ML13192A035

Tennessee Valley Authority - Reply to Notices of Violation; EA-13-023 and EA-13-045

ML13192A035
Person / Time
Site:	Sequoyah
Issue date:	07/03/2013
From:	Shea J W Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
EA-13-023, EA-13-045
Download: ML13192A035 (15)

Text

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402July 3, 201310 CFR 2.201ATTN: Document Control DeskU.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2Facility Operating License Nos. DPR-77 and DPR-79NRC Docket Nos. 50-327 and 50-328

Subject:

Reply to Notices of Violation; EA-13-023 and EA-13-045

References:

1. Letter from NRC to TVA, "Sequoyah Nuclear Plant -NRC Inspection Report05000327/2013009, 05000328/2013009; Preliminary Yellow Finding, andApparent Violations,"

dated March 12, 20132. Letter from NRC to WVA, "Sequoyah Nuclear Plant -NRC Inspection Report05000327/2013010, 05000328/2013010; Preliminary Greater Than GreenFinding and Apparent Violation,"

dated March 18, 20133. TVA Nuclear Power Group Hydrology Regulatory Conference slides(ADAMS Accession No. ML1 3115A020)

4. Letter from NRC to TVA, "Sequoyah Nuclear Plant -Final Significance Determination of White Finding, Notices of Violations, and Assessment Follow-up Letter: NRC Inspection Report No. 05000327/2013011, 05000328/2013011,"

dated June 4, 2013In accordance with NRC letters dated March 12, 2013 (Reference

1) and March 18, 2013(Reference 2), Tennessee Valley Authority (TVA) requested a Regulatory Conference todiscuss the apparent violations documented in References 1 and 2. The Regulatory Conference was conducted on April 22, 2013, during which TVA made a presentation on theissues (Reference 3). Subsequently, the NRC issued Notices of Violation EA-13-023 andEA-13-045 on June 4, 2013 (Reference 4). In accordance with the NRC's June 4, 2013letter, TVA is required to respond to the Notices of Violation within 30 days of the date of theletter.Printed on recycled paper U.S. Nuclear Regulatory Commission Page 2July 3, 2013TVA's response to these Notices of Violation is provided in Enclosures 1 (EA-1 3-023) and 2(EA-13-045) in accordance with 10 Code of Federal Regulations (CFR) 2.201, "Notice ofViolation."

There is one regulatory commitment contained in this response.

This commitment isidentified in Enclosure

3. Should you have any questions concerning this submittal, pleasecontact M. W. McBrearty, Nuclear Site Licensing

Manager, at (423) 843-7170.

Respecif y,S'fSheaicPresident, Nuclear Licensing

Enclosures:

1. Reply to a Notice of Violation; EA-13-023

2. Reply to a Notice of Violation; EA-13-045

3. List of Regulatory Commitments cc (Enclosures):

NRC Regional Administrator

-Region IINRC Senior Resident Inspector

-Sequoyah Nuclear Plant ENCLOSURE ITennessee Valley Authority Sequoyah Nuclear Plant, Units 1 and 2Reply to a Notice of Violation; EA-13-023 Reply to a Notice of Violation; EA-13-023 Restatement of Violation ATechnical Specification 6.8.1, "Procedures and Programs,"

requires in part that writtenprocedures shall be established, implemented, and maintained covering the activities recommended in Regulatory Guide 1.33 [Quality Assurance Program Requirements (Operations)],

Revision 2, Appendix A, February 1978.Regulatory Guide 1.33, Revision 2, Appendix A, includes "Abnormal Conditions" as a typicalsafety-related activity that should be covered by written procedures.

Abnormal operating procedure AOP-N.03, "External Flooding,"

Revision 29, providesdetailed instructions for implementing required site flood mitigation strategies necessary tocope with design basis flooding events.Contrary to the above, prior to September 30, 2009, the licensee failed to establish anadequate Abnormal Condition Procedure to implement its flood mitigation strategy.

