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{{#Wiki_filter:Rivera-Ortiz, Joel From: Sent: To:  
{{#Wiki_filter:Rivera-Ortiz, Joel From:                                                                       Munday, Joel ,- V4 Sent:                                                                       Monday, August 29, 2011 7:28 AM To:                                                                         Rivera-Ortiz, Joel


==Subject:==
==Subject:==
Attachments:
FW: Documents Related to North Anna NPP Earthquake Issue Attachments:                                                                North Anna Site Visit Notes.word.docx; Talking Points for North Anna NPP Seismic Event final.word.docx; FW: North Anna timeline FYI From: McCree, Victor Sent: Sunday, August 28, 2011 11:22 PM To: Wert, Leonard; Croteau, Rick; Munday, Joel Cc: Christensen, Harold; Jones, William
Munday, Joel ,- V4 Monday, August 29, 2011 7:28 AM Rivera-Ortiz, Joel FW: Documents Related to North Anna NPP Earthquake Issue North Anna Site Visit Notes.word.docx; Talking Points for North Anna NPP Seismic Event final.word.docx; FW: North Anna timeline FYI From: McCree, Victor Sent: Sunday, August 28, 2011 11:22 PM To: Wert, Leonard; Croteau, Rick; Munday, Joel Cc: Christensen, Harold; Jones, William  


==Subject:==
==Subject:==
Fw: Documents Related to North Anna NPP Earthquake Issue FYI This email is being sent from an NRC Blackberry device....... ....,:: ...................  
Fw: Documents Related to North Anna NPP Earthquake Issue FYI This email is being sent from an NRC Blackberry device.
..,, .,: .,, , .,:..,,,,,,,, ,,.,.,,,,,..,,...,...,,,:..,, ,...,.,.,...,..,.,.:,,,, ,,,.,,......
From: Khanna, Meena To: McCree, Victor Cc: Franke, Mark Sent: Sun Aug 28 22:57:54 2011
.... ... ..... ....... ...... .......,.,..:,,.....,..,.,,..,.,,.,,......
...... ...... ...... , ... ...... .......,..... ...... ...... ...... ...... ........,.......,,,,,,,,.,,:,,,.....
...... ...... ...... ...... ....... ...... ...... ...... ...... ...... ............
...... ............
...... ...... ...... ...... ......From: Khanna, Meena To: McCree, Victor Cc: Franke, Mark Sent: Sun Aug 28 22:57:54 2011  


==Subject:==
==Subject:==
Documents Related to North Anna NPP Earthquake Issue Hi Victor, attached are the documents that we will be discussing at the 7:30 am meeting, tomorrow.
Documents Related to North Anna NPP Earthquake Issue Hi Victor, attached are the documents that we will be discussing at the 7:30 am meeting, tomorrow. The third attachment is a timeline that the region provided...we just added that as an fyi...thanks!
The third attachment is a timeline that the region provided...we just added that as an fyi...thanks!
Meena Khanna, Branch Chief Mechanical and Civil Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation (301)415-2150 meena.khanna@nrc.Qov
Meena Khanna, Branch Chief Mechanical and Civil Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation (301)415-2150 meena.khanna@nrc.Qov North Anna Site Visit Notes (Week of August 22, 2011)Yong Li and George Thomas from NRR/DE conducted a site visit at North Anna during the week of August 22, 2011, to evaluate the issues related to the recent earthquake.
 
