ML11297A033

Cooper, Response to Nuclear Regulatory Commission Request for Additional Information for Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves

ML11297A033
Person / Time
Site:	Cooper
Issue date:	10/18/2011
From:	Willis D L Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2011088, TAC ME5287
Download: ML11297A033 (6)

Text

NNebraska Public Power DistrictAlways there when you need us50.90NLS2011088October 18, 2011U.S. Nuclear Regulatory CommissionAttention: Document Control DeskWashington, D.C. 20555-0001

Subject:

Response to Nuclear Regulatory Commission Request for Additional Informationfor Reducing the Number of Technical Specification 3.4.3 Required Safety ReliefValves (TAC No. ME5287)Cooper Nuclear Station, Docket No. 50-298, DPR-46

References:

1. Letter from Lynnea E. Wilkins, U. S. Nuclear Regulatory Commission, toBrian J. O'Grady, Nebraska Public Power District, dated June 3, 2011,"Cooper Nuclear Station -Request for Additional Information LicenseAmendment Request for Reducing the Number of Technical Specification3.4.3 Required Safety Relief Valves (TAC NO. ME5287)"2. Letter from Brian J. O'Grady, Nebraska Public Power District, to the U.S.Nuclear Regulatory Commission, dated January 5, 2011, "LicenseAmendment Request for Reducing the Number of Technical Specification3.4.3 Required Safety Relief Valves"3. Letter from Brian J. O'Grady, Nebraska Public Power District, to the U.S.Nuclear Regulatory Commission, dated October 6, 2011, "Supplement toLicense Amendment Request for Reducing the Number of TechnicalSpecification 3.4.3 Required Safety Relief Valves"

Dear Sir or Madam:

The purpose of this letter is for Nebraska Public Power District (NPPD) to submit a response to arequest for additional information (RAI) from the Nuclear Regulatory Commission (NRC)(Reference 1). The RAI requested information in support of NRC's review of a licenseamendment request (LAR) for the Cooper Nuclear Station (CNS) Technical Specifications (TS)to revise TS 3.4.3, "Safety/Relief Valves (SRVs) and Safety Valves (SVs)" to reduce the numberof SRVs required to be OPERABLE for over-pressure protection (Reference 2).Responses to the specific RAI questions were discussed in a public telephone conference on July12, 2011. Afterwards, the NRC requested these responses be submitted to the public docket, andthey are provided here in the Attachment with revisions as discussed. Subsequent to the publicCOOPER NUCLEAR STATION V 0oIP.O. Box 98 / Brownville, NE 68321-0098Telephone: (402) 825-3811 / Fax: (402) 825-5211ww-w.nppd .com NLS2011088Page 2 of 2teleconference, NPPD decided to supplement the LAR and request seven of eight rather than fiveof eight SRVs (Reference 3). No regulatory commitments are made in this submittal.The information submitted by this response to the RAI does not change the conclusions nor thebasis of the no significant hazards consideration evaluation provided with Reference 3.If you have any questions concerning this matter, please contact David Van Der Kamp,Licensing Manager, at (402) 825-2904.I declare under penalty of perjury that the foregoing is true and correct.Executed on (da /a IDI(dafe)Sincerely,Demetrius L. WillisGeneral Manager of Plant Operations/emAttachmentcc: Regional Administrator w/ attachmentUSNRC -Region IVCooper Project Manager w/ attachmentUSNRC -NRR Project Directorate IV- 1Senior Resident Inspector w/ attachmentUSNRC -CNSNebraska Health and Human Services w/ attachmentDepartment of Regulation and LicensureNPG Distribution w/o attachmentCNS Records w/ attachment NLS2011088AttachmentPage 1 of 3AttachmentResponse to Nuclear Regulatory Commission Request for Additional Informationfor Reducing the Number of Technical Specification 3.4.3 Required Safety Relief Valves(TAC No. ME5287)Cooper Nuclear Station, Docket No. 50-298, DPR-46Ouestion #1Please discuss if all cases were analyzed (i.e., all transients addressed).ResponseAs discussed in the public teleconference on July 12, 2011, the Safety Relief Valve (SRV)analysis was performed for the limiting cases of Transients and Special Events, i.e. mostbounding. Licensing-Basis for Over-Pressure Protection (OPP) identifies the limitingtransient to be Main Steam Isolation Valve (MSIV) fast closure followed by a high neutronflux scram. The limiting special event for OPP is the Anticipated Transient Without Scram(ATWS) with MSIV closure or pressure regulator fails open.Ouestion #2Please discuss the number of SR Vs that are needed for operation as described in the design basiscalculations.ResponseFive SRVs are needed for operation. The GE Hitachi Reports provided with Reference 1are now the Cooper Nuclear Station (CNS) design analysis for the required number ofSRVs.Ouestion #3Please discuss if these valves have caused a plant shutdown in the past.ResponseNo. SRV failures have not caused a plant shutdown.Ouestion #4Please discuss the timing and increments related to SR V actuation for the full range oftransients. Please also discuss which five will be the "required" valves or, if the request is foranyfive, justify the basis for the TS having only four SR Vs available when in the LimitingCondition for Operation.