Specifically, AOP-N.03, "External Flooding,"

was inadequate to mitigate the effects of aProbable Maximum Flood (PMF) event, in that earthen dams located upstream of the facilitycould potentially

overtop, causing a subsequent breach. Failure of the earthen dams duringa PMF event would have resulted in onsite flooding and subsequent submergence of criticalequipment, such as the Emergency Diesel Generators, resulting in an ineffective floodmitigation strategy for these PMF events.Background It was determined on July 28, 2009, that an upstream dam (Fort Loudoun) would overtopand fail during a design basis PMF. Subsequent to this date, it was discovered thatCherokee,

Tellico, and Watts Bar dams had a similar design vulnerability that would alsoresult in a higher flood elevation at the SQN site.TVA performed an analysis and determined that the overtopping and failure of the specified earthen embankments would have resulted in an increase in the PMF level at SequoyahNuclear Plant (SQN) and would have the potential to affect systems required for safeshutdown.

The overtopping of the dams represented an unanalyzed condition.

Subsequent analysis determined that the calculated increase in flood level at SQN from a PMF event inwhich the specified earthen embankments were overtopped and failed rendered existingflood mode procedures ineffective.

In July and August 2009, TVA implemented interim compensatory measures to mitigateimpacts of the potential dam overtopping issues. TVA modified River Operations procedures were modified to notify SQN if 5 inches or greater average rainfall over 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />soccurs over the watershed above the Fort Loudoun and Tellico dams. At the same rainfallthreshold, TVA procedures required the mobilization of the necessary heavy equipment toremove the Fort Loudoun Marina Saddle dam to preserve the integrity of Fort LoudounDam. In this same time period, TVA commenced installation of the Hercules Engineering Solutions Consortium (HESCO) barriers on the Fort Loudoun,

Tellico, Watts Bar, andCherokee dams. These modifications were implemented to effectively raise damembankments 3 feet to 8 feet, which prevent flood overtopping and potential impacts to thedam earthen embankments and possible

failure, and protect critical SQN facility operations.

E1-1 of 6 Reply to a Notice of Violation; EA-13-023 By December 30, 2009, the HESCO barriers installation was completed.

Post-HESCO PMFcalculations were issued for SQN to bring SQN into compliance with the licensed conditions.

Reason for the Violation The reasons for this violation are as follows.* The Simulated Open Channel Hydraulics (SOCH) model had design input errors dueto overconfidence in the adequacy of the model and in the calculation process.

Thisresulted in unrecognized inaccuracies in the nuclear plant PMF calculations.

• Nuclear Power Group management failed to ensure a sufficient focus on nuclearsafety with regard to flooding by failing to provide effective oversight andengagement on changes being made to the river system in order to ensure thatpotential impacts on the SQN flooding design basis were properly evaluated.

• Formal flood protection programmatic and process controls had not been established for the protection of critical safety systems at SQN.* Nuclear Power Group personnel had less than adequate common internalunderstanding of the applicable regulatory requirements for SQN with respect to riversystem operation controls.

• Ineffective completion of the Bellefonte Nuclear Plant corrective actions.Corrective Steps That Have Been Taken and Results AchievedThe installation of HESCO barriers on the Fort Loudoun,

Tellico, Watts Bar, and Cherokeedams has been completed to raise the effective height of the earthen embankments.

Post-HESCO PMF calculations have been issued for SQN to bring SQN into compliance with the licensed conditions.

An Integrated Hydrology Advisory Committee has been implemented.

The committee wasformed to identify,

discuss, and disposition common issues and initiatives relating to TVAhydrology.

In addition, the implementing procedure, TVA-SPP-20.009, "Coordination ofHydrology Issues,"

has been issued. This procedure applies to TVA organizations.

Issuesand initiatives relating to TVA hydrology are included in the scope of this procedure.

Procedure NEDP-20, "Conduct of the E~ngineering Organization,"

has been revised toinclude a Flood Protection Program within the Corporate Nuclear Engineering organization.

The primary function of the Flood Protection Program is to ensure that nuclear plant criticalsafety systems are protected from all postulated flooding conditions.

E1-2 of 6 Reply to a Notice of Violation; EA-13-023 Corrective Steps That Will Be TakenIn addition to the corrective steps that have already been taken, the following corrective steps remain to be taken." Procedures will be developed or revised to implement the Corporate NuclearEngineering Flood Protection Program described above. The implementing procedures will ensure that nuclear plant critical safety functions are protected frompostulated flooding conditions, and will include appointing a single-point owner,defining roles and responsibilities, and identifying the nuclear regulatory requirements.

" Procedural requirements will be established to include reviews by TVA NuclearPower Group of any river or dam changes, including calculations that may affect theCorporate Nuclear Engineering Flood Protection Program." A formal risk management

process, informed by Institute of Nuclear PowerOperations (INPO)12-008, "Excellence in Integrated Risk Management,"

for allflood-related engineering products will be created.