They met with the licensee and presented questions from NRR/NRO/RES to the licensee and looked at Earthquake instrument panel in the control room. A summary of the status of the visit, to date, is provided below: " The licensee conducted the 1 st walkdown of the plant with focus on safety related SSC (except the containment) within 8 hours in accordance with the North Anna Power Station abnormal procedure for seismic event. From the walkdown, the licensee identified many discrepancies for which condition reports have been written. The damages noted were generally minor.* Among the items identified through the initial walkdown, the bushing of all four transformers were found to be damaged and the oil leaked from the transformer which caused the turbine generator to trip, resulting in shutdown of the reactor. The other items were identified to be "superficial," such as, minor cracks on walls, loose insulation, conduits coming lose, 25 of 27 ISFSI vertical casks moved horizontally 0.5 inches to 3 inches, etc.* The licensee conducted the 2 nd walkdown after the aftershock triggered at 2 am on 8/25/11; however, no additional discrepancies were identified.
North Anna Site Visit Notes (Week of August 22, 2011)
In the mean time, the licensee is in the process of developing specific guidance in preparation for detailed walkdowns." The licensee indicated that all seismic monitors are contained in the Unit 1 containment at different levels of the structures as well as in the auxiliary building.
Yong Li and George Thomas from NRR/DE conducted a site visit at North Anna during the week of August 22, 2011, to evaluate the issues related to the recent earthquake. They met with the licensee and presented questions from NRR/NRO/RES to the licensee and looked at Earthquake instrument panel in the control room. A summary of the status of the visit, to date, is provided below:
No seismic monitors are located in the Unit 2 building.* Scratch plate readings from the auxiliary building basemat were sent to California to be interpreted by a vendor. We were informed that the time histories initially sent to Calvert Cliffs are being sent to California to be interpreted.
    " The licensee conducted the 1st walkdown of the plant with focus on safety related SSC (except the containment) within 8 hours in accordance with the North Anna Power Station abnormal procedure for seismic event. From the walkdown, the licensee identified many discrepancies for which condition reports have been written. The damages noted were generally minor.
Those interpretations were received by the licensee for the auxiliary building.
* Among the items identified through the initial walkdown, the bushing of all four transformers were found to be damaged and the oil leaked from the transformer which caused the turbine generator to trip, resulting in shutdown of the reactor. The other items were identified to be "superficial," such as, minor cracks on walls, loose insulation, conduits coming lose, 25 of 27 ISFSI vertical casks moved horizontally 0.5 inches to 3 inches, etc.
Scratch plates from Unit 1 containment basemat have been sent to California." Since the licensee doesn't have a seismic monitor located in the free field on the free surface, therefore, a strictly comparison of ground motion for SSE and OBE is difficult.
* The licensee conducted the 2 nd walkdown after the aftershock triggered at 2 am on 8/25/11; however, no additional discrepancies were identified. In the mean time, the licensee is in the process of developing specific guidance in preparation for detailed walkdowns.
However, the staff confirmed with the licensee that design response spectra at the mat and different levels are available and a comparison can be carried out between the original design and the recorded data when all the seismic readings from the seismometers are confirmed." On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.  
    " The licensee indicated that all seismic monitors are contained in the Unit 1 containment at different levels of the structures as well as in the auxiliary building. No seismic monitors are located in the Unit 2 building.
.Talking Points for North Anna NPP Seismic Event Desiqn Basis 0 North Anna Nuclear Power Plant (NANPP) has two Design Basis Earthquake (DBE) ground motion, one for structures, systems, and components (SSCs) founded on top of rock, which is anchored at 0.12 g, and the other is for SSCs founded on top of soil, which is anchored at 0.18 g.* NANPP has two corresponding Operating Basis Earthquake (OBE) ground motion, anchored at 0.06 g for rock and 0.09 g for soil.Seismic Event* Earthquake of August 23 occurred at a close distance (approx. 18 km) to the plant with a magnitude of 5.8 at a relatively shallow depth. Approximately 11 aftershocks have followed since then, the worst one of which was of magnitude 4.5.Seismic Impact at NANPP* Initial interpretation of data obtained from the licensee's seismic Response Spectrum Recorder (scratch plates) located in the auxiliary building (at top of basemat (EL 241 ft) and at EL 273 ft) indicate that the acceleration experienced at the NANPP Auxiliary Building has exceeded the corresponding DBE spectrum in at frequencies above 8 Hz, by a factor of approximately 1.5 to 2, in the vertical and horizontal directions.
* Scratch plate readings from the auxiliary building basemat were sent to California to be interpreted by a vendor. We were informed that the time histories initially sent to Calvert Cliffs are being sent to California to be interpreted. Those interpretations were received by the licensee for the auxiliary building. Scratch plates from Unit 1 containment basemat have been sent to California.
    " Since the licensee doesn't have a seismic monitor located in the free field on the free surface, therefore, a strictly comparison of ground motion for SSE and OBE is difficult.
However, the staff confirmed with the licensee that design response spectra at the mat and different levels are available and a comparison can be carried out between the original design and the recorded data when all the seismic readings from the seismometers are confirmed.
    " On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.
 
