On January 19, 1993, personnel at the Los Alamos Nuclear Materials Processing- Nitrate Systems Facility (NMT-2) attempted to clear debris from argon flow lines connected to a reaction chamber inside a glovebox. The debris was left over from previous use of the system. When the argon flow lines were purged with argon gas, the Continuous Air Monitor (CAM) alarms in the room sounded. The personnel evacuated to the corridor outside the room, and health physics staff performed contamination surveys including nose swipes on the eight people who had been in the room. Swipes from two of the eight yielded nostril readings from 44dpm to 997 dpm alpha. The health physics personnel placed these two people on "Prompt Action" urine and fecal sampling procedures to evaluate their condition. They were to remain under evaluation for one year. Health physics did not find any skin or clothing contamination. A survey of the room detected up 100,000 dpm per 100 cm2 on a laser window in the glove box wall (ORPS Report ALA-LA-LANL-TA55-1993-0002).
The contamination occurred during an attempt to clear the argon lines of the slag left by the reduction process performed on January 14 (ref. ORPS Report ALA-LA-LANL-TA55- 1993-0001). On January 14, 1993, personnel had performed a laser-initiated reduction of plutonium tetraflouride by calcium metal. One day earlier, they had attempted to complete a required pressure test to verify the integrity of the system. They performed four pressure cycles, and on the last test the CAM alarmed, indicating a leak. Then, on January 14, they repeated the pressure test attempting to locate the previously identified leak. All test personnel wore respirators and protective clothing because of the suspected leak. They successfully completed the test with no indications of any leakage or contamination. They then proceeded with the reduction process without respirators based upon the test results. The reduction process deposited debris (slag) throughout the reaction chamber and obstructed the argon flow lines. The facility procedure followed on January 19 for clearing the slag provides instructions to blow argon through the plugged orifices in the lines. The argon then flows into the open reaction chamber, and from there into the glove-box.
Facility personnel detected the January 19 leak in the glove-box at the laser initiation device penetration. This penetration is sealed by rubber O-rings. Facility personnel believe the O-ring seals are the source of leakage. A thorough investigation has been initiated. The reduction apparatus and confinement will be disassembled to determine the cause of the event. Facility personnel speculate that the pressure cycles may have had an adverse effect on the sealing capabilities of the O-ring seal. Numerous components and equipment use O-ring seals. Facilities may want to review the selection, purchase, storage, handling, and use of O-ring seals at their facilities. Age, temperature, pressure, the O-ring material, and chemicals exposed to, may all affect O-ring seal performance. Application, maintenance and testing of O- rings can affect to safe operation of DOE facilities. The Space Shuttle Challenger accident is probably the most famous result of an O-ring failure.