The process will ensure changesare evaluated to nuclear plant design standards, river system operations, flood-related procedures, project management procedures, and applicable environmental standards.

" An inventory of nuclear programs and processes that are important to nuclear safetywill be developed.

The programs and processes will be prioritized in order of relativerisk or importance to safety, and controlling procedures to assure nuclear safety willbe verified to exist. This inventory of programs and processes will be reviewed on abiennial basis and updated, as necessary.

Date When Full Compliance Will Be AchievedFull compliance was achieved on December 30, 2009 for the failure to establish and/ormaintain an adequate Abnormal Condition Procedure to implement its flood mitigation strategy violation as described in EA-13-023.

On this date the HESCO barrier installation was completed to raise the effective height of the earthen embankments and thepost-HESCO PMF calculation was issued for SQN, placing SQN in compliance with thelicensed conditions.

E1-3 of 6 Reply to a Notice of Violation; EA-13-023 Restatement of Violation B10 CFR 50.72(b)(3)(ii)(B) states that a licensee shall notify the NRC as soon as practical and in all cases within eight hours of the occurrence of the nuclear plant being in anunanalyzed condition that significantly degraded plant safety.Contrary to the above, on December 30, 2009, the licensee failed to report within eighthours an unanalyzed condition that significantly degraded plant safety for the Sequoyahfacility.

Specifically, the licensee failed to notify the NRC upon confirmation that a postulated Probable Maximum Flood (PMF) level would exceed the current licensing basis and thedesign basis PMF flooding event would result in overtopping of critical earthen damstructures upstream of the Sequoyah facility.

These overtopping conditions were notpreviously assumed in the licensing basis for the facility and represented an unanalyzed condition.

Background

It was determined on July 28, 2009, an upstream dam (Fort Loudoun) would overtop and failduring a design basis PMF. Subsequent to this date, it was discovered that Cherokee,

Tellico, and Watts Bar dams had a similar design vulnerability that would also result in ahigher flood elevation at the site. This condition had the potential to exceed the licensing basis PMF levels at SQN and adversely impact safety functions at the plant. The increasein PMF placed the plant in an unanalyzed condition.

Nuclear Power Group personnel failedto recognize that this condition was required to be reported to the NRC by 10 CFR50.72(b)(3)(ii)(B).

During the period from 2010 to present, TVA's communication with the NRC on this issueincluded public meetings, letters and correspondence, License Event Reports, LicenseAmendment

Requests, a Confirmatory Action Letter, and numerous email and telephone communications.

Communication by TVA with the NRC concerning SQN being in anunanalyzed condition (prior to installation of the HESCO barriers) did not take the form of aformal notification by SQN as required by 10 CFR 50.72, until TVA reported the condition inaccordance with 10 CFR 50.72 on February 6, 2013, resulting in impediments to NRCprocesses.

Reason for the Violation The reasons for this violation are as follows.* The nuclear processes and procedures failed to lead TVA to realize, in 2009, thatinvalidated assumptions in calculations of PMF levels constituted a reportable unanalyzed condition that significantly degraded plant safety. In the period from2009 through 2012, TVA procedure inadequacies did not require Functional Evaluations to address reportability, nor did reporting procedures fully incorporate regulatory guidance on reportability.

" Nuclear Power Group personnel had a cultural bias towards not reporting events andconditions when the consequences of an event or condition were uncertain and notfully analyzed.

E1-4 of 6 Reply to a Notice of Violation; EA-13-023

• Nuclear Operations, Engineering, and Licensing personnel were weak inunderstanding unanalyzed conditions and the relationship to reportability.

• An erroneous, centralized decision was made within TVA Corporate NuclearLicensing that the calculated PMF levels and their potential impacts on SQN werenot reportable because of the uncertainties in the calculations.

• Nuclear Power Group personnel failed to adequately challenge the decision that theissue was not reportable.

Corrective Steps That Have Been Taken and Results AchievedAs stated above, TVA made a 10 CFR 50.72(b)(3)(ii)(B) notification on February 6, 2013(Emergency Notification Report 48725).A structured oversight program to assess reportability decisions has been developed.