                            . Talking Points for North Anna NPP Seismic Event Desiqn Basis 0 North Anna Nuclear Power Plant (NANPP) has two Design Basis Earthquake (DBE) ground motion, one for structures, systems, and components (SSCs) founded on top of rock, which is anchored at 0.12 g, and the other is for SSCs founded on top of soil, which is anchored at 0.18 g.
* NANPP has two corresponding Operating Basis Earthquake (OBE) ground motion, anchored at 0.06 g for rock and 0.09 g for soil.
Seismic Event
* Earthquake of August 23 occurred at a close distance (approx. 18 km) to the plant with a magnitude of 5.8 at a relatively shallow depth. Approximately 11 aftershocks have followed since then, the worst one of which was of magnitude 4.5.
Seismic Impact at NANPP
* Initial interpretation of data obtained from the licensee's seismic Response Spectrum Recorder (scratch plates) located in the auxiliary building (at top of basemat (EL 241 ft) and at EL 273 ft) indicate that the acceleration experienced at the NANPP Auxiliary Building has exceeded the corresponding DBE spectrum in at frequencies above 8 Hz, by a factor of approximately 1.5 to 2, in the vertical and horizontal directions.
* The USGS estimates, as of August 26, indicate the peak ground acceleration (PGA) at the North Anna site between 0.20g and 0.27g .The response spectrum corresponding to these estimated PGA values exceed the NANPP DBE spectrum over some frequency range. Data from the seismic response spectrum recorders in the Unit 1 containment are currently being interpreted.
* The USGS estimates, as of August 26, indicate the peak ground acceleration (PGA) at the North Anna site between 0.20g and 0.27g .The response spectrum corresponding to these estimated PGA values exceed the NANPP DBE spectrum over some frequency range. Data from the seismic response spectrum recorders in the Unit 1 containment are currently being interpreted.
* 25 of 27 vertical casks at the ISFSI have displaced horizontally 0.5 to 3 inches.* After the initial walkdown, the licensee generated a Condition Report to describe all the discrepancies identified.
* 25 of 27 vertical casks at the ISFSI have displaced horizontally 0.5 to 3 inches.
* On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.NRC Evaluations" NRC staff performed an independent analysis using the best estimate of the earthquake location and magnitude together with the EPRI ground motion prediction equations.
* After the initial walkdown, the licensee generated a Condition Report to describe all the discrepancies identified.
The staffs calculation is lower than USGS' estimate on the ground motion at the site (see attached Figure).* The staff will confirm that the licensee is performing plant walk downs in accordance with RG 1.166,"Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions," which endorses sections of EPRI NP-6695, "Guidelines for Nuclear Plant Response to an Earthquake," with certain exceptions.
* On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.
RG 1.166 also refers to RG 1.167." Information from NANPP's seismic recordings will provide the basis for the staffs assessment of the licensee's operability determination of the affected structures and components.
NRC Evaluations
o The staff will confirm that the licensee is following the guidance in RG 1.167, "Restart of a Nuclear Power Plant Shutdown by a Seismic Event," regarding the exceptions to the EPRI NP-6695 document prior to recommending plant restart.Significant Information Outstanding for Assessing Seismic Motions and Effects* Results from seismic response spectrum recorders (scratch plates) and other seismic instrumentation in Unit 1 containment.
    " NRC staff performed an independent analysis using the best estimate of the earthquake location and magnitude together with the EPRI ground motion prediction equations. The staffs calculation is lower than USGS' estimate on the ground motion at the site (see attached Figure).
* Validation of onsite instrumentation and outputs* ISFSI response* Results of initial walkdowns inside containment Actions for Seismic Spectrum Beyond Design Basis* Appendix S to Part 100-Paragraph V(a)(2), "Determination of Operating Basis Earthquake" (this regulation does not address beyond design basis events.)* RG 1.166, "Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions"* RG 1.167, "Restart Of A Nuclear Power Plant Shut Down By A Seismic Event" Licensee Actions" As of August 26, the licensee was in the process of coming down to a safe shutdown condition." The licensee will begin making the 50.72 reports (at least one 1 hr call) that are required now that this determination has been made and ensuring compliance with the applicable TS action statements." Licensee is currently in the process of developing plans and procedures for detailed walkdowns and other evaluations and actions to be taken prior to restart.NRC Actions* Region II with NRR/NRO support will be conducting an AIT at the North Anna site, in accordance with MD 8.3, "NRC Incident Investigation Program." The AIT will be led by Mark Franke. The entrance meeting is scheduled for August 30. The AIT is being chartered to collect data and determine the facts and circumstances related to the North Anna Nuclear Power Plant seismic event associated with the August 23 earthquake.
* The staff will confirm that the licensee is performing plant walk downs in accordance with RG 1.166, "Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions,"
Upon completion of the inspection, the NRC will issue an inspection report.Plant Restart* Appendix S to Part 100-Paragraph V(a)(2) states, "If vibratory ground motion exceeding that of the Operating Basis Earthquake occurs, shutdown of the nuclear power plant will be required.
which endorses sections of EPRI NP-6695, "Guidelines for Nuclear Plant Response to an Earthquake,"
Prior to resuming operations, the licensee will be required to demonstrate to the Commission that no functional damage occurred to those features necessary for continued operation without undue risk to the health and safety of the public."* NRR agrees with OGC that the NRR Director would be the authorized official to approve plant restart.Potentially Affected Plants The list below provides the plants and the associated distance from the Epicenter:
with certain exceptions. RG 1.166 also refers to RG 1.167.
North Anna is 18 km from the Epicenter Surry is 139 km from the Epicenter Calvert Cliffs is 141 km from the Epicenter DE will work with DORL Project Managers to confirm that the OBE was not exceeded at Surry and Calvert Cliffs.Relation to GI-199 The potential for the occurrence of an earthquake larger than the recent event is within the scope of GI-199 Generic Letter (GL), where licensees are requested to perform seismic risk evaluation based on latest seismic hazard estimates.
    " Information from NANPP's seismic recordings will provide the basis for the staffs assessment of the licensee's operability determination of the affected structures and components.
The GL provides a systematic process to perform the requested evaluations and determine the delta increase in seismic core damage frequency.
o The staff will confirm that the licensee is following the guidance in RG 1.167, "Restart of a Nuclear Power Plant Shutdown by a Seismic Event," regarding the exceptions to the EPRI NP-6695 document prior to recommending plant restart.
2.0 0 ci)Ciz 0z C,)NA Unit 1 &2 Rock SSE (Newmark at 0. 12g)--OBE (1/2 SSE)--- NA Unit 3 COL GMRS ,:. USGS (ShakeCast Report Version 6)1.5 1.0-0.5-EPRI GMPE(2004.
Significant Information Outstanding for Assessing Seismic Motions and Effects
2006)*
* Results from seismic response spectrum recorders (scratch plates) and other seismic instrumentation in Unit 1 containment.
* median and +/- I sd Mw5. 8 att 26kin //1////IN 2.0.0 C-1---- , 0.1 1 10 frequency (Hz)100 Rivera-Ortiz, Joel From: Sent: To:  
* Validation of onsite instrumentation and outputs
* ISFSI response
* Results of initial walkdowns inside containment
 
