ML13085A219
| ML13085A219 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 03/21/2013 |
| From: | Hruby R A Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC ME7713 | |
| Download: ML13085A219 (10) | |
Text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000March 21, 201310 CFR 50.36U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, D.C. 20555-0001Watts Bar Nuclear Plant, Unit 2NRC Docket No.50-391Subject: Watts Bar Nuclear Plant, Unit 2 -Response to Request for AdditionalInformation Regarding Technical Specifications Changes -Instrumentation and Controls Branch (TAC No. ME7713)References: 1. NRC letter to TVA dated March 13, 2013, "Watts Bar Nuclear Plant,Unit 2 -Request for Additional Information Regarding TechnicalSpecifications Changes -Instrumentation and Controls Branch(TAC No. ME7713)" [ML13037A265]2. TVA letter to NRC dated June 21, 2011, "Watts Bar Nuclear Plant (WBN)Unit 2 -Response to NRC Staff Comments on Developmental Revisionsof the Unit 2 Technical Specifications (TS) and Technical SpecificationsBases (TS Bases); Submittal of Developmental Revision F"3. TVA letter to NRC dated October 5, 2010, "Watts Bar Nuclear Plant(WBN) Unit 2 -Instrumentation and Controls Staff Information Requests"4. TVA letter to NRC dated May 13, 2010, "Watts Bar Nuclear Plant (WBN)Unit 2 -Transmittal of TVA EEB-TI-28, Branch Technical Instruction,'Setpoint Calculations"'The purpose of this letter is to respond to the NRC Request for Additional Information (RAI)related to the Technical Specifications (TS) on the Reactor Trip System and the EngineeredSafety Features Actuation System provided in Reference 1. TVA's response is provided inthe enclosure to this letter.
U.S. Nuclear Regulatory CommissionPage 2March 21, 2013There are no new regulatory commitments contained in this letter. The enclosed responseprovides information that satisfies commitments 2 and 3 of Enclosure 9 to Reference 2. Ifyou have any questions, please contact Gordon Arent at (423) 365-2004.I declare under penalty of perjury that the foregoing is true and correct. Executed onthe 21st day of March, 2013.Respectfully,Raymond A. Hruby, Jr.General Manager, Technical ServicesWatts Bar Unit 2Enclosure: Response to a Request for Additional Information, Watts Bar Nuclear PlantUnit 2 Regarding Technical Specifications Changes, Instrumentation andControls Branchcc (Enclosure):U. S. Nuclear Regulatory CommissionRegion IIMarquis One Tower245 Peachtree Center Ave., NE Suite 1200Atlanta, Georgia 30303-1257NRC Resident Inspector Unit 2Watts Bar Nuclear Plant1260 Nuclear Plant RoadSpring City, Tennessee 37381 RESPONSE TO A REQUEST FOR ADDITIONAL INFORMATIONWATTS BAR NUCLEAR PLANT. UNIT 2 REGARDINGTECHNICAL SPECIFICATIONS CHANGESInstrumentation and Controls BranchGENERAL RESPONSEWBN Unit 2 FSAR Section 7.1.2.1.9 discusses Trip Setpoints. TVA has used TechnicalSpecification Task Force (TSTF) 493 Revision 4 for setpoints in the Reactor Trip System (RTS)and the Engineered Safeguards Features Actuation System (ESFAS). Westinghouseestablishes the values for most of the associated features and the methods and values areprovided in WCAP-17044-P, 'Westinghouse Setpoint Methodology for Protection Systems,Watts Bar Unit 2." Setpoints developed by TVA are performed using the methodologydescribed in TVA Technical Instruction (TI) TVA EEB TI-28. The NRC reviewed the setpointmethodology used for WBN Unit 2 in Supplemental Safety Evaluation Report (SSER) 23. Theconclusions from SSER 23 are summarized in the following:"By letter dated September 1, 2010 (ADAMS Accession No. ML1 02530216), TVAsubmitted WBN Unit 2 FSAR Amendment 100. In this amendment, TVA discussed indetail the setpoint methodology used by TVA and Westinghouse to calculate instrumentsetpoints for the RPS and the ESFAS. In response to staff questions about variousaspects of the instrument setpoint methodology used by TVA and Westinghouse, TVAprovided additional information by letter dated October 29, 2010 (letter open items 306through 311; ADAMS Accession No. ML103120711). By letter dated December 17,2010 (ADAMS Accession No. ML1 10070327), TVA incorporated the reviseddescription of instrument setpoint methodologies used by TVA and Westinghouse intoFSAR Amendment 102. TVA's description is consistent with Technical SpecificationTask Force (TSTF)-493, Revision 4, "Clarify Application of