ML061810503

Browns Ferry Ltr - Request for Additional Information Re ASME, Section Xi, ISI Program Submittal of Third 10-Year Inspection Interval Program Relief Request No. 3-ISI-21

ML061810503
Person / Time
Site:	Browns Ferry
Issue date:	09/15/2006
From:	Brown E A NRC/NRR/ADRO/DORL/LPLII-2
To:	Singer K E Tennessee Valley Authority
Brown, E, NRR/DORL, 415-2315
References
TAC MC8795
Download: ML061810503 (3)

Text

September 15, 2006Mr. Karl E. SingerChief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801

SUBJECT:

BROWNS FERRY NUCLEAR PLANT, UNIT 3 - REQUEST FOR ADDITIONALINFORMATION REGARDING AMERICAN SOCIETY OF MECHANICAL ENGINEERS SECTION XI, INSERVICE INSPECTION PROGRAM SUBMITTAL OF THIRD 10-YEAR INSPECTION INTERVAL PROGRAM - RELIEF REQUEST NO. 3-ISI-21 (TAC NO. MC8795)

Dear Mr. Singer:

By letter to the Nuclear Regulatory Commission (NRC) dated October 19, 2005, the TennesseeValley Authority (TVA) submitted Relief Request 3-ISI-21 for Browns Ferry Nuclear Plant, Unit 3 from the inservice inspection requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code. TVA proposes to adopt risk-informed selection of piping welds for examination.Based on our review of TVA's submittal, the NRC staff finds that a response to the enclosedrequest for additional information is needed before we can complete the review.This request was discussed with TVA staff on July 10, 2006, and it was agreed that a responsewould be provided within 30 days from the issuance of this letter.If you have any questions, please contact me at (301) 415-2315.Sincerely,/RA/Eva A. Brown, Project ManagerPlant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket No. 50-296

Enclosure:

Request for Additional Information cc w/encl: See next page

ML061810503 OFFICELPL2-2/PMLPL2-2/PMLPL2-2/LACPNB/BCAPLB/BCLPL2-2/BCNAMELRegnerEBrownBClaytonTChan by memo datedLMrowca LRaghavanDATE 9 /14 /069/15/069/14/06 6/19/06 9 /14/069/15/06 EnclosureREQUEST FOR ADDITIONAL INFORMATIONRISK-INFORMED INSERVICE INSPECTION RELIEF REQUESTTHIRD 10-YEAR INSERVICE INSPECTION PROGRAM RELIEF REQUEST 3-ISI-21TENNESSEE VALLEY AUTHORITYBROWNS FERRY NUCLEAR PLANT, UNIT 3 DOCKET NO. 50-2961.On pages 31 and 32 of Relief Request (RR) 3-ISI-21 dated October 19, 2005,Section 7.0 Parts (1) and (2) contains the following:Note: Class 1 (Class 2) piping welds shall be in accordance withthe RI-ISI [risk-informed inservice inspection] additional examination requirements of [American Society of Mechanical Engineers (ASME)] Code Case N-577, as outlined in Section 7.12 of this program. Section 7.12.5.4.J. states: "An evaluation shall be performed to establish when thoseexaminations are to be conducted." Use of an evaluation to determine when a second sample expansion is to be performed is inconsistent with regulations. If flaws or relevant conditions are identified, sample expansions are to occur during the current outage in accordance with ASME Boiler and Pressure Vessel Code,Section XI, Subsection IWB-2430(b). The licensee needs to address the time frame in which sample expansions will be performed. 2.Of the items selected for RI-ISI listed in the table included in Attachment 1, state howmany are socket welds. Provide a breakdown of the examination technique to be performed on the items selected for examination, include the frequency of examination.3.Page 61, Section 7.12.4, references Part 6 of Table R-A and 3-SI-4.6.G-A. Thesereferences are not provided. The licensee also lists ASME Code Case N-577 as part of the guidance used to develop its RI-ISI program. The staff has not endorsed the use of Code Case N-577. The licensee needs to provide the references or explain the licensee's Risk-Informed Process. The references or explanation needs to include how the program was developed, using what guidance, and explain any deviations from the referenced guidance. 4.Page 64 addresses the Corrective Action Program. The licensee states that "For CodePiping categorized as High Safety Significance (HSS) the corrective action shall be consistent with the provision of ASME Code Section XI." Describe what corrective action measures will be used for Low Safety Significant (LSS) Code piping.

