ML13134A371

5/9/2013 Summary of Telephone Conference Call Between the U.S. Nuclear Regulatory Commission and Tennessee Valley Authority, Concerning Requests for Additional Information Pertaining to the Sequoyah Nuclear Plant, Units 1 and 2, License Ren

ML13134A371
Person / Time
Site:	Sequoyah
Issue date:	06/13/2013
From:	Plasse R License Renewal Projects Branch 1
To:	James Shea Tennessee Valley Authority
References
TAC MF0481, TAC MF0482
Download: ML13134A371 (10)

Text

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LICENSEE: Tennessee Valley Authority FACILITY: Sequoyah Nuclear Plant, Units 1 and 2

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON MAY 9,2013, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND TENNESSEE VALLEY AUTHORITY, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC.

NOS. MF0481 AND MF0482)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Tennessee Valley Authority held a telephone conference call on May 9,2013, to discuss and clarify the staff's requests for additional information (RAls) concerning the Sequoyah Nuclear Plant, Units 1 and 2, license renewal application. The telephone conference call was useful in clarifying the intent of the staff's RAls.

Enclosure 1 provides a listing of the participants and Enclosure 2 contains a listing of the RAls discussed with the applicant, including a brief description on the status of the items.

The applicant had an opportunity to comment on this summary.

Richard A. Plasse, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328

Enclosures:

1. List of Participants

2. List of Requests for Additional Information cc w/encls: Listserv

... ML13134A371 OFFICE LA:DLR PM:RPB1:DLR BC:RPB1:DLR NAME IKing MYoo Y Diaz-Sanabria DATE 5/22/13 5/31/13 6/13/13 TELEPHONE CONFERENCE CALL SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION LIST OF PARTICIPANTS MAY 9,2013 PARTICIPANTS AFFILIATIONS Richard Plasse U.S. Nuclear Regulatory Commission (NRC)

Mark Yoo NRC Rui Li NRC Booma Venkataraman NRC Evelyn Gettys NRC Clifford Doutt NRC Henry Lee Tennessee Valley Authority (TVA)

Dennis Lundy TVA Roger Rucker TVA David Lach Entergy/Enercon Alan Cox Entergy/Enercon Enclosure 1

REQUESTS FOR ADDITIONAL INFORMATION SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 LICENSE RENEWAL APPLICATION May 9,2013 The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of Tennessee Valley Authority held a telephone conference call on May 9, 2013, to discuss and clarify the following requests for additional information (RAls) concerning the license renewal application (LRA).

8.1.21-1

Background:

In element 10 (operating experience) of the LRA AMP B.1.21, Metal Enclosed Bus Inspection, the applicant states that the MEB Program is a new program for which there is no operating experience at SQN involving the aging effects managed by this program. In the GALL Report AMP XI.E4, it states that industry operating experience has shown that failures have occurred on MEBs caused by cracked insulation and moisture or debris buildup internal to the MEB.

During the staff walk down on March 26, 2013, the staff became aware of a MEB failure event in 2009 that resulted in the tripping of both units. In problem event report (PER) 166884, the applicant states that the bus failed catastrophically on August 5,2009. The applicant determined that the failure of the bus was caused by cracked Noryl insulation and moisture intrusion inside the bus.

Issue:

The staff is concerned that a similar failure mode may occur in the MEBs during the extended period of operation. SQN operating experience may not support the applicant's conclusion that the program will be effective in managing the aging effect of MEBs for the period of extended operation.

Request:

1. Describe corrective actions taken or planned to prevent recurrence of MEB failure in the scope of license renewal.

2. Revise element 10 of the LRA to incorporate lessons learned from this OE and explain why LRA AMP B.1.21 will be effective in managing MEB aging mechanisms and effects.

Discussion: The staff determined that clarification was needed on the issue section of the question. The staff will reword the issue section to better clarify and capture the staff's concern that the current plant-specific operating experience may not ensure the effectiveness of the aging management program for the period of extended operation. As a result of the discussion, the staff has replaced the issue section of the question with the following:

Based on the MEB failure identified in PER 166884, the staff is concerned that SQN operating experience may not support the applicant's conclusion that LRA AMP B.1.21 will be effective in managing the aging effect of MEBs for the period of extended operation.

The staff also determined that clarification was needed on the request section of the question to increase the specificity and focus. As a result of the discussion, the staff has replaced the request section of the question with the following:

1. Describe corrective actions taken or planned to prevent recurrence of a MEB failure within the scope of license renewal.

2. Revise element 10 of the LRA to incorporate lessons learned from this OE and explain why LRA AMP B.1.21 will be effective in managing MEB aging effects.

8.1.21-2

Background:

During the review of a plant procedure, SQN-1-Bus-202-CC/CE, the staff identified an issue with verifying proper torque. Section 5.7.e of the procedure requires verifying bolts are properly torqued. EPRI TR-104213, Bolted Joint Maintenance & Application Guide, states that bolts should not be retorqued unless the joint requires service or the bolts are clearly loose. Verifying the torque is not recommended. The torque required to turn the fastener in the tightening direction (restart torque) is not a good indicator of the preload once the fastener is in service.

