ENS 55221
ENS Event | |
|---|---|
05:20 Mar 7, 2021 | |
| Title | Radiography Camera Source Unable to Retract |
| Event Description | The following was received via e-mail from the Rhode Island Dept. of Health, Radiation Control Agency:
A licensee, Electric Boat Corporation, reported the inability to retract a 1.62 TBq (43.8 Ci) Co-60 source (QSA Global, Inc. Model A424-14, S/N 81346G) into the radiography exposure device (QSA Global, Inc. Model Sentry 330, S/N P30106) on March 7, 2021, at Electric Boat's Quonset Point Facility. At approximately 0120 [EDT], the [source] was [extended] without any issue. At the completion of the exposure, the radiographer attempted to retract the source into the exposure device, and attempted to re-expose the source to verify that the auto-locking mechanism on the Sentry 330 exposure device had engaged. At this time, the radiographer noted that the auto-lock did not engage and that dose rates indicated by his ND-2000A survey instrument at the reel (remote control) remained at approximately 10 mrem/hr. The radiographer then attempted to expose and retract the source to engage the locking mechanism 2 additional times without success. At approximately 0156 [EDT], the RSO [(Radiation Safety Officer)] was notified of the inability to retract a Cobalt-60 source into its exposure device. The RSO was able to observe the set up with an inspection mirror from the opposite side of the large part being inspected and determined that the guide tube had become disconnected from the collimator, exposing 10-12 feet of drive cable on the deck, and the source pigtail had become stuck in the collimator. After creating and briefing retrieval and contingency plans, source retrieval evolution began at 0640 [EDT]. The RSO Delegate secured the source pigtail in the collimator with a 6 ft long remote handling tool to prevent the source from leaving the collimator prematurely while the RSO stepped out from behind the lead shield with another 6 ft long remote handling tool to move the guide tube from the deck back up to the collimator. While the RSO was straightening out the guide tube and drive cable, a radiography supervisor was slowly retracting the drive cable at the reel to remove the 10-12 ft of drive cable slack on the deck while the RSO communicated via radio. Once the drive cable slack was removed and the RSO guided the guide tube back up to the collimator and tension on the source pigtail was released, the RSO Delegate released control of the source and it was immediately retracted by the radiography supervisor into the exposure device. The source was confirmed to be secured in its device by survey, and the evolution was declared secure at 0649 [EDT]. RI Radiation Control Agency has investigated the report by Electric Boat Corporation and has determined that this does not have generic implications for the security of sources in radiography equipment at Electric Boat Corporation. The incident is considered closed by RI Radiation Control Agency.
The following update was received via email from the Rhode Island Dept. of Health, Radiation Control Agency: Event Causes: 1) The first 1-3 male threads were rough, which lead to the female connection binding up prematurely. 2) The collimator connection was at or above the eye level of the radiographers, and obstructed from being able to perform a visual inspection of the connection. 3) Neither radiographer re-inspected nor verified the connection in the middle of the shift. Corrective Actions: By the licensee: 1) 2 collimators with male threads were identified as unsat and will be repaired or dispositioned for disposal by the RSO. 2) Thread protectors were procured and installed on equipment with exposed, male-threaded connections. 3) A Job Instruction Breakdown describing the connection and verification processes was developed. Notified R1DO (Lilliendahl) and NMSS Events Notification (by email). |
| Where | |
|---|---|
| Electric Boat Corporation North Kingstown, Rhode Island (NRC Region 1) | |
| License number: | 3D-005-01 |
| Organization: | Ri Dept Of Radiological Health |
| Reporting | |
| Agreement State | |
| Time - Person (Reporting Time:+1281.65 h53.402 days <br />7.629 weeks <br />1.756 months <br />) | |
| Opened: | Alexander Hamm 13:59 Apr 29, 2021 |
| NRC Officer: | Joanna Bridge |
| Last Updated: | Jun 29, 2021 |
| 55221 - NRC Website | |
Electric Boat Corporation with Agreement State | |
WEEKMONTHYEARENS 552212021-03-07T05:20:0007 March 2021 05:20:00
[Table view]Agreement State Radiography Camera Source Unable to Retract 2021-03-07T05:20:00 | |