NLS2011088AttachmentPage 2 of 3ResponseSafety Valves (SVs) and SRVs actuate over the full spectrum of transients as follows. SVsspring tension is set at 1240 + 37.2 psig and provides blowdown of approximately 38 to 50psig, and they relieve > 644,543 lbm/hr each.Spring lift setpoints for SRVs 71A, 71B and 71G are set at 1100 + 33.0 psig and havecapacity > 877,900 lbm/hr each. SRVs 71C, 71E and 71H are set at 1090 +/- 32.7 psig andhave capacity > 870,000 lbm/hr each. SRVs 71D and 71F are set at 1080 +/- 32.4 psig andhave capacity > 862,100 lbm/hr each.The request was not for specifically identified SRVs, but for any five OPERABLE. Afterthe July 12, 2011 public teleconference, Nebraska Public Power District (NPPD) decided tosupplement the submittal and request seven of eight SRVs required in TechnicalSpecifications (TS) Limiting Condition for Operation (LCO) 3.4.3 to be operable instead offive of eight. This will reserve two SRVs above the five required for OPP and ATWSwhen operating in a condition of one SRV inoperable as permitted by the LCO actionstatement.Ouestion #5Please discuss if human factors will affect the mitigation of an accident and, ifso, if a humanfactors analysis has been performed.ResponseHuman Factors are not affected, because TS LCO 3.4.3 only affects the SRV pilot actuatedspring lift function for OPP and ATWS. Manual actions are not required to mitigate OPPor ATWS consequences. No human factors analysis was required.Ouestion #6Please discuss if the maintenance rule was taken into consideration. What maintenance issues, ifany, contributed to the need for this request?ResponseMaintenance Rule Functional Failure (MRFF) Evaluations include two SRV functions:MS-Fl 1, Maintain Reactor Coolant Pressure Boundary, and ADS-PF02, Prevent.Overpressurization of the Nuclear System (Mechanical Components).For SRV MRFFs, CNS noted the following. An MRFF does not exist if the SRV canperform its Safety Related Function; the design functions of SRVs are not being changed.MRFF evaluations are performed for each failure, regardless of how many SRVs arerequired by TS. Since MR became effective, all SRV as-found bench test failures have NLS2011088AttachmentPage 3 of 3been evaluated for MRFF, and the only MRFF CNS has had was in 2003 when SRV 71 Gon Main Steam Line 'D' lifted in excess of its Analytical Limit.No maintenance issues contributed to the need for this request.Ouestion #7Please discuss how the reduction in required SR Vs affects the heat load in the suppression pool.ResponseSuppression Pool heat loads for SRV lifts are bounded by the CNS Loss of CoolantAccident analysis values.Ouestion #8Please discuss any structural issues that would be impacted.ResponseThe analysis shows that Suppression Pool and Drywell structural components remaincapable of coping with SRV lifts in response to the bounding events and transients.Ouestion #9For all the above, please discuss the basis for concluding the change would not increase theprobability/consequences of an accident and not reduce safety margins as described in theUpdated Safety Analysis Report.ResponseAfter the July 12, 2011 public teleconference, NPPD decided to supplement the submittaland request seven of eight SRVs required in TS LCO 3.4.3 to be OPERABLE instead offive of eight. The No Significant Hazards Consideration evaluation was revised andprovided in Reference 3. It provides the new basis for concluding the change would notincrease the probability/consequences of an accident and not reduce safety margins.

ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS©4ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS04Correspondence Number: NLS2011088The following table identifies those actions committed to by Nebraska Public Power District(NPPD) in this document. Any other actions discussed in the submittal represent intended orplanned actions by NPPD. They are described for information only and are not regulatorycommitments. Please notify the Licensing Manager at Cooper Nuclear Station of anyquestions regarding this document or any associated regulatory commitments.COMMITMENT COMMITTED DATECOMMITMENT NUMBER OR OUTAGENone4 4.4 4-4. 1-PROCEDURE 0.42 REVISION 27 PAGE 18 OF 25 [