Thisoversight program requires a review of the reportability determinations of at least 10 percentof the TVA Nuclear Power Group fleet problem evaluation reports (PERs) on a bi-weekly basis.Corrective Steps That Will Be TakenIn addition to the corrective steps that have already been taken, the following corrective steps remain to be taken.* Procedure NPG-SPP-03.5, "Regulatory Reporting Requirements,"

will be revised to:include the requirements of NUREG-1022, Revision 3 and examples of whatconstitutes an unanalyzed condition; include direction to refer to Section 2 ofNUREG-1 022 for special conditions on reportability; and ensure that when usingengineering

judgment, conservative decision-making is applied (i.e., if there is doubtregarding whether to report or not, the report should be made).* Procedure NEDP-22, "Functional Evaluations,"

will be revised to address if a defectis outside current licensing basis and/or design basis (i.e., an unanalyzed condition exists).

If such a situation exists, the procedure will provide that the reportability ofthe defect should be determined.

• The above described revisions to NPG-SPP-03.5 and NEDP-22 will be incorporated into Operations, Engineering, and Licensing training.

• Broad scope reportability program training will be conducted for key organizations with reporting responsibilities.

• A case study on hydrology and flooding reporting decision errors will be developed for the INPO Significant Operating Experience Report (SOER) 10-2 trainingconducted this year. Included in the case study will be the dangers of group think,the need for rigor and oversight, and the use of risk in decision making that mayaffect nuclear safety.E1-5 of 6 Reply to a Notice of Violation; EA-13-023

• The structured oversight program described in the corrective steps that have beentaken will be maintained for a minimum of one year.E1-6 of 6 Reply to a Notice of Violation; EA-13-023 Date When Full Compliance Will Be AchievedFull compliance was achieved on February 6, 2013 for the failure to report in accordance with 10 CFR 50.72(b)(3)(ii)(B) violation described in EA-13-023, when the event wasreported to the NRC (Event Notification Report 48725).E1-7 of 6 ENCLOSURE 2Tennessee Valley Authority Sequoyah Nuclear Plant, Units I and 2Reply to a Notice of Violation; EA-13-045 Reply to a Notice of Violation; EA-1 3-045Restatement of Violation 10 CFR 50, Appendix B, Criterion Ill, "Design Control,"

states in part, that measures shall beestablished to assure that applicable regulatory requirements and the design basis asspecified in the license are correctly translated into specifications,

drawings, procedures, and instructions.

The Sequoyah licensing basis related to onsite flooding is specified in UFSAR Section 2.4,"Hydrologic Engineering" and states in part, that the Essential Raw Cooling Water (ERCW)Intake Station will be maintained dry during a Design Basis Flood (DBF).UFSAR Section 2.4.2.2, "Flood Design Considerations" states, "Protective measures aretaken to ensure that all safety-related systems and equipment in the ERCW pump stationwill remain functional when subjected to the maximum flood level."UFSAR Section 2.4A.2.1, "Flooding of Structures" states, "Only the Reactor Building, theDiesel Generator Building (DGB), and the Essential Raw Cooling Water Intake Station willbe maintained dry during the flood mode. Walls and penetrations are designed to withstand all static and dynamic forces imposed by the DBF."Contrary to the above, prior to December 15, 2012, the licensee failed to translate thedesign basis related to onsite flooding into specifications,

drawings, procedures, andinstructions.

Specifically, Sequoyah's existing design documentation including currentlicensing documents and configuration controlled drawings for the ERCW Pumping Stationdo not contain information to identify Design Basis flood barriers to prevent water fromflooding the building during a design basis flood affecting the ERCW strainer motors. As aresult, the ERCW pump station would not remain functional when subjected to the maximumflood level, the ERCW Intake Station would not remain dry during flood mode, and portionsof the ERCW walls and penetrations would not withstand all static and dynamic forcesimposed by the DBF.Background The licensing basis for the Sequoyah Nuclear Plant (SQN) ERCW Intake Station requiresthe structure be maintained dry during a DBF. The original design criteria established forconstruction were consistent with this licensing basis. Specifically, the 1971 revision ofapplicable design criteria (currently titled SQN-DC-V-12.4, "Cable Support Systems forCapability of Testing Cables for the Design Basis Flood") included a requirement for theelectrical cables in the manholes leading up to the ERCW building to be sealed andpressure tested prior to licensing.

That test required the manholes to be filled with waterand pressurized.

To be able to perform this test each of the manholes and hand holeswould have to be water tight. This was accomplished with metal plate covers over themanholes.

