On April 6, 1993, in the Plutonium Facility at the Lawrence Livermore National Laboratory (LLNL), a glove box worker detected contamination on the palm of one hand after performing a weekly task. He was replacing the drying agent in a cylinder that removes moisture from a gas stream passing through it. The function of the plutonium facility at LLNL is to perform nuclear design for the Department of Energy and Department of Defense (ORPS Report SAN--LLNL-LLNL-1993-0027).
Two workers were present in the room at the time. One had been unscrewing the top of the cylinder inside the glove box at Work Station 4505 in order to replace the drying agent. After completing this task he removed his hands, intending to move on to a set of adjacent glove boxes. Before doing so, he monitored his gloved hands and detected contamination on the surgeon's gloves he was wearing. He removed the gloves and put on a new pair. He then also installed port covers on the glove ports of the box he had just been working on, because he believed that the glove box was leaking, and he wanted to prevent the spread of contamination.
He then monitored his hands again and detected contamination on the new pair of surgeon's gloves. He discarded the gloves and then detected contamination on the palm of his right hand. At this point he summoned health and safety technicians and a hazard control supervisor. A complete radiation survey detected contamination only on the individual's palm, but none on the front of the glove box or the floor under it. The employee's palm was successfully cleaned to below detectable levels and nose wipes were collected for a bioassay. Preliminary data shows no detectable internal contamination.
The box gloves at this work station were then replaced. A visual examination during the change-out showed a small hole in the right hand palm. Investigators examining this incident noted that the lid on the cylinder was sticking and required considerable torque to unscrew it. The lid is knurled to provide a gripping surface. The investigators concluded that two possible scenarios could account for this contamination: (1) The force involved in unscrewing the lid may have caused a puncture of both gloves (box glove and surgeon's glove) and resulted in contamination of the skin, or, (2) A hole in the box glove may have caused contamination to the first surgeon's glove, which was then transferred to the employee's palm when he changed to a new set of surgeon's gloves. In retrospect, the worker should have monitored the skin surface of his hands immediately after detecting contamination on the first set of gloves.
Two lessons to be learned from this incident are that caution must always be exercised when twisting or torquing components in a glove box work environment, and that, once one barrier has been breached allowing contamination to spread, a complete evaluation should be performed before proceeding with the work in hand.