Actions for Seismic Spectrum Beyond Design Basis
* Appendix S to Part 100-Paragraph V(a)(2), "Determination of Operating Basis Earthquake" (this regulation does not address beyond design basis events.)
* RG 1.166, "Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions"
* RG 1.167, "Restart Of A Nuclear Power Plant Shut Down By A Seismic Event" Licensee Actions
  " As of August 26, the licensee was in the process of coming down to a safe shutdown condition.
  " The licensee will begin making the 50.72 reports (at least one 1 hr call) that are required now that this determination has been made and ensuring compliance with the applicable TS action statements.
  " Licensee is currently in the process of developing plans and procedures for detailed walkdowns and other evaluations and actions to be taken prior to restart.
NRC Actions
* Region II with NRR/NRO support will be conducting an AIT at the North Anna site, in accordance with MD 8.3, "NRC Incident Investigation Program." The AIT will be led by Mark Franke. The entrance meeting is scheduled for August 30. The AIT is being chartered to collect data and determine the facts and circumstances related to the North Anna Nuclear Power Plant seismic event associated with the August 23 earthquake. Upon completion of the inspection, the NRC will issue an inspection report.
Plant Restart
* Appendix S to Part 100-Paragraph V(a)(2) states, "If vibratory ground motion exceeding that of the Operating Basis Earthquake occurs, shutdown of the nuclearpower plant will be required. Priorto resuming operations,the licensee will be requiredto demonstrate to the Commission that no functional damage occurredto those features necessary for continued operation without undue risk to the health and safety of the public."
* NRR agrees with OGC that the NRR Director would be the authorized official to approve plant restart.
Potentially Affected Plants The list below provides the plants and the associated distance from the Epicenter:
North Anna is 18 km from the Epicenter Surry is 139 km from the Epicenter Calvert Cliffs is 141 km from the Epicenter DE will work with DORL Project Managers to confirm that the OBE was not exceeded at Surry and Calvert Cliffs.
Relation to GI-199 The potential for the occurrence of an earthquake larger than the recent event is within the scope of GI-199 Generic Letter (GL), where licensees are requested to perform seismic risk evaluation based on latest seismic hazard estimates. The GL provides a systematic process to perform the requested evaluations and determine the delta increase in seismic core damage frequency.
 