Setpoint Methodology forLSSS Functions," which was reviewed and accepted by the NRC staff by letter datedMay 11, 2010 (ADAMS Accession No. ML100710442). TVA also stated in the FSARthat "Single-sided correction factors are not used in setpoint calculations within thescope of TSTF-493." Based on its review of WBN Unit 2 FSAR Amendment 102, theNRC staff concludes that the instrument setpoint methodology meets the guidance inRIS 2006-17 and RG 1.105."SPECIFIC RAI RESPONSES:NRC Question 1Withdrawn.E-1 NRC Question 2In TS section 3.3.1, "RTS [Reactor Trip System] Instrumentation", Over-temperature delta-T,Surveillance Requirement SR 3.3.1.3, Note 2, the rated thermal power within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> of whichthe surveillance is to be performed was changed from >15% RTP to >25% RTP.Provide a justification for this change including where in the FSAR or the Supplemental SafetyEvaluation Report (SSER) it is addressed.Also, provide a summary of the calculation for this change and a description of the methodologyused to make the calculation.TVA ResponseThe value was changed from 15 percent to 25 percent because of the use of the WINCISEsystem described in detail in FSAR Section 7.2.1. The use of 25 percent Rated Thermal Powerwas approved by NRC in SSER 24. This is not an allowable or limiting value. It is a value thatis selected to ensure that the surveillance is performed at an appropriate reactor power level.Typically, the reactor would be above 50 percent power when the 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> timeframe is reached.It is also described in the associated TS Bases section on page B3.3-54. Because this is not acalculated value, there is no methodology associated with it.NRC Question 3In TS section 3.3. 1, "RTS Instrumentation"' Functional Unit 5, "Source Range Neutron Flux", theAllowable Value (AV) was changed from less than or equal to (<-) 1.5 E5 (counts per second(cps) to -1.33 E5 cps.Provide a justification for this change including where in the FSAR or the SSER it is addressed.Also, provide a summary of the calculations used for determining the A V, Nominal Trip Setpoint(NTSP), Total Loop Uncertainty, As-Found and As-Left Tolerances, as applicable, and adescription of the methodology used to make the calculationsTVA ResponseThe change to the Source Range Neutron Monitor Allowable Value was made to calculate thevalue in accordance with TSTF-493. Westinghouse does not specify Analytical Limits for theseinstrument loops. The allowable value was calculated in Setpoint and Scaling calculation2-NMD-92-131 based on the methodology provided in TVA EEB-TI-28. This TI was provided tothe NRC in Reference 4. The general FSAR discussion of setpoint methodology is provided inFSAR Section 7.1. NRC's review of the TVA Setpoint Methodology for the RTS is contained inSSER 23. NRC concluded that the methodology meets the relevant requirements of theStandard Review Plan (SRP) and is therefore acceptable. WBN Unit 1 has not updated toTSTF-493 methods and this is the reason for the differences. The specific TS values are notdiscussed in the FSAR, the TS Bases, or in an SSER.E-2 NRC Question 4In TS section 3.3.1, "RTS Instrumentation", Functional Unit 11, "Undervoltage RCPs [ReactorCoolant Pumps]", the A V was changed from 'a 4734 V to >- 5112 V, and the NTSP changed from4830 V to 5400 V.Provide a justification for these changes including where in the FSAR or the SSER they areaddressed.Provide a summary of the calculations used for determining the A V, NTSP, Total LoopUncertainty, As-Found and As-Left Tolerances, as applicable, and a description of themethodology used to make the calculations.TVA ResponseThe changes to the Undervoltage Reactor Coolant Pump TS values were made to calculate theNormal Measurable Accuracies and Allowable Values in accordance with TSTF-493. Theallowable value and nominal trip setpoint were calculated in Setpoint and Scaling calculationWBPE0689009007 based on the methodology provided in TVA EEB-TI-28. This TI wasprovided to the NRC in Reference 4. The general FSAR discussion of setpoint methodology isprovided in FSAR Section 7.1. NRC's review of the TVA Setpoint Methodology for the RTS iscontained in SSER 23. NRC concluded that the methodology meets the relevant requirementsof the SRP and is therefore acceptable. WBN Unit 1 has not updated to TSTF-493 methodsand this is the reason for the differences. These values are discussed in the TS Bases on pageB 3.3-23. The specific T/S values are not discussed in either the FSAR or in an SSER.NRC Question 5In TS section 3.3. 