Depleted UF6 Cylinder Leakage
A small number of cylinders have leaked over the last 40 years; leaking cylinders are repaired, and material that leaks onto the ground is removed.
Chemical Reactions During Leakage
If a cylinder leak (breach) occurs and the depleted UF6 is exposed to water vapor in the air, uranyl fluoride (UO2F2) and hydrogen fluoride (HF) are formed. The uranyl fluoride is a solid that plugs the leak, limiting further escape of depleted UF6. Release of the hydrogen fluoride gas to the atmosphere is also slowed by the plug formation.
Breach (leak) in a depleted UF6 cylinder.
Historical Information about Leaks
Ten depleted UF6 cylinders have been breached (mainly from cylinder wall cracks) over the past 40 years: most of the breaches were due to corrosion around dents caused by mishandling, with the others due to corrosion around welding defects or from external corrosion alone. After the breaches were discovered, the material that leaked onto the ground was removed, and the cylinders were repaired or the UF6 was transferred to new cylinders. The cylinder yard workers and the environment around the cylinder yards are constantly monitored for potential radiation and chemical exposures and appropriate actions are taken if higher-than-expected readings are obtained from monitoring equipment.
Leak Repair Procedures
When a valve leak is detected, the valve is replaced. When cylinder wall corrosion or leakage is detected, the cylinder is repaired with a patch, followed by a welded steel repair.
Depleted UF6 Cylinder with a Patch