2.0 NA Unit 1&2 Rock SSE (Newmark at 0. 12g)
            -   -   OBE (1/2 SSE)
            ---     NA Unit 3 COL GMRS 1.5
                ,:. USGS (ShakeCast Report Version 6) 0 EPRI GMPE(2004. 2006) Mw5. 8 att 26kin /
ci)           *
* median and +/- I sd 1
                                                              /
IN 1.0-Ciz                                                        /
0z                                                        /
                                                        /
                                                      /
0.5-C,)
2.
0.0 C-1---- ,
0.1                           1               10               100 frequency (Hz)
 
Rivera-Ortiz, Joel From:                               Li, Yong Sent:                             Sunday, August 28, 2011 3:23 PM To:                                 Khanna, Meena; kamal.manoloy@nrc.gov


==Subject:==
==Subject:==
Attachments:
FW: North Anna timeline Attachments:                        North Anna Timeline revision 1.docx From: Kolcum, Gregory Sent: Friday, August 26, 2011 10:48 AM To: Li, Yong; Thomas, George
Li, Yong Sunday, August 28, 2011 3:23 PM Khanna, Meena; kamal.manoloy@nrc.gov FW: North Anna timeline North Anna Timeline revision 1.docx From: Kolcum, Gregory Sent: Friday, August 26, 2011 10:48 AM To: Li, Yong; Thomas, George  


==Subject:==
==Subject:==
North Anna timeline Gregory Kolcum Senior Resident Inspector Region II, Division of Reactor Projects U. S. Nuclear Regulatory Commission North Anna Power Station Office: 540-894-5421 P. 0. Box 490 Fax: 540-894-5650 Mineral VA 23117 1 North Anna Timeline: 8/23/2011, Tuesday 1348 Earthquake felt (5.8 USGS.gov)1349 Loop, all EDGs started and loaded 1351 Unit 1 negative rate trip, turbine trip on Main transformer relay due to earthquake 1351 Unit 2 negative rate trip, manual trip of turbine, had to manually close some main steam trip valves 1403 Alert HA6.1 1432 TSC activated 1440 Secured 2H EDG due to coolant leak. SAI.1 declared after 2H EDG secured.1520 AP-36 entered due to seismic trigger activated 1533 SBO DG started and 2H emergency bus energized 1740 Transferred 2J E bus to C RSST 1745 Secured 2J EDG 1748 Energized 1H from F transfer bus, securing 1H EDG 2003 B RSST energized 2004 Aftershock felt in MCR (4.2 USGS.gov)2017 A RSST Energized 2051 1J E bus energized from A RSST, secured 1J EDG 2117 2H EDG available 8/24/2011, Wednesday 0851 Ul started cooldown 1116 Exit Alert to NOUE HU1.1 (seismic)1315 NOUE exited 1328 U 1 entered Mode 4 2126 Ul entered Mode 5 8/25/2011, Thursday 0108 earthquake aftershock felt in MCR (4.5 USGS.gov)0118 NOUEHU1.1 1137 U2 started cooldown 1622 U2 entered Mode 4 1704 2H EDG Available}}
North Anna timeline Gregory Kolcum Senior Resident Inspector Region II, Division of Reactor Projects U.S. NuclearRegulatory Commission North Anna Power Station       Office: 540-894-5421 P. 0. Box 490                     Fax: 540-894-5650 Mineral VA 23117 1
 
