ML11321A221
| ML11321A221 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/09/2011 |
| From: | Madden F W Luminant Generation Co, Luminant Power |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CP-201101565, TAC ME6789, TAC ME6790, TXX-11136 | |
| Download: ML11321A221 (4) | |
Text
aLuminantRafael FloresSenior Vice President& Chief Nuclear OfficerRafael.Flores@Luminant.comLuminant PowerP 0 Box 10026322 North FM 56Glen Rose, TX 76043T 254 897 5550C 817 559 0403F 254 897 6652CP-201101565Log # TXX-11136Ref. # 10CFR50.90November 9, 2011U. S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555SUBJECT: COMANCHE PEAK NUCLEAR POWER PLANT (CPNPP)DOCKET NOS. 50-445 AND 50-446RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION, RISK INFORMEDJUSTIFICATION FOR THE RELOCATION OF SPECIFIC SURVEILLANCE FREQUENCYREQUIREMENTS TO LICENSEE CONTROLLED PROGRAM -TACS ME6789 ANDME6790REFERENCES: 1. Letter logged TXX-11093 dated August 1, 2011 from Rafael Flores to the NRCsubmitting License Amendment Request (LAR)11-001, Application For TechnicalSpecification Change Regarding Risk-Informed Justification For The Relocation OfSpecific Surveillance Frequency Requirements To A Licensee Controlled Program.2. Letter logged TXX-11100 dated August 15, 2011 from Rafael Flores to the NRCsubmitting Supplement To License Amendment Request (LAR)11-001, "ApplicationFor Technical Specification Change Regarding Risk-Informed Justification For TheRelocation Of Specific Surveillance Frequency Requirements To A LicenseeControlled Program".3. Email dated October 26, 2011 from Balwant Singal of the NRC to Timothy Hope ofLuminant Power requesting additional information regarding License AmendmentRequest (LAR)11-001.Dear Sir or Madam:Per references 1 and 2, Luminant Generation Company LLC (Luminant Power) previously submittedLicense Amendment Request (LAR)11-001 requesting changes to the Comanche Peak Nuclear PowerPlant (CPNPP) Technical Specifications (TSs) for adoption of the Nuclear Regulatory Commission(NRC) approved Technical Specification Task Force (TSTF) -425, Revision 3, "Relocate SurveillanceFrequencies to Licensee Control -RITSTF [Risk-Informed TSTF] Initiative 5b." Per reference 3, theNRC provided a request for additional information regarding the subject license amendment request.Luminant Power has provided the information requested per reference 3 in the Attachment to thisletter.This communication contains no new commitments regarding Comanche Peak Units 1 and 2.Should you have any questions, please contact Mr. Rob Slough at (254) 897-5727.A member of the STARS (Strategic Teaming and Resource Sharing) AllianceCallaway
- Comanche Peak
- Diablo Canyon -Palo Verde
- San Onofre
- South Texas Project -Wolf Creek U. S. Nuclear Regulatory CommissionTXX-11136Page 2 of 2Sincerely,Luminant Generation Company LLCRafael FloresBy: KMirer WMaddehDirector, Oversight & Regulatory AffairsRASAttachment: Response To Request For Additional Information -Risk Informed JustificationFor The Relocation Of Specific Surveillance Frequency Requirements To LicenseeControlled Program -TACs ME6789 and ME6790c -E. E. Collins, Region IVB. K. Singal, NRRResident Inspectors, Comanche PeakMs. Alice RogersEnvironmental & Consumer Safety SectionTexas Department of State Health Services1100 West 49th StreetAustin, Texas 78756-3189
Attachment
to TXX-11136Page 1 of 2RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION -RISK INFORMED JUSTIFICATIONFOR THE RELOCATION OF SPECIFIC SURVEILLANCE FREQUENCY REQUIREMENTS TOLICENSEE CONTROLLED PROGRAM -TACS ME6789 AND ME6790The following questions were provided to Luminant Power in the email dated October 26, 2011 fromBalwant Singal of the NRC to Timothy Hope of Luminant Power (Reference 3) requesting additionalinformation regarding LAR 11-001:1. The summary of finding and observation (F&O) 2-13 for supporting requirement (SR) AS-A7identifies that the documentation of assumptions and key sources of uncertainty for accidentsequence modeling is incomplete, and two examples are provided by the peer reviewer. Thedisposition of this F&O was to specifically address these two examples, but there is no discussionof any review to identify other sources of uncertainty not documented. Since the peer reviewidentifies the two specific items as examples, the U. S. Nuclear Regulatory Commission's (NRC)staff would not expect the licensee to close out this F&O until a more thorough review wasconducted to assure all sources of uncertainty and assumptions are identified and discussed inthe documentation.Please discuss how this F&O was reviewed to determine the extent of condition for missingassumptions and key sources of uncertainty related to accident sequence modeling.2. The summary of F&O 4-31 for SR QU-F4 states that the effect of sources of uncertainty on theProbabilistic Risk Assessment (PRA) model is not clear. The resolution states that thedocumentation identifies the application of an industry guidance document to the evaluation ofuncertainties. This does not seem to address the underlying issue that the documentation shouldcharacterize sources of uncertainty and assumptions underlying the PRA model.Please clarify how this F&O was addressed to assure characterization of sources of uncertaintyand assumptions on the effects on the PRA model is described in the documentation.Luminant Power's Response to Question 1:F&O 2-13 included two proposed resolutions from the Peer Review team. The first proposedresolution dealt with the possible uncertainty from not including further development of offsitepower recovery sequences. The second proposed resolution dealt with potential uncertaintiesresulting from deviations in the incorporation of the WCAP-15831 ATWS model. The LARsubmittal described the incorporation of these proposed resolutions into the CPNPP PRA modeland/or model documentation. Both of these items were added to the list of potentialuncertainties in the respective PRA notebooks. The proposed resolutions were limited to the twospecific examples, and the performance of the uncertainty analysis (see RAI response #2) did notidentify any additional sources of uncertainty that would impact Accident Sequencedevelopment.Luminant Power's Response to Question 2:The proposed resolution to this F&O by the peer team was the following: Consider using theapproach recommended in the EPRI report 1016737, "Treatment of Parameter and ModelUncertainty for Probabilistic Risk Assessments," December 2008.The EPRI document identifies all sources of model uncertainty that are pertinent to a generalPRA model in meeting the SRs: QU-E1, QU-E2, QU-E4, QU-F4, and LE-F3. Table A-1 from thatdocument generically characterizes these sources. Per the peer review suggestion, the CPNPPPRA "Sensitivity and Uncertainty" notebook was updated to include this table (A-1) with the 4Attachment to TXX-11136Page 2 of 2identification of the plant-specific approach used for each case and where each source ofuncertainty can impact the model. The notebook (with its Level 2 reference) documents over 50sensitivity cases performed on the model involving the full range of the uncertainties identifiedin the table. The revised "Sensitivity and Uncertainty" notebook documents the characterizationof the sources of uncertainty and assumptions underlying the PRA model and resolves the PeerReview F&O.