05000269/FIN-2011003-02
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Finding | |
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| Title | Follow-up of NOED 11-2-03 |
| Description | An unresolved item (URI) was identified for NOED 11-2-03. On January 8, 2011, during Unit 1 ES digital channel 2 testing, valve 1HP-5 failed to fully close following an inadvertent close signal. A root cause investigation found that improper material selection for the gland ring in a 2003/2004 modification resulted in a loss of margin for the actuator for the valve, as well as similar valves on ONS Unit 2 and Unit 3. On May 31, 2011, discussions with valve vendor identified that the software used in the licensees operability determination for the Unit 2 and Unit 3 valves may calculate non-conservative torque values resulting in a reduction in the valves closing margin. Ongoing evaluations indicated the required spring closing forces were inadequate resulting in a negative closing margin at normal reactor coolant system pressures. On June 2, at approximately 12:10 p.m., containment isolation valves 2HP-5, 2HP-21, 3HP-5, and 3HP-21 were declared inoperable. The licensee determined that placing Unit 2 or Unit 3 in MODE 5 would result in power delivery challenges during a period of significant grid demand and could result in adverse consequences to the health and safety of the public. On this basis the licensee requested a severe weather NOED, on June 2, 2011, for a period of 14 days or until electrical grid conditions are predicted to return to normal for a period of at least 10 days to ensure the safe and orderly shutdown of one or both ONS units to restore compliance with TS 3.6.3. An independent assessment by NRC staff with consultation with SERC Reliability Corporation confirmed the licensees assertion of the grid stability conditions. The NRC verbally granted the NOED at 6:30 p.m., on June 2. The licensee returned 2HP-5, 2HP-21, 3HP-5, and 3HP-21 to operable status after performing a modification to add additional closing force to regain necessary margin on June 11, 2011. Additional inspection is required to conduct a review of the LER, root cause, and planned corrective actions. This is identified as URI 05000270, 287/2011003-02, Follow-up of NOED 11-2- 03 |
| Site: | Oconee  |
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| Report | IR 05000269/2011003 Section 4OA3 |
| Date counted | Jun 30, 2011 (2011Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | A Sabisch G Ottenberg J Bartley J Hamman K Ellis R Russella Sabischa Vargas B Collins C Rapp G Ottenberg J Bartley J Hamman K Ellis R Carriona Sabischg Ottenberg B Collins K Ellis E Stamm A Sengupta S Darbali J Bartley W Loo |
| INPO aspect | |
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Finding - Oconee - IR 05000269/2011003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Oconee) @ 2011Q2
Self-Identified List (Oconee)
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