Although no workers were injured, several received uptakes of uranium even though respiratory protection was used. The oxygen generation incidents were isolated incidents that originated with the use of newer drums or other modifications of equipment which allowed excessive pressures. For one licensee, the incident was a result of using newer drums with airtight seals. Older drums had less efficient seals that allowed pressure to escape as it was generated. Both licensees instituted corrective actions consisting mainly of leaving the lids off the drums for a minimum of 3 hours after filling.
Corrective actions appear to have been sufficient to prevent future incidents.
Since uranium is a pyrophoric metal, especially in fines or powder form, any contaminant in contact with yellowcake powder can be hazardous. Hydrocarbons such as lubricating oils and grease are very likely to cause an unstable condition in the packed yellowcake powder. In one incident, a leaky flange on a bag filter allowed lubricating oil to leak into and mix with the yellowcake powder in a dryer tank. Once the exothermic reaction began, temperatures rose sufficiently to turn residual water to steam, covering the room with yellowcake powder. The leak was found and repaired, but the room had to be decontaminated.