05000528/FIN-2010002-04
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Finding | |
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| Title | Discrepancy with Unplanned Scrams with Complications Performance Indicator |
| Description | The inspectors identified an unresolved item (URI) associated with the licensees evaluation for an NRC Performance Indicator. Specifically, for the December 3, 2009, Unit 3 reactor trip, the licensee did not submit data for the Unplanned Scrams with Complication Performance Indicator in accordance with NEI 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 6. This discrepancy is a result of a difference in the interpretation of NEI 99-02 guidance, and shall be addressed by the Frequently Asked Questions process as defined by Inspection Procedure 71151, Performance Indicator Verification. On December 3, 2009, Unit 3 was operating at essentially full power. At3:39 a.m., a high pressure alarm was received for reactor coolant pump control bleed-off and the operators recognized that the control bleed-off isolation to the volume control tank valve CHAUV-506 was in the intermediate position and subsequently closed approximately one minute later. The crew determined that the control bleed-off would be redirected to the reactor drain tank through the system relief valve. At 3:54 a.m., a reactor drain tank high pressure alarm was received. During an attempt to pump down the reactor drain tank the crew discovered that valve CHAUV-560, the reactor drain tank isolation inside containment, was closed and would not reopen. At approximately4:05 a.m., the crew identified valve UV002, instrument air to containment isolation valve, had lost indication. Operators diagnosed a loss of instrument air to the containment and entered procedure 40AO-9ZZ06, Loss of Instrument Air. The operators manually tripped the reactor at 4:31 a.m. and entered emergency operating procedure 40EP-9EO01, Standard Post Trip Actions. At 4:32 a.m., operations personnel secured all four reactor coolant pumps to terminate the addition of reactor coolant from the reactor coolant pump controlled bleed-off to the reactor drain tank to prevent the rupture of the reactor drain tank blow out disk. At 4:41 a.m., operations personnel entered emergency operating procedure 40EP-9EO07, Loss of Offsite Power/Loss of Forced Circulation, due to the loss of forced circulation when the operators turned off the reactor coolant pumps, and due to the inability to complete the standard post trip action acceptance criteria in emergency operating procedure 40EP-9EO01.The guidance in NEI 99-02 provides criteria for determining if a scram was complicated. Specifically, it states Was the scram response procedure unable to be completed without entering another emergency operating procedure? The scram must be completed without transitioning to an additional emergency operating procedure after entering the scram response procedure (e.g. ES01 for Westinghouse). This step is used to determine if the scram was uncomplicated by counting if additional procedures beyond the normal scram response required entry after the scram. The inspectors review determined the licensee was unable to complete the scram response procedure, emergency operating procedure 40EP-9EO01, without transitioning to another emergency operations procedure, emergency operating procedure 40EP-9EO07.The licensee determined the scram was uncomplicated based on Palo Verde adopting a Westinghouse emergency operating procedure scheme. The licensee stated that for this sequence of events in a Westinghouse emergency operating procedure scheme, it would not count toward the Unplanned Scrams with Complications performance indicator. The inspectors reviewed this data and determined that based on the NEI 99-02guidance, the licensee should count this event as an Unplanned Scram with Complications until the licensee either changes their emergency operating procedure scheme to match Westinghouse, or NEI 99-02 guidance changes to allow a plant specific exemption. This URI is being opened because of a difference in the interpretation of NEI 99-02 guidance for Unplanned Scrams with Complications at Palo Verde Nuclear Generating Station: URI 05000530/2010002-04, Discrepancy with Unplanned Scrams with Complications Performance Indicator |
| Site: | Palo Verde  |
|---|---|
| Report | IR 05000528/2010002 Section 4OA1 |
| Date counted | Mar 31, 2010 (2010Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71151 |
| Inspectors (proximate) | M Catts M Baquera G Guerra R Lantz R Treadway L Carson J Bashorel Ricketsonr Lantz R Treadway L Carson J Bashore S Makor M Catts M Baquera I Anchondo |
| INPO aspect | |
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Finding - Palo Verde - IR 05000528/2010002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Palo Verde) @ 2010Q1
Self-Identified List (Palo Verde)
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