On 9/23/18, a worker reported an equipment failure while conducting radiographic operations at a refinery in Wyoming. A magnetic stand was used to support a 2.28TBq (61.8 Ci)
Ir-192 source while performing internal tank radiography. The magnetic stand disconnected from the wall of the tank during crank out, falling and striking the 7ft guide tube and preventing the source from being retracted. The workers immediately backed up, expanded the boundary, and called the
RSO [radiation safety officer]. The
RSO advised the crew to return the source to the collimator, backup, and monitor the area while he contacted management since he was out of state. The
RSO received a second call from the workers where they stated they successfully retracted the source into the exposure device after pulling the crank to relieve the kink caused by the magnetic stand.
The crew surveyed the scene, verified the source was secure in the device, and ended their shift at the refinery. The crew arrived back in Colorado at 2100 MDT on 9/23/18, and management performed an initial assessment of the guide tube and cranks at 0715 MDT on 9/24/18.
The RSO returned from vacation on 9/25/18 and inspected the guide tube, guide tube extension, cranks, and exposure device. The RSO concluded the exposure device and cranks were operational but removed the guide tube from service because it was involved in the strike incident.
The RSO reviewed the statements from the workers and contacted the State of Colorado and the NRC. The workers statements revealed that one of the workers performed a source retrieval by dropping lead shot bags on the collimator and pulling the guide tube and extension (not the crank) to relieve the kink in guide tube. As a result, one of the employee's dosimeters went off scale. Both film badges were overnighted for processing on 9/25/18.
The root cause was determined to be the equipment failure of the magnetic stand. Employees and management discussed the incident and reminded the individuals that source retrievals should be performed by the RSO or trained management as stated in Acuren Inspection Inc. procedures, and to always properly secure magnetic stands with a safe line while performing radiography at any elevation.
- * * BRETT PAYTON TO VINCE KLCO ON 9/26/18 AT 1445 EDT * * *
The licensee received the dosimetry report. Dose to the workers was 103 mRem and 76 mRem.
Notified R4DO (Alexander) and
NMSS Events Group via email.