North Anna Timeline:
8/23/2011, Tuesday 1348 Earthquake felt (5.8 USGS.gov) 1349 Loop, all EDGs started and loaded 1351 Unit 1 negative rate trip, turbine trip on Main transformer relay due to earthquake 1351 Unit 2 negative rate trip, manual trip of turbine, had to manually close some main steam trip valves 1403 Alert HA6.1 1432 TSC activated 1440 Secured 2H EDG due to coolant leak. SAI.1 declared after 2H EDG secured.
1520 AP-36 entered due to seismic trigger activated 1533 SBO DG started and 2H emergency bus energized 1740 Transferred 2J E bus to C RSST 1745 Secured 2J EDG 1748 Energized 1H from F transfer bus, securing 1H EDG 2003 B RSST energized 2004 Aftershock felt in MCR (4.2 USGS.gov) 2017 A RSST Energized 2051 1J E bus energized from A RSST, secured 1J EDG 2117 2H EDG available 8/24/2011, Wednesday 0851 Ul started cooldown 1116 Exit Alert to NOUE HU1.1 (seismic) 1315 NOUE exited 1328 U1 entered Mode 4 2126 Ul entered Mode 5 8/25/2011, Thursday 0108 earthquake aftershock felt in MCR (4.5 USGS.gov) 0118 NOUEHU1.1 1137 U2 started cooldown 1622 U2 entered Mode 4 1704 2H EDG Available}}

Latest revision as of 19:08, 6 February 2020

E-mail from J. Munday, Region II to J. Rivera-Ortiz, Region II; FW: Documents Related to North Anna NPP Earthquake Issue
ML12005A026
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 08/29/2011
From: Joel Munday
NRC/RGN-II
To: Rivera-Ortiz J
NRC/RGN-II
References
FOIA/PA-2011-0357
Download: ML12005A026 (7)
v • d • e


Text

Rivera-Ortiz, Joel From: Munday, Joel ,- V4 Sent: Monday, August 29, 2011 7:28 AM To: Rivera-Ortiz, Joel

Subject:

FW: Documents Related to North Anna NPP Earthquake Issue Attachments: North Anna Site Visit Notes.word.docx; Talking Points for North Anna NPP Seismic Event final.word.docx; FW: North Anna timeline FYI From: McCree, Victor Sent: Sunday, August 28, 2011 11:22 PM To: Wert, Leonard; Croteau, Rick; Munday, Joel Cc: Christensen, Harold; Jones, William

Subject:

Fw: Documents Related to North Anna NPP Earthquake Issue FYI This email is being sent from an NRC Blackberry device.

From: Khanna, Meena To: McCree, Victor Cc: Franke, Mark Sent: Sun Aug 28 22:57:54 2011

Subject:

Documents Related to North Anna NPP Earthquake Issue Hi Victor, attached are the documents that we will be discussing at the 7:30 am meeting, tomorrow. The third attachment is a timeline that the region provided...we just added that as an fyi...thanks!

Meena Khanna, Branch Chief Mechanical and Civil Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation (301)415-2150 meena.khanna@nrc.Qov

North Anna Site Visit Notes (Week of August 22, 2011)

Yong Li and George Thomas from NRR/DE conducted a site visit at North Anna during the week of August 22, 2011, to evaluate the issues related to the recent earthquake. They met with the licensee and presented questions from NRR/NRO/RES to the licensee and looked at Earthquake instrument panel in the control room. A summary of the status of the visit, to date, is provided below:

" The licensee conducted the 1st walkdown of the plant with focus on safety related SSC (except the containment) within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in accordance with the North Anna Power Station abnormal procedure for seismic event. From the walkdown, the licensee identified many discrepancies for which condition reports have been written. The damages noted were generally minor.

