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Brookhaven National Laboratory had a minor radioactive contamination incident at the lab on Sept. 28, BNL officials have reported. The incident occurred during routine testing of monitoring equipment on the laboratory site, when a radioactive sealed source being used to test the monitoring equipment apparently leaked, according to George Goode, BNL assistant director for environment, safety and health. Two technicians conducting the testing were exposed to small amounts of radiation, Goode said. The level of exposure was not dangerous to their health and there were no off-site impacts, he said. The source of the contamination was a small brass rod into which radioactive cesium chloride is inserted, Goode said. The lab has 92 such source rods on site, he said. They are used to test the functioning of radioactivity monitors on the lab property. The rods, about eight inches long and a half-inch in diameter, are sealed and kept inside lead containers, he said. The lead container holding the leaky rod apparently tipped over inside a BNL pickup truck in which the two technicians were riding, Goode said. They righted the container and were unaware of the leak until later that day, when the contamination was detected by a radiation meter.
Investigators determined the source of the leak, and found contamination inside the cab of the pickup truck, on the hand of one of the workers and on both their shoes, Goode said. Radioactive contamination was also discovered in a parking lot, on stairs leading into a building at the lab and in the hallway of the building, apparently deposited by the workers' contaminated shoes. The floor mat of a private vehicle in which one worker later rode as a passenger was also contaminated, Goode said. Approximately six hours elapsed between the time the lead container tipped over inside the lab pickup truck, at about 10 a.m. and the discovery of the contamination at 4 p.m., Goode said. "Any time you have radioactivity where it's not supposed to be, it's not a good thing." Goode said. "We surveyed every office and every room in the building. We called people back in to test them. All the offices and all the people were clean." The worker who had a spot of contamination on his hand was not exposed to any danger, Goode said. A dose calculation to determine his exposure from the incident set it at 3.4 millirems, Goode said. The Department of Energy limit is 50,000 millirems, he said. According to the Nuclear Regulatory Commission, the average American is exposed to about 620 millirems each year. A chest X-ray results in an exposure of about 8 to 10 millirems per film, and a cross-country airplane flight results in a dose of 4 millirems.
But the standard set by the DOE is "as low as reasonably achievable," Goode said. "Whenever anybody gets a dose by accident, there's no correlating benefit," he said. "Any accident is treated seriously." All contaminated surfaces have been cleaned, Goode said. Nonporous surfaces were wiped clean and the contaminated asphalt will be cut from from the parking lot. The two technicians were tested for internal radiation uptake and tested at zero, Goode said. The investigation continues into why the source rod leaked and whether adequate measures are in place to test source rods stored and used at the lab, he said. The rod in question was at least 20 years old, according to the lab official. "There was certainly no off-site consequences. It was all localized to the paths of travel of these individuals. We have conducted hundreds of surveys of any place they could have been," Goode said. "We also went back through the log documenting the use of the source and checked every location where it had recently been used," he said. "An investigating committee is sequestered full-time and will issue a report by the end of the week," Goode said. "We are conducting a review of radiological operations throughout the whole lab, and of source use in particular," he said. "Pending the results of the investigation, laboratory director Sam Aronson will be standing-down radiological operations at the lab site in order to conduct a comprehensive review of all radiological policies, procedures, practices, and training programs," according to a statement issued by the lab. |
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