05000338/FIN-2011011-06
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Finding | |
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| Title | Seismic Alarm Panel |
| Description | The team reviewed the licensees implementation of the emergency preparedness (EP) procedures used during the event. The review focused on the circumstances surrounding the events to determine if the licensees EP classification and notifications were appropriate and timely. The team interviewed members of the licensees organization and other individuals involved with EP aspects of the event. The team reviewed the event timeline, logs, statements by individuals who responded to the event, the North Anna emergency action level (EAL) matrix, event notification worksheets, and other documents related to EP classifications. b. Observations and Findings. The team concluded that emergency planning declarations were appropriate. The team identified one URI described in this section. In order to determine the appropriateness of the EP classifications, the team performed a detailed assessment of the event timeline with particular attention to those activities that are entry points for the EAL matrix. On August 23, 2011, at 1:51 p.m., the site experienced a magnitude 5.8 earthquake with an epicenter twelve miles southwest of the plant. Both reactors tripped. A LOOP occurred at 1:51:12 p.m. All four EDGs auto started to their respective emergency bus (1H, 1J, 2H, and 2J) at 1:51:20 p.m. An Alert was declared at 2:03 p.m. for HA6.1, SM judgment, due to an inability to enter the seismic EAL for seismic event because the seismic monitoring panel earthquake trouble alarm to notify operators of a seismic event did not illuminate. HA1.1, earthquake response, required that the strong motion accelerograph peak shock annunciator illuminates, which would indicate a seismic event greater than OBE (0.06g horizontal or 0.04g vertical) and an earthquake confirmed by any of the following: FnEarthquake felt in plant FnNational Earthquake Information Center (NEIC) FnControl Room indication of degraded performance of any safety-related structure, system, or component The strong motion accelerograph peak shock annunciator did not illuminate. The seismic monitoring panel has two recording systems, one provided by Kinemetrics Inc. and the other provided by Engdahl. Both systems provide input to the main control room via a common instrumentation panel on the Unit 2 side of the control room. All sensors for the Kinemetrics system are located inside Unit 1 containment. The Kinemetrics system has a seismic trigger, which activates at 0.01g in a any direction. In addition, there is a seismic switch which activates at 0.04g vertical and 0.06 horizontal. Neither the seismic switch nor the seismic trigger activated the earthquake trouble alarm. Locally at the seismic panel, the seismic trigger was activated and a tape recording of the event was recorded. Therefore, operators determined that the seismic monitoring panel was inoperable for making a decision about the strength of the earthquake. The team determined that the lack of control panel alarm from the seismic monitoring panel did not delay an Alert declaration, because the SM used HA6.1, SM judgment. Because of the issues identified with the seismic monitoring panel and because it is used as an input for EAL decisions, additional review by the NRC will be needed to determine whether this issue represents a performance deficiency. An unresolved item will be opened pending completion of this review. The issue will be identified as URI 05000338, 339/2011011-06: Seismic Alarm Panel. Personnel in the plant monitoring the 2H EDG reported the coolant leak to the control room via face-to-face communication. Operators tripped the 2H EDG at 2:40 p.m. An Alert was declared at 2:55 p.m. for SA1.1, AC power, for Unit 2, because the AC capability was reduced to a single source with 2J EDG. The team determined that notifications to the State and Counties and to the NRC Operations Center were timely and accurate. The Alert event was downgraded to a Notice of Unusual Event (NOUE) at 11:16 a.m. on August 24, for HU1.1, seismic activity, due to the potential for aftershocks. The NOUE was exited on August 24, 2011, at 1:15 p.m. The decision to terminate the event was based on the following: (1) no public issues existed that would necessitate the continued activation of the State and County Emergency Operations Facilities; (2) the licensees Outage Control Center had established a technical focus and was aligned for the recovery activities; and (3) no additional aftershocks were received at the plant. The team determined that downgrade of the Alert event at 11:16 a.m. was appropriate. |
| Site: | North Anna  |
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| Report | IR 05000338/2011011 Section 4OA5 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 93800 |
| Inspectors (proximate) | G Kolcum L Suggs M Chakravorty M Franke R Jackson S Park S Walker V Mccree Y Lie Leag Kolcum G Mccoy L Lake M Yoo R Clagg |
| INPO aspect | |
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Finding - North Anna - IR 05000338/2011011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (North Anna) @ 2011Q4
Self-Identified List (North Anna)
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