Due to relaxation of the parts of the jOint, the final loads are likely to be lower than the install loads. The GALL AMP XI.E4 recommends checking bus connections for increased resistance by using thermography or by measuring connection resistance using a micro-ohmmeter.

Issue:

Re-torque is not recommended per industry guidance.

Request:

1. Explain the practice used to perform torque checks verses the industry recommended practice not to re-torque once the fastener is in service.

2. Describe corrective action taken to prevent the re-torque practice.

Discussion: The staff determined that clarification was needed on the request section of the question. The staff determined that the two requests can be rewritten as one request to better organize the question. As a result of the discussion, the staff has replaced the request section of the question with the following:

Explain why procedure SQN-1-Bus-202-CC/CE requires the verification that bolts are properly torqued versus the industry recommended practice not to retorque once the fastener is in service.

RAI 8.1.25-1

Background:

NUREG-1801. Rev. 2. "Generic Aging Lessons Learned." (the GALL Report) addresses inaccessible power cables in Aging Management Program (AMP) XLE3. "Inaccessible Power Cables Not Subject to 10 CFR 50.49 Environmental Qualification Requirements." The purpose of this aging management program (AMP) is to provide reasonable assurance that the intended functions of inaccessible or underground power cables (400V to 35 kV), that are not subject to environmental qualification requirements of 10 CFR 50.49 and are exposed to wetting or submergence will be maintained consistent with the current licensing basis. The scope of the program applies to inaccessible (e.g. in conduit, duct bank. or direct buried installations) power cables within the scope of license renewal that are subject to significant moisture. Significant moisture is defined as periodic exposures to moisture that last more than a few days (e.g. cable wetting or submergence in water). NUREG- 1800, Rev. 2 "Standard Review Plan for Review of License Renewal Applications for Nuclear Power Plants," (SRP), Table 3.0-1 provides guidance for FSAR Supplements for aging management of applicable systems including the GALL Report AMP XLE3.

Industry operating experience provided by NRC licensees in response to GL 2007-01 has shown: (a) that there is an increasing trend of cable failures with length in service. (b) that the presence of water/moisture or submerged conditions appears to be the predominant factor contributing to inaccessible or underground power cable failure. The staff has determined, based on the review of the cable failure data, that an annual inspection of manholes and a cable test frequency of at least every 6 years (with evaluation of inspection and test results to determine the need for an increased inspection or test frequencies) is a conservative approach to ensure the operability of power cables and, therefore, should be considered.

In addition, industry operating experience has shown that some NRC licensees have experienced cable manhole water intrusion events, such as flooding or heavy rain, that subjects cables within the scope of GALL Report, AMP XI.E3 to significant moisture. The staff has determined that event driven inspections of cable manholes, in addition to the one year periodic inspection frequency, is a conservative approach and. therefore, should be considered. The GALL Report AMP XI,E3 states that periodic actions should be taken to prevent inaccessible cables from being exposed to significant moisture. Examples of periodic actions are inspecting for water collection in manholes and conduits and draining water as needed. The inspection should include direct observation that cables are not wetted or submerged, and cables/spices and cable support structures are intact, and that dewatering/drainage systems (sump pumps) and associated alarms operate properly.

Issue:

During review of the applicant's operating experience, including work orders, problem evaluation reports (PERs), and inspection reports, the staff identified unresolved cases of unacceptable levels of water in manholes and hand-holes which could potentially expose in-scope power cables to significant moisture.

When a power cable is exposed to wet or submerged conditions for which it is not deSigned, an aging effect of reduced insulation resistance may result, causing a decrease in the dielectric strength of the conductor insulation. This insulation degradation caused by wetting or

submergence can potentially lead to failure of the cable's insulation system. Sequoyah inaccessible power cable operating history includes reference to PERs 432510,585074, 589672,622595, 432510, and letter dated March 12,2013 to S.L. Harvey, "Response to Corporate Oversight- Level 1 Escalation letter (ERCW Duct bank dewatering efforts)", that identify unresolved concerns with standing water and timely dewatering of manholes. NRC Integrated Inspection Report 05000327/2012002, 05000328/2012002 identified a green finding for the applicant's failure to meet the requirements of corrective action program procedure NPG SPP-03.1.7, PER Actions, Revision 2. The finding involved the applicant's failure to ensure that the corrective action plan and associated actions addressed the required action and schedule associated with PER 432510. The issue was entered into the applicant's corrective action program as PERs 433761, 432510, and 505259.

The staff is concerned that the applicant's manhole inspections, including maintenance of sump pumps and cable support structures may not be adequate to prevent in-scope inaccessible power cables form being subjected to significant moisture. Additional information is required before a determination can be made regarding the sufficiency of LRA AMP B.1.25 to detect and manage the effects of aging.

Requests:

1. Additional information is required that demonstrates proactive and satisfactory manhole, sump pump, and cable support structure inspection, maintenance and corrective actions to prevent in-scope inaccessible power cables from being exposed to significant moisture.

a) Include a summary discussion of corrective actions and schedule for completion.

