ML13318A011

Comanche Peak - Response to Request for Additional Information Regarding Closure Options for Generic Safety Issue 191

ML13318A011
Person / Time
Site:	Comanche Peak
Issue date:	10/31/2013
From:	Flores R, McCool T P Luminant Generation Co, Luminant Power
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CP-201301214, GL 2004-02, GSI-191, TAC MC4676, TAC MC4677, TXX-13149
Download: ML13318A011 (4)

Text

Rafael FloresSenior Vice President& Chief Nuclear Officerrafael.flores@Luminant.comLuminant PowerP 0 Box 10026322 North FM 56Glen Rose, TX 76043LuminantT 254 897 5590C 817 559 0403F 254 897 6652REF: GL 2004-02CP-201301214TXX-13149October 31, 2013U. S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555-0001SUBJECT: COMANCHE PEAK NUCLEAR POWER PLANT (CPNPP)DOCKET NOS. 50-445 AND 50-446RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDINGCLOSURE OPTIONS FOR GENERIC SAFETY ISSUE 191(TAC NOS. MC4676 AND MC4677)REFERENCE: 1.Letter logged TXX-13091, dated May 16, 2013, from Rafael Flores of LuminantPower to Balwant Singal of the NRC, RE: Closure OPTIONS FOR GENERICSAFETY ISSUE 191 (GSI-191), ASSESSMENT OF DEBRIS ACCUMULATION ONPRESSURIZED WATER REACTOR SUMP PERFORMANCE, (ML 13149A101)2. Letter dated September 30, 2013, from Balwant Singal of the NRC to Rafael Flores ofLuminant Power, RE: Comanche Peak Nuclear Power Plant, Units I and 2 -Requestfor Additional Information Regarding Closure Options for Generic Safety Issue 191,ASSESSMENT OF DEBRIS ACCUMULATION ON PRESSURIZED-WATERREACTOR SUMP PERFORMANCE (ML 13267A197)Dear Sir or Madam:In Reference 1, Luminant Generation Company LLC (Luminant Power) provided the U.S. NuclearRegulatory Commission (NRC) staff with the intended path forward for the resolution of Generic SafetyIssue (GSI)-191, "Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance,"for Comanche Peak Nuclear Power Plant, Units 1 and 2 (CPNPP). Luminant Power identified thatCPNPP will follow Option 2a (defined as deterministic approach with additional modeling refinementsin SECY-12-0093).A member of the STARS AllianceCallaway

• Comanche Peak

• Diablo Canyon -Palo Verde

• South Texas Project

• Wolf CreekAdD U. S. Nuctear Regulatory CommissionTXX-13149Page 2 of 210/31/2013In Reference 2, the NRC staff requested the following additional information to complete the review ofLuminant Power's path forward for the resolution of GSI-191 for CPNPP:1. Please provide the Westinghouse recommended mitigative measures deemed necessary for CPNPP,and if not yet implemented, the schedule for implementing the Westinghouse recommendations.2. Please provide the details of actions performed by EOPs FRC-0-1A, FRC-0.1B, FRC-0.2A, andFRC-0.2B to deal with inadequate core cooling.The attachment to this letter provides the requested information.This communication contains no new commitments regarding CPNPP Units 1 and 2.Should you have any questions, please contact Mr. J. D. Seawright at (254) 897-0140.I state under penalty of perjury that the foregoing is true and correct.Executed on October 31, 2013.Sincerely,Luminant Generation Company LLCRafael FloresBy:Thomas P. McCoolVice President, Station SupportAttachmentc -Marc L. Dapas, Region IVBalwant K. Singal, NRRResident Inspectors, Comanche Peak

