ML11285A359

Request for Information Regarding the Earthquake of August 23, 2011

ML11285A359
Person / Time
Site:	North Anna
Issue date:	10/13/2011
From:	Meena Khanna Division of Operating Reactor Licensing
To:	Heacock D Virginia Electric & Power Co (VEPCO)
Martin R
References
TAC ME7254, TAC ME7255
Download: ML11285A359 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 October 13, 2011 Mr. David A. Heacock President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR INFORMATION REGARDING THE EARTHQUAKE OF AUGUST 23, 2011 (TAC NOS. ME7254 AND ME7255)

Dear Mr. Heacock:

The Nuclear Regulatory Commission staff is continuing its review of information submitted by the Virginia Electric and Power Company regarding activities conducted in response to the earthquake that occurred near the North Anna Power Station, Unit Nos. 1 and 2 (NAPS) on August 23, 2011.

This letter forwards requests for information on licensing, mechanical and civil engineering, piping, snubbers, and pumps and valves. Your expeditious response is requested to enable the staff to continue its review of your proposed plans for restarting the NAPS.

Sincerely, Meena Khanna Lead of North Anna Restart Team Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339

Enclosure:

Request for Information cc w/encl: Distribution via Listserv

REQUEST FOR INFORMATION VIRGINIA ELECTRIC AND POWER COMPANY (VEPCO)

NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-338 AND 50-339 The following requests for information are related to the earthquake of August 23, 2011, that occurred in the vicinity of the North Anna Power Station, Unit Nos. 1 and 2 (NAPS). Previous requests for information were issued on September 14, September 26, September 28, September 30 and October 6, 2011.

Licensing Questions:

1. Summarize the plans during mode changes and power ascensions (e.g., any planned walk downs, inspections, tests or evaluations) for NAPS. Also, provide the schedule for submitting the NAPS Restart Plan.

2. By letter dated September 17,2011, the licensee stated that its readiness assessment was based, in part, on the guidance of Regulatory Guide (RG) 1.167, "Restart of a Nuclear Plant Shut down by a Seismic Event."

(a) RG 1.167, Section C.2, states that "coincident with the long term evaluations, the plant should be restored to its current licensing basis." In that same letter on pages 3 and 4, the licensee mentioned that a licensing basis review and evaluation has been performed. The staff requests that the licensee summarize the scope and results of the licensing basis review that was conducted, and plans for addreSSing RG 1.167, Section C.2.

(b) RG 1.167 states that "Holders of an operating license or construction permit issued prior to January 10, 1997, may voluntarily implement the methods described in this guide..." Discuss whether VEPCO plans to implement RG 1.167 and the referenced EPRI report, in their entirety. If not, identify all planned deviations from this guidance.

3. The staff requests that the licensee describe its long term plans for revaluating its design/licensing basis and updating the Final Safety Analysis Report for NAPS, Units 1 and

2. Further, the staff requests that the licensee provide a schedule for completion of these items and a justification for the proposed schedule.

Enclosure

- 2 Mechanical and Civil Engineering Supplemental Questions Short Term:

1. Nuclear Regulatory Commission Inspection Manual Part 9900, "Operability Determinations

& Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety," Section C.10, states that piping or pipe supports in a degraded or nonconforming condition should be evaluated in accordance with the criteria of Appendix F of the American Society of Mechanical Engineers (ASME) Boiler & Pressure Vessel (B&PV) Code,Section III, to demonstrate operability/functionality of the affected piping and supports. Confirm that the aforementioned Appendix F criteria have been utilized in the operability/functionality determination of piping and pipe supports which are required to be operable/functional. If the criteria of Appendix F have not been utilized in these operability determinations, please state the criteria or evaluation methods utilized to demonstrate operability/functionality of the piping and pipe supports in lieu of the Appendix F criteria. If sampling is utilized for analytical models for piping and pipe supports which are required to be seismically qualified by structural analysis, please discuss the criteria and methods of sampling that will ensure structural operability/functionality of the remainder population of piping and pipe supports.

Short Term and Long Term:

2. Discuss the method which will be used to identify welds for inspections and identify the type of inspections that will be performed for pre-restart and post-restart.

Long Term:

3. Discuss the post-restart (i.e., long-term) actions in place (Le., those included within the corrective action program) to evaluate seismically qualified piping and pipe supports, including those structures, systems, and components (SSCs) discussed on pages 4 and 5 of the September 17,2011, submittal, to demonstrate compliance with the licensing and design basis and/or applicable design basis code criteria/requirements, when these evaluations consider seismic loadings, {Operating Basis Earthquake (OBE) and DeSign Basis Eearthquake (DBE>> derived from the August 23, 2011, seismic event, combined with all other applicable load cases.

Piping Supplemental Questions Short Term:

Appendix 5A of the NAPS UFSAR, discusses the topic of fabrication flaws, (e.g. laminar tears, porosity, lack of fusion, fabrication induced cracking, etc.) that were detected in some of the NAPS steam generator supports and reactor coolant pump supports. The Updated Final Safety Analysis Report (UFSAR) appendix indicates that at least some of the flaws were subject to repairs at the facility. The UFSAR appendix states that ultrasonic testing (UT) methods are the proper non-destructive methods to use for detecting and sizing flaws of this nature. The UFSAR appendix also provided a flaw evaluation to support the licensee's conclusion that the flaws would be stable under the following types of assumed loading combinations: (1) static (dead weight) loads; (2) dynamic loads associated with the occurrence of five OBE events, as is assumed for in the deSign basis; (3) loads associated with an assumed loss of coolant accident

-3 (LOCA) pipe rupture plus those that would be imparted under the assumed DBE that was assumed in the design basis; and (4) possible pump vibratory loads, which are expected to be small in magnitude. The UFSAR appendix indicates that the emphasis was placed on the analysis of the flaws under the combined LOCA plus DBE loads for the facility.

