNT Digital Library

【 摘 要 】

Staff of the King County Wastewater Treatment Division (WTD) have concern about the aftermath of a radiological dispersion event (RDE) leading to the introduction of significant quantities of radioactive material into the combined sanitary and storm sewer system in King County, Washington. Radioactive material could come from the use of a radiological dispersion device (RDD). RDDs include "dirty bombs" that are not nuclear detonations but are explosives designed to spread radioactive material (National Council on Radiation Protection and Measurements (NCRP) 2001). Radioactive material also could come from deliberate introduction or dispersion of radioactive material into the environment, including waterways and water supply systems. This document develops plausible and/or likely scenarios, including the identification of likely radioactive materials and quantities of those radioactive materials to be involved. These include 60Co, 90Sr, 137Cs, 192Ir, 226Ra, plutonium, and 241Am. Two broad categories of scenarios are considered. The first category includes events that may be suspected from the outset, such as an explosion of a "dirty bomb" in downtown Seattle. The explosion would most likely be heard, but the type of explosion (e.g., sewer methane gas or RDD) may not be immediately known. Emergency first responders must be able to quickly detect the radioisotopes previously listed, assess the situation, and deploy a response to contain and mitigate (if possible) detrimental effects resulting from the incident. In such scenarios, advance notice of about an hour or two might be available before any contaminated wastewater reaches a treatment plant. The second category includes events that could go initially undetected by emergency personnel. Examples of such a scenario would be the inadvertent or surreptitious introduction of radioactive material into the sewer system. Intact rogue radioactive sources from industrial radiography devices, well-logging apparatus, or moisture density gages may get into wastewater and be carried to a treatment plant. Other scenarios might include a terrorist deliberately putting a dispersible radioactive material into wastewater. Alternatively, a botched terrorism preparation of an RDD may result in radioactive material entering wastewater without anyone's knowledge. Drinking water supplies may also be contaminated, with the result that some or most of the radioactivity ends up in wastewater.