Glovebox gloves should be routinely inspected regardless of location or frequency of use.

Procedures should address actions for unanticipated conditions discovered during work or at startup.

A glovebox became pressurized and a glove ruptured at the Chemistry and Metallurgy Research (CMR) facility. The rupture resulted in widespread contamination of equipment, work surfaces, and the floor. No personnel were in the room when the glove ruptured. The figure shows the ruptured glove

A six-inch crack was found in the glass above the glove port next to the blown-off glove. The glovebox fire screens and outlet HEPA filters were inspected, and the screens were found to be almost completely clogged with solid residues.

Investigators believe that the decomposition of ammonium nitrate, a constituent in a mixed waste treatability study process being conducted in the glovebox, was catalyzed by the presence of transition metal elements in the waste. The glovebox exhaust system had been compromised by water vapor condensation in the HEPA filter and a finely divided powder plugging the fire screen. Consequently, the exhaust system could not accommodate the rapid generation of gases from the decomposition reaction. There was no evidence of an explosion.

BACKGROUND:

Personnel involved in the mixed waste treatability study had been slowly evaporating liquid from solutions in trays on hot plates in the glovebox. The solutions contained water, ammonia, nitrates, hydrogen peroxide, sulfates, potassium, fluorides, and transition metals such as copper, zinc, nickel, iron, and a radioactive isotope of technetium.

The evaporation process was continually attended during working hours except during lunch breaks, and the hot plates were turned off at the end of the day. When unattended, the glovebox gloves were tied outside the gloveboxes to keep them from touching the hot plates.

Each day study personnel observed a slow continual rise in the magnahelic gauge readings on the two gloveboxes used for the evaporation work, indicating an increase in glovebox pressure relative to the laboratory. The treatability study team leader recognized that the increased readings were the result of the HEPA filters being wetted by water vapor. The gauge readings dropped back to normal overnight, presumably as the filters dried.

The personnel also experienced problems with the glovebox HEPA filters and fire screens repeatedly clogging as a result of the high level of ammonium nitrate precipitate generated by the evaporation process. Additionally, the fire screens, which were added by study personnel, adversely impacted the ability of the magnahelic gauges to accurately measure glovebox pressure differential.

Neither the team members nor facility management adequately employed required change control procedures to assure formal reviews (i.e., USQD, design change package, and hazard review) were performed when the fire screens were installed. The change control procedures apply to any physical change to safety significant equipment to ensure that possible impacts on the facility's authorization basis and engineering controls are assessed.

Although the study team leader prepared a special work permit for the fire screen installation work, the permit did not indicate why the screens were necessary or what effect their installation would have on the glovebox magnahelic gauges. The area work supervisor assumed the work was routine and that installation of the screens would make the gloveboxes safer. The area work supervisor and the facility manager signed off on the permit without obtaining any additional information from team members.

All installed glovebox gloves should be periodically inspected for damage and/or deterioration regardless of how frequently they are used. Consideration should also be given to establishing a routine glove replacement interval in addition to storage life limitations. If established, replacement intervals should take into account waste minimization requirements.

In addition to the change control procedures that were already in place, guidance was developed on reanalyzing work when unanticipated conditions or hazards are encountered. The change control process was also revised to improve the timeliness of the process, which previously took from several months to more than a year to complete. Training for team leaders is also under development to ensure that personnel understand the roles and responsibilities team leaders are expected to fulfill.

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