2. Describe how plant specific and industry operating experience will be evaluated and incorporated into the GALL Report LRA AMP B.1.25 to prevent exposure of in-scope inaccessible power cables to significant moisture before and during the period of extended operation.

3. Describe inaccessible power cable testing, test frequencies and test applicability that demonstrate that in-scope inaccessible power cables, including inaccessible low voltage power cable, will continue to perform their intended function before and during the period of extended operation.

Discussion: The staff and the applicant discussed the clarification of request 2 and 3. As a result of this discussion, no action was required.

RAI E-1

Background:

In the LRA Appendix 8.1.21, B.1.24, 8.1.25, 8.1.26 and B.1.27, under Element 10 (operating experience), the applicant states that these AMPs are new programs and that industry operating experience will be considered in the implementation of this program. The applicant also stated that plant operating experience will be gained as the program is executed and will be factored into the program via the confirmation and corrective action elements of the SON 10 CFR 50 Appendix B quality assurance program. The applicant further stated in LRA B.1.21 that there is no operating experience at SON involving the aging effects managed by these programs. The

applicant concluded that there is reasonable assurance that these new aging management programs will be effective during the period of extended operation.

SRP-LR Section A.1.2.3.1 0 states that for new AMPs that have yet to be implemented at an applicant's facility, the programs have not yet generated any operating experience (OE).

However, there may be other relevant plant-specific OE at the plant that is relevant to the AMP's program elements even though the OE was not identified as a result of implementation of the new program. Thus, for new programs, an applicant may need to consider the impact of relevant OE that results from the past implementation of its existing AMPs that are existing programs and the impact of relevant generic OE on developing the program elements.

Therefore, operating experience applicable to a new program should be discussed. In the License Renewal Interim Staff Guidance (LR-ISG) 2011-05, the staff stated that it intends for the ongoing review of operating experience to inform every AMP, regardless of the AMP's implementation schedule. The staff noted that there were instances of operating experiences relating to electrical AMPs which were not discussed in the OE program element. For example, a metal enclosed bus failed in August 2009 which resulted in the tripping of both units. The failure of the bus was caused by cracked Noryl insulation and moisture intrusion inside the metal enclosed bus. This represents plant specific operating experience directly applicable to the aging mechanisms and effects relating to the metal enclosed bus program AMP.

Issue:

Reviewing OE should be on an ongoing review basis to ensure the effectiveness of license renewal AMPs.

Request:

1. Describe relevant plant specific OE and lessons learned, as discussed above, for each electrical AMP.

2. Identify areas where the aging management program was enhanced.

3. Revise the LRA Appendix B operating experience elements, as appropriate.

4. The operating experience being considered should include plant-specific OE at the plant that is relevant to the AMP's program elements even though the OE was not identified as a result of implementation of the program.

Discussion: The staff determined that clarification was needed on the issue section of the question. The applicant noted that the background and request section of the question focuses on current plant-specific operation experience, but the issue section focuses on future plant specific operating experience. As a result of the discussion, the staff has replaced the issue section of the question with the following:

Operating experience from existing plant programs relevant to LRA Appendix B, AMPs B.1.21, B.1.24, B.1.25, B.1.26 and B.1.27 are not provided in the LRA. For new AMPs, applicable plant specific and generic OE should be considered on an ongoing review basis to ensure the effectiveness of the new AMP' program elements.

The staff also determined that clarification was needed on the request section of the question.

As a result of the discussion, the staff has replaced the request section of the question with the following:

The operating experience (OE) being considered should include plant-specific OE at the plant that is relevant to the AMP's program elements even though the OE was not identified as a result of implementation of the program.

1. Describe relevant plant specific OE and lessons learned, as discussed above, for each electrical AMP.

2. Identify areas where the AMP was enhanced.

3. Revise the LRA Appendix B OE elements, as appropriate.

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON MAY 9, 2013, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND TENNESSEE VALLEY AUTHORITY, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2, LICENSE RENEWAL APPLICATION (TAC.

NOS. MF0481 AND MF0482)

DISTRIBUTION:

HARDCOPY:

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PUBLIC RidsNrrDlr Resource RidsNrrDlrRpb1 Resource RidsNrrDlrRpb2 Resource RidsNrrDlrRerb Resource RidsNrrDlrRarb Resource RidsNrrDlrRasb Resource beth.mizuno@nrc.gov <OGC>

brian.harris@nrc.gov <OGC>

john.pelchat@nrc.gov <gov't liaison officer>

gena.woodruff@nrc.gov <gov't liaison officer>

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galen.smith@nrc.gov <res insp>

scott.shaeffer@nrc.gov (RII) jeffrey. hamman@nrc.gov (RII) craig.kontz@nrc.gov (RII) caudle.julian@nrc.gov (RII) generette.lloyd@epa.gov (RIV gmadkins@tva.gov clwilson@tva.gov hleeO@tva.gov dllundy@tva.gov