1, "RTS Instrumentation". Functional Unit 14.a, "Turbine Trip, Low Fluid OilPressure"; SR 3.3.1.18 was changed to SR 3.3.1.10.Provide a justification for this change including where in the FSAR or the SSER it is addressed.TVA ResponseThe surveillance requirement (SR) for the Turbine Trip, Low Fluid Oil Pressure was changedfrom 3.3.1.18 to 3.3.1.10 because 18 was a typographical error. No discussion in the FSAR orin an SSER is needed.E-3 NRC Question 6In TS section 3.3. 1, "RTS Instrumentation", Functional unit 14.a, "Turbine Trip, Low Fluid OilPressure"' the AV was changed from >_ 43 psig to > 38.3 psig.Provide a justification for these changes including where in the FSAR or the SSER they areaddressed.Also, provide summary calculations used for determining the A V, NTSP, Total Loop Uncertainty,As-Found and As-Left Tolerances, as applicable, and a description of the methodology used tomake the calculations.TVA ResponseThe change to the Turbine Trip, Low Fluid Oil Pressure allowable value was made to calculatethe value in accordance with the requirements of TSTF-493. There are no Analytical or SafetyLimits. The allowable value was calculated in Setpoint and Scaling calculation 2-PS-047-0073based on the methodology provided in TVA EEB-TI-28. This TI was provided to the NRC inReference 4. The general FSAR discussion of setpoint methodology is provided in FSARSection 7.1. NRC's review of the TVA Setpoint Methodology for the RTS is contained in SSER23. NRC concluded that the methodology meets the relevant requirements of the SRP and istherefore acceptable. WBN Unit 1 has not updated to TSTF-493 methods and this is the reasonfor the differences. The specific TS values are not discussed in the FSAR, the TS Bases, or inan SSER.NRC Question 7In TS section 3.3.2, "ESFAS [Engineered Safety Feature Actuation System] Instrumentation",SR 3.3.2.5, and in TS section 3.3.6 "Containment Vent Isolation Instrumentation", surveillancerequirement SR 3.3.6.5; the following note was added to the 18 month frequency:"and Potter & Brumfield MDR [motor-driven rotary] Series relays."The proposed changes would extend the test frequency of the Potter & Brumfield MDR Seriesrelays to 18 months. The applicant has also proposed adding the same changes to therespective TS Bases.The current WBN Unit 1 TS only identifies the Westinghouse Type AR relay as having asurveillance frequency of 18 months.By letter dated December 30 1998, the NRC issued Amendment No. 17 to Facility OperatingLicense No. NPF-90 for Watts Bar Nuclear Plant, Unit 1. The amendment was in response toTVA's license amendment application dated February 28, 1996, as supplemented October 2and December 12, 1997, March 30 and December 11, 1998. The February 28, 1996, letterproposed to extend the surveillance interval for Westinghouse type AR relays with alternatingcurrent and direct current coils from quarterly to an 18 month interval. The letter ofDecember 11, 1998 revised the scope of the application such that it applies only toWestinghouse type AR relays which use alternating current (ac) coils.E-4 Based on the review of WCAP- 13877, Rev. 1, WCAP- 13900, Rev. 0, and the licensee'ssubmittals referencing these topical reports, the NRC staff concluded that the proposed testinterval extension to 18 months for Westinghouse Type AR relays with ac coils used in ESFASslave relays applications was justified for WBN Unit 1.Only Westinghouse Type AR relays with ac coils are within the scope of WCAP- 13877.Potter & Brumfield MDR Series relays are not within the scope WCAP- 13877 (Rev. 1 or Rev. 2)and the conclusions of Amendment 17 are not applicable to Potter & Brumfield MDR relays.TR, WCAP- 13878, however, addresses the surveillance extension of Potter & Brumfield MDRrelays. Licensees that use Potter and Brumfield MDR relays for ESFAS subgroup relayapplications and are proposing test interval extensions based on WCAP- 13878 should:1. Confirm the applicability of the WCAP-13878, Rev. I analyses for their plant.2. Ensure that their procurement program for Potter & Brumfield MDR relays is adequate fordetecting the types of failures that