  • Among the items identified through the initial walkdown, the bushing of all four transformers were found to be damaged and the oil leaked from the transformer which caused the turbine generator to trip, resulting in shutdown of the reactor. The other items were identified to be "superficial," such as, minor cracks on walls, loose insulation, conduits coming lose, 25 of 27 ISFSI vertical casks moved horizontally 0.5 inches to 3 inches, etc.
  • The licensee conducted the 2 nd walkdown after the aftershock triggered at 2 am on 8/25/11; however, no additional discrepancies were identified. In the mean time, the licensee is in the process of developing specific guidance in preparation for detailed walkdowns.

" The licensee indicated that all seismic monitors are contained in the Unit 1 containment at different levels of the structures as well as in the auxiliary building. No seismic monitors are located in the Unit 2 building.

  • Scratch plate readings from the auxiliary building basemat were sent to California to be interpreted by a vendor. We were informed that the time histories initially sent to Calvert Cliffs are being sent to California to be interpreted. Those interpretations were received by the licensee for the auxiliary building. Scratch plates from Unit 1 containment basemat have been sent to California.

" Since the licensee doesn't have a seismic monitor located in the free field on the free surface, therefore, a strictly comparison of ground motion for SSE and OBE is difficult.

However, the staff confirmed with the licensee that design response spectra at the mat and different levels are available and a comparison can be carried out between the original design and the recorded data when all the seismic readings from the seismometers are confirmed.

" On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.

. Talking Points for North Anna NPP Seismic Event Desiqn Basis 0 North Anna Nuclear Power Plant (NANPP) has two Design Basis Earthquake (DBE) ground motion, one for structures, systems, and components (SSCs) founded on top of rock, which is anchored at 0.12 g, and the other is for SSCs founded on top of soil, which is anchored at 0.18 g.

Seismic Event

  • Earthquake of August 23 occurred at a close distance (approx. 18 km) to the plant with a magnitude of 5.8 at a relatively shallow depth. Approximately 11 aftershocks have followed since then, the worst one of which was of magnitude 4.5.

Seismic Impact at NANPP

  • Initial interpretation of data obtained from the licensee's seismic Response Spectrum Recorder (scratch plates) located in the auxiliary building (at top of basemat (EL 241 ft) and at EL 273 ft) indicate that the acceleration experienced at the NANPP Auxiliary Building has exceeded the corresponding DBE spectrum in at frequencies above 8 Hz, by a factor of approximately 1.5 to 2, in the vertical and horizontal directions.
  • The USGS estimates, as of August 26, indicate the peak ground acceleration (PGA) at the North Anna site between 0.20g and 0.27g .The response spectrum corresponding to these estimated PGA values exceed the NANPP DBE spectrum over some frequency range. Data from the seismic response spectrum recorders in the Unit 1 containment are currently being interpreted.
  • 25 of 27 vertical casks at the ISFSI have displaced horizontally 0.5 to 3 inches.
  • After the initial walkdown, the licensee generated a Condition Report to describe all the discrepancies identified.
  • On August 26, the licensee declared all safety-related SSCs of Units 1 and 2 inoperable, based on growing pieces of evidence that the DBE may have been exceeded at the site.

NRC Evaluations

" NRC staff performed an independent analysis using the best estimate of the earthquake location and magnitude together with the EPRI ground motion prediction equations. The staffs calculation is lower than USGS' estimate on the ground motion at the site (see attached Figure).

  • The staff will confirm that the licensee is performing plant walk downs in accordance with RG 1.166, "Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions,"

which endorses sections of EPRI NP-6695, "Guidelines for Nuclear Plant Response to an Earthquake,"

with certain exceptions. RG 1.166 also refers to RG 1.167.

" Information from NANPP's seismic recordings will provide the basis for the staffs assessment of the licensee's operability determination of the affected structures and components.

o The staff will confirm that the licensee is following the guidance in RG 1.167, "Restart of a Nuclear Power Plant Shutdown by a Seismic Event," regarding the exceptions to the EPRI NP-6695 document prior to recommending plant restart.

Significant Information Outstanding for Assessing Seismic Motions and Effects

  • Results from seismic response spectrum recorders (scratch plates) and other seismic instrumentation in Unit 1 containment.
  • Validation of onsite instrumentation and outputs
  • Results of initial walkdowns inside containment

Actions for Seismic Spectrum Beyond Design Basis

  • Appendix S to Part 100-Paragraph V(a)(2), "Determination of Operating Basis Earthquake" (this regulation does not address beyond design basis events.)
  • RG 1.166, "Pre-earthquake Planning and Immediate Nuclear Power Plant Operator Post-earthquake Actions"
  • RG 1.167, "Restart Of A Nuclear Power Plant Shut Down By A Seismic Event" Licensee Actions

" As of August 26, the licensee was in the process of coming down to a safe shutdown condition.