However, in 1974 a revision of SQN-DC-V-12.4 removed the test requirement, allowing subsequent changes to manhole covers, including removal.

A separate designcriteria, SQN-DC-V-1 2.1, "Flood Protection Provisions,"

provided that the ERCW PumpingStation was to remain dry during a design basis event. However, it does not identify barriersor other means to ensure the ERCW Pumping Station remains dry. TVA determined thatdesign documentation existing in 1978 for the initial construction of the ERCW PumpingE2-1 of 3 Reply to a Notice of Violation; EA-13-045 Station lacked clear information regarding the ERCW Pumping Station design basis floodboundaries.

In 1980, an engineering change added a note to an ERCW Pumping Station control drawing35W830-4, "Conduit and Grounding Drawing,"

referencing a generic Fire Penetration drawing 45W880-26, "Conduit and Grounding Cable Trays Fire Stop Penetrations,"

forsealing instructions of a similar electrical conduit cover. This incident resulted in a loss ofconfiguration control for the ERCW Pumping Station flood barriers.

The fire penetration drawing 45W880-26, contained many sealing details, with some of the sealing details notpertaining to flooding barriers.

Subsequent changes to the fire penetration seal drawing inthe mid 1980s led to substitution of conduit seals and fittings.

The fire penetration drawingdid not specify particular seals to be watertight until 1986, even after which, no supporting sealing analysis existed for design basis flood application.

In 1991, an engineering change allowed a 1-inch access hole in the manhole missile shieldsto assist in determining if the manholes or hand holes had been flooded.

It was documented in the change that there is no requirement for periodic pressuring testing of the manholesand hand holes, thus their associated covers were removed.

This resulted in conduit sealsas the only barrier against a flood above plant grade, even though the seals may have beeninadequate.

In September 2012, during a Near Term Task Force (NTTF) walk-down, TVAidentified that a potential existed for water in-leakage into the ERCW Pumping Stationduring a flood above plant grade through manhole 33. A subsequent review of the issuedetermined the condition to be degraded and non-conforming with the licensing basis, andcompensatory measures were developed.

Also, a design change was initiated to provideadequate conduit seals for the conduit penetrations located inside manhole 33. OnDecember 12, 2012, pre-modification work was conducted to inspect and document the as-found condition of the conduits in manhole 33. At this time, TVA discovered that the ERCWPumping Station was at risk of flooding during a flood event due to conduit penetrations notbeing filled with material required to make the building watertight.

Upon this discovery, TVAnotified the NRC of the unanalyzed condition (Emergency Notification Report 48584) andinstalled additional sump pumps in the ERCW Pumping Station.Reason for the Violation The reason for this violation is that the ERCW penetration seals were described in generaldesign documents, but their functional requirements were not specifically addressed inoriginal design documents.

Corrective Steps That Have Been Taken and Results AchievedAdditional sump pumps in the ERCW Pumping Station have been installed to assist inmitigating water in-leakage in the event of a DBF.Two open conduits identified on the north side of the ERCW Pumping Station have beensealed.New penetration seals have been installed in manhole 33 to address the initial problem.E2-2 of 3 Reply to a Notice of Violation; EA-13-045 Corrective Steps That Will Be TakenIn addition to the corrective steps that have already been taken, the following corrective steps remain to be taken." A comprehensive design basis document will be developed to fully address externalflooding protection for the ERCW building.

• New exterior flood barrier drawings for the ERCW building will be issued that identifyexterior flood boundaries and contain penetration seal details.Date When Full Compliance Will Be AchievedFull compliance will be achieved by October 1, 2013 for the violation of the failure of existingERCW Pumping Station design documentation, including current licensing basis documents and configuration-controlled

drawings, to contain information to identify design basis floodbarriers to prevent water from flooding the ERCW building during a design basis flood. Fullcompliance will be achieved by the inclusion of the new design basis documentation andconfiguration controlled drawings showing design basis flood barriers and penetration sealdetails for the ERCW Pumping Station building in SQN design criteria standards.

E2-3 of 3 ENCLOSURE3 List of Regulatory Commitments

1. Tennessee Valley Authority will revise the Essential Raw Cooling Water (ERCW)Pumping Station building design basis documents and configuration controlled drawingsto clearly identify design basis flood barriers and penetration seal details by October 1,2013.E3-1 of 1