are discussed in References 9, 10, 11, and 12 of theSER.3. Ensure that all pre- 1992 Potter & Brumfield MDR relays which are used in either normallyenergized or a 20 percent duty cycle, have been removed from ESFAS applications.4. Ensure that the contact loading analysis for Potter & Brumfield MDR relays has beenperformed to determine the acceptability of these relays.The NRC staff has not identified a previous NRC staff Safety Evaluation approving thesurveillance extension of Potter and Brumfield MDR relays for WBN or a License AmendmentRequest from TVA requesting such an extension for WBN based on WCAP- 13878.Provide a justification for extending the test frequency of the Potter & Brumfield MDR Seriesrelays to 18 months.TVA ResponseThe NRC correctly notes that Unit 1 uses Westinghouse Type AR slave relays while Unit 2 usesPotter & Brumfield MDR Series relays in addition to the Type AR relays. TVA has responded onseveral occasions to NRC questions with respect to WBN Unit 2's use of Potter & BrumfieldMDR relays. In each response, TVA has stated that the basis for an 18 month surveillanceinterval is WCAP-13878 R2 and NRC's acceptance of the WCAP. References 2 and 3 providedTVA's previous responses. SSER 23 identifies that Unit 2 will be using the Potter & BrumfieldMDR relays and that their use is acceptable. SSER 23 was issued eight months after TVA'sReference 2 RAI response stating that the surveillance interval was based on WCAP-13878 R2.TVA also notes that TS Bases SR 3.3.2.5 was updated to show the use of Potter & BrumfieldMDR relays and that the surveillance interval was based on the reliability assessment of WCAP-13878 R2. This revision of the TS Bases was submitted to the NRC on February 2, 2010.The justification for the use of an 18 month surveillance interval is provided in the followingdiscussion. TVA confirms that WCAP-13878, Rev. 2 is applicable to WBN Unit 2. Theconditions specified in the WCAP are met as shown in the following responses.1. Procurement of commercial parts for safety-related applications is done in accordancewith TVA procedure NEDP-8, "Technical Evaluation For Procurement of Materials andServices," Revision 21. The procedure requires that the Procurement Engineering Group(PEG) include testing requirements for the procurement of commercial items to be used inE-5 safety-related applications as part of the procurement specification. Further itrecommends that such testing be done by a third party instead of TVA.A review of the TVA stock numbers (CATIDs) for safety-related Potter & Brumfield MDRrelays found the following:a. The only CATIDs referenced for use in the solid-state protection system (SSPS)specify Westinghouse as the supplier. The use of Westinghouse to providethese relays is one of the SER approved methods for ensuring that the types offailures that are discussed in References 9, 10, 11, and 12 of the SER aredetected and such relays are not installed.b. While not specified for use in SSPS, the only other CATIDs for safety-relatedPotter & Brumfield MDR relays require procurement from the original equipmentsupplier under their Appendix B program or from Southern Testing Services (anapproved qualifier) using a previously approved testing program in accordancewith the requirements of NEDP-8. These methods are sufficient for ensuringthat the types of failures that are discussed in References 9, 10, 11, and 12 ofthe SER are detected and such relays are not installed in other safety-relatedapplications at WBN.2. No Potter & Brumfield MDR relays were supplied with the original WBN Unit 2 SSPSoutput cabinets. All Potter & Brumfield relays installed by Westinghouse during the 2010SSPS refurbishment were manufactured after 1992.The only other use of Potter & Brumfield MDR relays in SSPS is in the Safeguards TestCabinets. These relays were replaced as part of the Westinghouse 2010 SSPSrefurbishment.WBN Unit 2 contact loading analysis and the acceptability of installing MDR relays inspecific locations is documented in calculation WBNEEBIDQOO209920100002, "SSPSESFAS Slave Relay Contact Loading -Unit 2," Revision 0. The calculation was includedas part of the work order during the refurbishment of the SSPS cabinets to ensure that thecorrect type of relay was installed in each location.A review of the work orders and as-built inspection of the SSPS relay output cabinetsconfirmed