05000387/FIN-2011005-06
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Finding | |
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| Title | Loss of Shield Control During Source Load |
| Description | On December 5, 2011, PPL received an 1100 curie Cs-137 sealed source and conducted a source transfer into a Hopewell Designs (HD) BX-3 HP survey instrument calibrator. During the initial attempt to lower the source from the transfer shield into the calibrator, the shield door (plug) in the bottom of the transfer shield could not be withdrawn the prescribed 2 inches in order to lower the source down into the calibrator. The HD contractor directed an effluents technician to use additional tooling in order to provide additional manual pressure to withdraw the shield plug. During this subsequent attempt, the shield plug was withdrawn about five inches (three inches further than prescribed) reducing the remaining lead shielding from the source, to about one and one-half inches. The electronic dosimeters worn by the HD contractor and the effluents technician immediately alarmed indicating unexpected high dose rates, and the health physics technicians directed the shield plug to be reinserted, which immediately occurred, returning the dose rates back to normal. It was determined that the exposure time was approximately three seconds. The work group (consisting of the HD contractor, HP supervisor, two HP technicians and the effluents technician), stopped the work activity and reviewed the radiological exposure status of the workers. It was determined that the peak does rates were of 8 R/hr and 2 R/hr; doses of 6.4 mrem (whole body) and 3.3 mrem (whole body) indicated for the effluents technicians and HD contractors electronic dosimeters, respectively. Maximum dose rates were calculated to be ~58R/hr on the surface of the shield plug where the effluent technicians hand was. The HD contractor recommended moving forward to attempt the same work activity in order to put the source into a safe configuration. The PPL HP supervisor concurred and the work group resumed the source load operation. This time the Cs-137 source was lowered into the BX-3 calibrator without further incident. Immediately after the source load operation was successfully completed, PPL management was informed and an investigation was initiated, convening a root cause analysis (RCA) team, to determine the cause and initiate appropriate corrective actions. The NRC had a number of issues related to this event including adherence to radiological work practices in conducting the evolution and proceeding after the initial event, the adequacy of the radiological monitoring used, design control and vendor knowledge concerns related to the configuration of the source transfer assembly, and whether appropriate procedures were used and followed for the evolution. Follow-up inspections for the 10 CFR Part 36 and Part 50 licensees are being conducted by DNMS and DRS/DRP respectfully. At the conclusion of this inspection period, PPL was still in the process of conducting an RCA of the source load event. Final NRC conclusions regarding performance deficiencies and enforcement actions have not yet been determined pending a review of PPLs CAP investigation results. This issue will be tracked as an unresolved item (URI) pending further inspection and review of PPLs completed RCA investigation. |
| Site: | Susquehanna  |
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| Report | IR 05000387/2011005 Section 4OA3 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | A Bolger J Greives P Finney P Krohn R Rolph T O'Haraa Rosebrookc Crisden D Schroeder E Miller J Furia J Greives J Noggle K Modes P Finney P Krohn R Fuhrmeister S Ibarrola T Fish W Schmidt |
| INPO aspect | |
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Finding - Susquehanna - IR 05000387/2011005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Susquehanna) @ 2011Q4
Self-Identified List (Susquehanna)
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