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to TXX-13149Page 1 of 2NRC Request No. 1.Please provide the Westinghouse recommended mitigative measures deemed necessary for CPNPP,and if not yet implemented, the schedule for implementing the Westinghouse recommendations.CPNPP Response:Westinghouse and the PWR Owners Group recommended (Ref. Direct Work Requests DW-01-017dated 02/20/2008 and DW-12-13 dated 03/20/2013) that the following changes be made to genericEmergency Operating Procedures.* ES-1.3, Loss of Reactor or Secondary Coolant (CPNPP EOS-1.3A for Unit 1 and CPNPP EOS-1.3B for Unit 2)Westinghouse recommended that the following be added to the PLANT-SPECIFICINFORMATION section of the Step Description Table for Step 6 (Step 7 LP) of ES-1.3:"Some plants may be susceptible to blockage in the fuel assemblies due to debris passingthrough the sump screen. Plants can assess the impact of debris on equipment required by theECCS and NSSS to maintain the core in a coolable geometry following an accident usingWCAP-16406-P, Rev. 1, "Evaluation of Downstream Sump Debris Effects in Support of GSI-191". Susceptible plants should evaluate the use of available temperature monitoring (core exitthermocouples or PAMS) to initiate backflow through the core via hot leg recirculation on apotentially more frequent basis to ensure adequate core cooling. An analysis may be needed todetermine the frequency of switching to and from hot-leg injection to satisfy core blockagerequirements while addressing boron precipitation concerns."The corresponding step in the CPNPP procedures (step 14) determines if transfer to hot legrecirculation will be required. The plant staff is consulted for this determination. In accordancewith the generic recommendation, this guidance was added to the Plant Staff Document for useby the Emergency Response Organization." FR.C.1 Response to Inadequate Core Cooling (CPNPP FRC-0-1A for Unit 1 and CPNPP FRC-0.1B for Unit 2) and FR.C.2 Response to Degrade Core Cooling (CPNPP FRC-0.2A for Unit 1and CPNPP FRC-0.2B for Unit 2)Westinghouse recommended that the following be added to the PLANT-SPECIFICINFORMATION section of the Step Description Table for Step 2 (HP and LP) of FR-C. 1 andStep 2 (HP and LP) of FR-C.2:"Some plants may be susceptible to blockage in the fuel assemblies due to debris passingthrough the sump screen. Plants can assess the impact of debris on equipment required by theECCS and NSSS to maintain the core in a coolable geometry following an accident usingWCAP-16406-P, Rev. 1, "Evaluation of Downstream Sump Debris Effects in Support of GSI-191". During the recovery, if SI flow is indicated and core cooling remains inadequate, SI flowmay not be reaching the core due to blockage. It may be possible to restore adequate corecooling by initiating backflow through the core via hot leg recirculation."These changes to CPNPP procedures have been implemented by incorporation into the bases for thecorresponding step in CPNPP procedures (step 3) and by changes to the Plant Staff Document for useby the Emergency Response Organization.

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to TXX-13149Page 2 of 2Westinghouse also recommended procedure changes for plants that use a Westinghouse-designedreactor vessel level indication system. These do not apply to the CPNPP Reactor Vessel Water LevelIndication System (RVLIS) design which employs heated and unheated junction thermocouples asdescribed in the CPNPP FSAR TMI RESPONSE TO NRC ACTION PLAN DEVELOPED AS A RESULTOF THE TMI-2 ACCIDENT,Section II.F.2 IDENTIFICATION OF AND RECOVERY FROMCONDITIONS LEADING TO INADEQUATE CORE COOLING.NRC Request No. 2.Please provide the details of actions performed by EOPs FRC-0-1A, FRC-0.1B, FRC-0.2A, and FRC-0.2Bto deal with inadequate core cooling.CPNPP Response:CPNPP FRC-0-1A for Unit 1 and CPNPP FRC-0.1B for Unit 2 are titled Response to Inadequate CoreCooling. This procedure is entered from Critical Safety Function CORE COOLING Status Tree whenCore Exit Temperature (CET) is greater than or equal to 1200 degrees F.CPNPP FRC-0.2A for Unit 1 and CPNPP FRC-0.2B for Unit 2 are titled Response to Degrade CoreCooling. This procedure is entered from Critical Safety Function CORE COOLING Status Tree whenRCS subcooling is inadequate, Reactor Vessel Water Level Indication System (RVLIS) indicates lowlevel in the vessel and Core Exit Temperature (CET) is greater than or equal to 750 degrees F.Both procedures are based on assuring emergency core cooling to the reactor vessel. None of the stepsin the original generic or plant specific guidance dealt with core blockage. There are no actions to betaken for core blockage other than switchover from cold leg recirculation to hot leg recirculation andback. Therefore, the guidance added is to contact the Plant Staff for specific guidance.The Shift Technical Advisors (STAs) and/or the Technical Support Center (TSC) engineers wouldmonitor plant conditions and advise the control room operators regarding switchover from Cold LegRecirculation to Hot Leg Recirculation and back.