ONS reviewed two reports this week concerning positive indications that several subcontractors received an uptake of transuranic elements while working on decontamination and decommissioning at Argonne National Laboratory - East facilities.
On September 9, 1994, facility health physics personnel reported that seven contractor workers were internally contaminated while working on the Experimental Boiling Water Reactor decontamination and decommissioning project. The reactor was a demonstration plant used to illustrate the feasibility of boiling water reactors and has been shut down for more than two decades. The workers were involved with cutting the reactor vessel internals in the fuel pool. The area health physicist found minor tritium levels and americium-241 in bioassays made during exit processing of some of the workers. Health physics technicians collected additional urine samples from 25 Argonne National Laboratory and contractor personnel that six workers indicated positive bioassays plutonium-238 or americium-241. A fecal sample taken from the seventh worker indicated presence of americium-241. (ORPS Report CH-AA-ANLE-ANLEER-1994-0009)
In the second event, seven contractors received a positive indication from bioassay analysis upon completing the assigned scope of work in support of decontamination and decommissioning plutonium gloveboxes. The project plan required the workers to remove items from 61 gloveboxes, dismantle the boxes, and package them as low-level waste for shipment off site. Fecal samples taken from the workers upon termination indicated positive bioassays for americium-241 and plutonium-239/-240. However, analysis of urine samples indicated no evidence of a dose. All continuous air samples taken throughout the course of work were negative. Based on preliminary records, it appears likely that the 50-year committed effective dose equivalent for this intake will be less than 100 mrem. (ORPS Report CH-AA-ANLE-ANLEER-1994-0010)
Based on these two incidents, the laboratory management suspended all decontamination and decommissioning operations at Argonne National Laboratory - East. Managers established a high- level investigation committee that will convene soon to address issues related to all decontamination and decommissioning projects and provide corrective recommendations. ONS will provide additional information on these event in a future Weekly Summary.