Double-Shell Tank AZ-101 at Hanford tested 3 times the contamination limit

Double-Shell Tank AZ-101 at Hanford tested 3 times the contamination limit


Last night, as Hanford tank farms contractor Washington River Protection Solutions was pulling a robotic device, known as a crawler, out of the annulus of Double-Shell Tank AZ-101, ongoing radiological monitoring showed contamination on the unit that was three times the planned limit. Workers immediately stopped working and exited the area according to procedure. Using established personal monitoring procedures, contamination was discovered on a worker’s clothing. Established decontamination procedures were followed, which involves removing the contaminated clothing; further surveying the worker showed no contamination remained. No other workers were affected, and all members of the crew were cleared for normal duty.

In line with existing integrated safety management protocols, WRPS developed a response plan to address the event and completed cleanup in the area this morning.

The continuous air monitor (CAM) within the tank annulus issued an alarm, but leak-detection instruments located within the annulus have not detected any liquid on the floor of the annulus space. Crews are putting together a work plan to conduct a visual video inspection of the annulus, and that will be completed within the week.

These crawler operations are being conducted as part of ultrasonic inspections which measure tank wall thickness, as part of the ongoing Double-Shell Tank (DST) integrity program.