On September 12, 1995, a radiological specialist who was processing plutonium metal pieces in a glovebox in the Chemistry and Metallurgy Research facility at Los Alamos detected alpha contamination on her clothing. She removed the contaminated clothing, packaged it properly, and discarded it. A radiological control technician detected no other contamination on the specialist, from nasal smears, or in the area outside the radiological buffer. This event is significant because contamination migrated through the glovebox containment, and contaminated the specialist. (ORPS Report ALO-LA-LANL-CMR-1995-0019)
The specialist was cutting, polishing, and weighing samples of plutonium-239 metal in a glovebox. She wore a labcoat with sleeves taped, gloves, booties, and safety glasses for the work in accordance with standard procedure. The processing required her to use two separate sets of glovebox gloves within the train. She cut and polished a sample in one section of the glovebox train, transferred the sample to another section in the train, removed her hands from the first set of gloves, placed her hands in the second set of gloves, weighed the sample, and moved back to the first section. She repeated this process for each sample. She did not self- monitor her gloved hands each time she moved from one section of the glovebox to the other.
When her work was complete, she self-monitored her gloved hands and booties and found contamination on the palm of her right glove. A radiological control technician surveyed her for activity and assisted her in removing her labcoat and gloves. A survey of her personal clothing revealed alpha contamination. Radiological control technicians surveyed the area, finding contamination inside the right glovebox glove of both boxes. They found a one-inch tear in the forearm area of the right glovebox glove in the second set of gloves used by the employee. They determined that operations performed in the glovebox could not have caused the tear.
During the event critique, investigators found that a maintenance crew replaced the glovebox gloves before the contamination occurred and found no problems with the replacement gloves. The facility manager asked for an analysis of the methods of storing and installing gloves. Investigators found that the damaged glove was stored at the facility for at least two years before it was installed, and it was folded to save space, creasing the forearm area. When the radiological specialist extended the glove, it tore at the crease and contamination migrated through the tear. Because there was no monitoring instrumentation near the glovebox train, the employee did not self-monitor each time she removed her hands from a set of glovebox gloves and did not realize that her right anti-contamination glove was contaminated. Her labcoat had six-inch slits at the sides of the waist and when she brushed her labcoat with the contaminated glove near the slit, the contamination from the gloves migrated through the slit to personal clothing underneath.
Investigators determined that the direct cause of the occurrence was the glove failure. They established three management problems as the root cause. One, management did not realized the need for monitoring equipment near the glovebox train, resulting in an inadequate work environment. Two, management did not realize that labcoats with slitted sides are unsuitable as anti-contamination clothing. Three, management failed to establish a policy for storage of glovebox gloves.
The facility manager directed the following corrective actions.
- Complete an inventory of the glovebox gloves, checking for age and damage, repackaging or discarding as required.
- Mount survey instrumentation on radiological containment boxes where needed.
- Provide survey equipment until fixed equipment is installed.
- Prepare policy document that addresses packaging and storage of glovebox gloves and directs workers to tape over the slits in labcoats and coveralls.
- Train facility personnel on policy changes.
- Distribute lessons learned from this occurrence as required reading.
DOE/EH-0256T, Radiological Control Manual, Section 347, describes controls required for glovebox operations. Included in these controls are requirements that gloveboxes be inspected for integrity before use, and that glovebox users monitor their hands periodically during work.