that the MDR relays were installed in accordance withWBNEEBIDQOO209920100002 and no Potter & Brumfield MDR relays were installed in aprohibited location.3. Calculation WBNEEBIDQ00209920100001, Rev. 0 "SSPS ESFAS Slave & InterposingRelay Service Life Determination -Unit 2" confirmed that the Potter & Brumfield MDR styleAC relays used to actuate Unit 2 ESFAS functions exist in an environment that meets theenvironmental standards that were stipulated in WCAP- 13878.WCAP-13878 and the NRC concluded that Potter & Brumfield MDR ESFAS relays thatmeet the requirements stated in the WCAP can justifiably extend their surveillance testinterval from a 3 month interval to a refueling interval. Based on the conclusions ofcalculation WBNEEBIDQ00209920100001, the WBN 18 month surveillance interval isappropriate.E-6 In addition, in Reference 2, TVA committed to revise applicable attachments of TI-1 19,"Maintenance Rule Performance Indicator Monitoring, Trending, and Reporting," prior toimplementation of the approved Unit 2 TS. This procedure change will require that thesurveillance interval be evaluated and reduced, when needed, if two or morePotter & Brumfield MDR series relays used for Unit 2 TS LCOs 3.3.2 and 3.3.6 fail withina 12-month interval. Appropriate wording is already provided in TI-1 19 for the Type ARrelays. TVA believes that this commitment is appropriate for an inspector confirmatoryitem as opposed to an SSER open item.NRC Question 8In TS section 3.3.2, "ESFAS Instrumentation", SR 3.3.2.8; the following words were added atthe end of the surveillance note:"for manual initiation"The note now reads: "Verification of setpoint not required for manual initiation."Provide a justification for this change including where in the FSAR or the SSER it is addressed.TVA ResponseThis note was changed to match the wording for SR 3.3.2.8 in TSTF-493, Rev. 4. No setpoint isrequired or specified for this manual action. Manual action for these functions is taken if therequired automatic response did not occur. This is specified in plant operating procedure E-O,"Reactor Trip or Safety Injection."NRC Question 9In TS section 3.3.2, "ESFAS Instrumentation", Functional Unit 6.d, 'Auxiliary Feedwater, Loss ofOffsite Power", the following note was added to the surveillance requirement:"Notes (b) and (c) are applicable to SR 3.3.5.2 for this function."Provide a justification for this change including where in the FSAR or the SSER it is addressed.TVA ResponseThe notes added to the TS Section 3.3.2 Table with respect to Auxiliary Feedwater areconsistent with the Westinghouse Standard TS and TSTF-493 R4 Option A. The notes areconsistent with the Westinghouse Setpoint Methodology and the descriptions in FSARSection 7.1.2. They also comply with the positions noted by the NRC in Regulatory IssueSummary (RIS) 2006-17. SSER 23 provides NRC acceptance of the setpoint methodology forWBN Unit 2 including that it meets RIS 2006-17.E-7 NRC Question 10In TS section 3.3.2, "ESFAS Instrumentation", Functional unit 6.e, "Auxiliary Feedwater, Trip ofall Turbine Driven Main Feedwater Pumps" the A V was changed from > 48 psig to > 43.3 psig.Provide a justification for this change including where in the FSAR or the SSER it is addressed.Also, provide summary calculations used for determining the AV, NTSP, Total Loop Uncertainty,As-Found and As-Left Tolerances, as applicable, and a description of the methodology used tomake the calculations.TVA ResponseThe change to the Auxiliary Feedwater Trip of all Turbine Driven Main Feedwater PumpsAllowable Value was made to calculate the value in accordance with the requirements ofTSTF-493. These instruments are not safety-related and thus have no Safety or AnalyticalLimits. The allowable value was calculated in Setpoint and Scaling calculation 2-PS-046-13and -40 based on the methodology provided in TVA EEB-TI-28. This TI was provided to theNRC in Reference 4. The general FSAR discussion of setpoint methodology is provided inFSAR Section 7.1. NRC's review of the TVA Setpoint Methodology for the RTS is contained inSSER 23. NRC concluded that the methodology meets the relevant requirements of the SRPand is therefore acceptable. WBN Unit 1 has not updated to TSTF-493 methods and this is thereason for the differences. The specific TS values are not discussed in the FSAR, the TSBases, or in an SSER.E-8