" The licensee will begin making the 50.72 reports (at least one 1 hr call) that are required now that this determination has been made and ensuring compliance with the applicable TS action statements.

" Licensee is currently in the process of developing plans and procedures for detailed walkdowns and other evaluations and actions to be taken prior to restart.

NRC Actions

  • Region II with NRR/NRO support will be conducting an AIT at the North Anna site, in accordance with MD 8.3, "NRC Incident Investigation Program." The AIT will be led by Mark Franke. The entrance meeting is scheduled for August 30. The AIT is being chartered to collect data and determine the facts and circumstances related to the North Anna Nuclear Power Plant seismic event associated with the August 23 earthquake. Upon completion of the inspection, the NRC will issue an inspection report.

Plant Restart

  • Appendix S to Part 100-Paragraph V(a)(2) states, "If vibratory ground motion exceeding that of the Operating Basis Earthquake occurs, shutdown of the nuclearpower plant will be required. Priorto resuming operations,the licensee will be requiredto demonstrate to the Commission that no functional damage occurredto those features necessary for continued operation without undue risk to the health and safety of the public."
  • NRR agrees with OGC that the NRR Director would be the authorized official to approve plant restart.

Potentially Affected Plants The list below provides the plants and the associated distance from the Epicenter:

North Anna is 18 km from the Epicenter Surry is 139 km from the Epicenter Calvert Cliffs is 141 km from the Epicenter DE will work with DORL Project Managers to confirm that the OBE was not exceeded at Surry and Calvert Cliffs.

Relation to GI-199 The potential for the occurrence of an earthquake larger than the recent event is within the scope of GI-199 Generic Letter (GL), where licensees are requested to perform seismic risk evaluation based on latest seismic hazard estimates. The GL provides a systematic process to perform the requested evaluations and determine the delta increase in seismic core damage frequency.

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Rivera-Ortiz, Joel From: Li, Yong Sent: Sunday, August 28, 2011 3:23 PM To: Khanna, Meena; kamal.manoloy@nrc.gov

Subject:

FW: North Anna timeline Attachments: North Anna Timeline revision 1.docx From: Kolcum, Gregory Sent: Friday, August 26, 2011 10:48 AM To: Li, Yong; Thomas, George

Subject:

North Anna timeline Gregory Kolcum Senior Resident Inspector Region II, Division of Reactor Projects U.S. NuclearRegulatory Commission North Anna Power Station Office: 540-894-5421 P. 0. Box 490 Fax: 540-894-5650 Mineral VA 23117 1

North Anna Timeline:

8/23/2011, Tuesday 1348 Earthquake felt (5.8 USGS.gov) 1349 Loop, all EDGs started and loaded 1351 Unit 1 negative rate trip, turbine trip on Main transformer relay due to earthquake 1351 Unit 2 negative rate trip, manual trip of turbine, had to manually close some main steam trip valves 1403 Alert HA6.1 1432 TSC activated 1440 Secured 2H EDG due to coolant leak. SAI.1 declared after 2H EDG secured.

1520 AP-36 entered due to seismic trigger activated 1533 SBO DG started and 2H emergency bus energized 1740 Transferred 2J E bus to C RSST 1745 Secured 2J EDG 1748 Energized 1H from F transfer bus, securing 1H EDG 2003 B RSST energized 2004 Aftershock felt in MCR (4.2 USGS.gov) 2017 A RSST Energized 2051 1J E bus energized from A RSST, secured 1J EDG 2117 2H EDG available 8/24/2011, Wednesday 0851 Ul started cooldown 1116 Exit Alert to NOUE HU1.1 (seismic) 1315 NOUE exited 1328 U1 entered Mode 4 2126 Ul entered Mode 5 8/25/2011, Thursday 0108 earthquake aftershock felt in MCR (4.5 USGS.gov) 0118 NOUEHU1.1 1137 U2 started cooldown 1622 U2 entered Mode 4 1704 2H EDG Available

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