On July 21, 1994, facility personnel at Los Alamos National Laboratory reported actuation of a continuous air monitor alarm in room 206, Building TA55. The alarm actuated as a result of airborne radioactivity released in adjacent room 207. Facility personnel had earlier determined that airflow in room 206 was unbalanced. Because room 207 had a higher level of airborne activity, they wanted air to flow from room 206 to room 207; instead, undesired air was passing from room 207 into room 206. Operations personnel who acknowledged the alarm on the facility control system computer notified the radiological control technician responsible for the room. The technician red-lighted both rooms, which were empty at the time of the alarm. The technician then proceeded to the affected area to investigate the occurrence after putting on full anti-c clothing and respiratory protection. (ORPS Report ALO-LA-LANL-TA55-1994-0021).
Personnel initially thought that the source of airborne radioactivity was glove box gloves in the room 207 trolley system. They had noticed elevated airborne indications on a fixed head air sample for room 207 a week before the continuous air monitor alarm, and believed it was caused by the raised contamination levels (60,000 dpm/100 cm2) monitored on the gloves. The gloves were replaced and the airflow corrected; however, the readings continued to be elevated. On July 22, 1994, a technician replaced the fixed head air sample filters, but several hours later a continuous air monitor alarm actuated in room 207. Three contract employees working in room 207 immediately evacuated it and were surveyed by radiological control technicians. They were free of contamination.
Facility personnel finally traced the source of the airborne radioactivity to defective window gaskets on the glove box while conducting resealing activities in room 207. An examination of inspection records for glove box gaskets and seals revealed that, in January 1994, the glove box had been evaluated as having gaskets in poor condition. A gasket inspection program provides for monthly inspections and categorizes the gaskets as good, fair, or poor. Replacement of these gaskets and others in the same condition is scheduled but has been delayed because a contractor capable of providing the required wrap around containment device has not been hired. Facility personnel anticipate that these gaskets will be replaced beginning late August 1994.
ONS reviewed the Occurrence Reporting and Processing System for similar occurrences at Building TA55 and found the following.
On March 1, 1993, a glove box operator detected contamination on the backside of a surgical glove he was wearing while working in room 207. The operator left the room and was surveyed by a radiological control technician. The technician detected no contamination on the operator and none of the continuous air monitor alarms actuated. A check of the fixed head air sample filters indicated no increase above normal levels. He found that the source of contamination was plutonium leakage between the air lock tunnel and the glove box caused by a ring gasket failure.
Investigators determined the root cause of this occurrence was defective design of the glove box gasket. At the time the gasket was installed, the method used was acceptable; but, over time, the gaskets showed a tendency to deteriorate from plutonium radiation and other chemical hazards. Corrective actions addressed this design deficiency by revising glove box standards to exclude gasket glove box connecting rings in air lock tunnels and developing and implementing a procedure for inspecting and replacing deteriorating gaskets, however, the gasket replacement section has not been fully implemented. (ORPS Report ALO-LA-LANL-TA55-1993-0007).
The event discussed in this article underscores the importance of managers ensuring that a program to monitor a component part with demonstrated potential design defects is coordinated with aggressive pursuit of a contractor qualified to perform services required for component part replacement. DOE 4330.4A, Maintenance Management Program, chapter II, section 7, provides guidance for planning, scheduling, and coordinating maintenance activities. Section 10.1 in chapter II states the following.
Services are periodically needed to provide unique or supplementary maintenance support. An effective procurement process should be developed in accordance with the Quality Assurance requirements ... to ensure that parts, materials, and services are available when needed.