It is not evident to the staff how many of the flaw indications mentioned in UFSAR, Appendix 5A for these supports were repaired or replaced as the appropriate corrective action for the components and how many of the flaws were left in service and justified for further service using the flaw tolerance evaluation that was included in UFSAR appendix. Provide the basis, using a detailed technical discussion, for why the current flaw evaluation in UFSAR, Appendix 5A is considered to be valid and bounding for evaluation of any relevant component support flaw indications that remain in service without repair, when compared to the option of requiring reanalysis of the flaws using the loadings from the LOCA event plus those that would have been imparted to the flaws from the August 2011 beyond-design-basis earthquake event. Justify why additional UT examinations of these component supports do not need to be imposed as a condition for restart of North Anna Unit 2 and for continued operation of these components supports.

Snubbers 1 The following is in regard to the previously issued snubber questions numbered 2 and 4, which were responded to in VEPCO's letters of October 3, 2011 (11-566) and October 10, 2011, (11-566A).

Short Term:

2. The second paragraph of the October 10,2011, response (11-566A), to snubber question 2, states: "These visual inspection results are consistent with the previous visual inspection performed in the spring of 2009." The last paragraph of the response to question 2 for Unit 2 states: "These visual inspection results are consistent with the previous visual inspections performed in spring 2010."

a. Provide additional details on the Unit 1 spring 2009 inspections results beyond just stating that they are consistent with previous examination results.

b. Provide details about any fourth inservice interval snubber examination and testing (based on the Technical Requirements Manual (TRM) program) for Unit 1 that may have been performed between Spring 2009 and Summer 2011. If no such snubber examination or testing was performed, provide the basis for that condition.

I To date, a response has not been provided to the long-term question from the September 28,2011, request for information. Please confirm that analyses will be performed to ensure the snubbers are designed (with appropriate factors of safety) to withstand loads comparable to or greater than that observed during the August 23, 2011 earthquake.

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c. Provide additional details on the Unit 2 spring 2010 inspections results beyond just stating that they are consistent with previous examination results.

d. The response to question 2 states that "The attachment lug will be repaired and the associated snubber will be replaced and functionally tested." Provide the date when this will be completed.

4. The second paragraph of the October 10, 2011, response to Snubber Question 4, states that:

In addition to the TRM functional test group for Unit 2, an additional twelve (12) small bore snubbers have been selected from Unit 1 for functional testing. This sample was developed based on a combination of various buildings/elevation, ease of access (ALARA, scaffold concerns, etc.), and snubbers expected to experience high loading during a seismic event. Also, two (2) large bore snubbers on Unit 1 will be tested. The Unit 1 snubber testing will be completed prior to entering Mode 4 on Unit 1. 2

a. Explain the method or evaluation that was performed to determine which snubber may have experienced higher loads during the seismic event at NAPS.

b. Explain the method or evaluation that was performed to identify snubbers that may have exceeded their design load capacity as a result of the August 23, 2011, seismic event felt at NAPS. Furthermore, discuss the prior-to-restart actions that will be taken to ensure proper operation for these snubbers.

d. Regarding the last sentence in the response to question 4 above, discuss the action to be taken, prior to entering Mode 4, if the snubber test results are unacceptable.

Pumps and Valves Short Term

1. Please discuss your inspections and evaluations to determine that all the safety-related pumps and valves (manual, AOVs, MOVs, POVs, RVs, and associated actuators) are operationally ready and functional following the August 23, 2011 earthquake. If no such inspections/evaluations were performed, please justify why they are not needed. Provide your response for each unit separately.

2. Discuss if each safety-related pump in your Inservice Testing (1ST) Program will be tested (Le" quarterly test, comprehensive test) in order to demonstrate operational readiness and functionality. If tests will not be performed for some pumps prior to restart, please discuss why they are not needed and how these pumps are judged to be operationally ready to perform their designated safety functions. Where tests will be performed, prior to restart, provide the results from this testing. Provide your response for each unit separately.

2 Also see question 2.b above.

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3. Discuss if each safety-related valve in your 1ST Program will be tested in order to demonstrate operational readiness and functionality. If tests will not be performed for some of these valves prior to restart, please discuss why they are not needed and how the valves are judged to be acceptable to perform their designated safety functions. Where tests will be performed, prior to restart, provide the results from this testing. Provide your response for each unit separately.

Long Term

4. Please discuss your planned approach and evaluations to confirm that appropriate design factors of safety are maintained if safety-related pumps and valves are subjected to seismic acceleration loads comparable to those observed during the August 23, 2011 earthquake.

Provide your response for each unit separately.

ML11285A359 I OFFICE I NRRJPM NRRJBC NRRJDORUDD I NAME I RMartin MKhanna AHowe I DATE I 10/13/11 10/13/11 10/13111