5.Define the smallest diameter pipe included in the scope of the RI-ISI program forClass 1 and 2 piping. Specify whether the scope included all Class 1 and 2 piping or if there was a defined minimum diameter. Provide justification for the defined scope.6.Attachment 1 to RR 3-ISI-1 indicates that the number of inspections was reduced from100 in the second interval to 71 proposed for the third interval. Notable are reductions in examinations of Category A intergranular stress-corrosion cracking (IGSCC) susceptible piping associated with the reactor recirculation, reactor water cleanup, and core spray systems, as well as of Category C IGSCC-susceptible piping associated withthe core spray system.Tennessee Valley Authority (TVA) states on page 190 that "deletions from the previousprogram are entirely attributable to lower failure rates due to the implementation of the hydrogen water chemistry/noble metal injection program, with the corresponding impact on IGSCC."Provide a description of TVA's methodology and an explanation of how the estimatedreduction in the failure rates propagated through the methodology result in the significant reduction in the number of inspections for the third 10-year interval. The explanation should address the following specific questions the staff has developed based on the information provided in the submittal.A.Explain precisely how TVA was able to justify the deletion of each of thediscontinued inspections in its proposed RI-ISI program for the third interval. For those welds in segments recategorized from HSS to LSS, data for both the previous program and the proposed program, similar to that provided in of TVA's response to Requests for Additional Information dated January 18, 2000, is suggested. For deleted welds in segments still consideredHSS, data in the format of Table 3.8-1 of TVA's original submittal is suggested.

Also, add to this table the previous and proposed failure rate, core damage frequency (CDF), and risk reduction worth data for each of these welds. If certain welds with a previous "quantified failure rate" now have a "zero failure rate," provide documentation to demonstrate that the traditional ASME Section XI criteria are being met.B.It was observed that, despite the net reduction of proposed inspections, therewere a few added inspections (e.g., two new intergranular stress-corrosion cracking Category C locations in the reactor recirculation system). Explain thereason for these additions.

7. Given the numerous changes to TVA's PRA, describe in more detail the process used toevaluate the impact of these changes on the current risk-ranking of BFN3's pipe segments. As part of the description, indicate whether or not the conditional core damage probability (CCDPs) of the segments with the current PRA model wererecalculated.If TVA did perform a recalculation, provide the date, revision number, base CDF andLERF of the PRA model used for redetermining CCDPs, CDFs, or conditional CDF ofthe pipe segments.If TVA did not perform a recalculation, explain why the changes made to the PRA inconnection with the Facts and Observations and PER item resolutions of August 2003 do not impact the risk-ranking of BFN3's pipe segments.

8.Since a peer review has not been conducted, provide the following information:

A.A description of the review processes TVA employed in conjunction with theupgrades to the PRA models. Along with this, describe the level of expertise of the reviewers.B.An evaluation of the impact of the non-EPU related modeling errors specificallynoted in Section 3.8 of the audit report (also documented in the BFN3 Corrective Action Program as Problem Evaluation Report (PER) No. 96035) on the RI-ISI application. In other words, if these errors are corrected, what impact will this have on the relative importance of BFN3's pipe segments?

Mr. Karl W. SingerBROWNS FERRY NUCLEAR PLANTTennessee Valley Authority cc:

Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice PresidentNuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Brian O'Grady, Site Vice PresidentBrowns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Robert J. Beecken, Vice PresidentNuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 General CounselTennessee Valley Authority ET 11A 400 West Summit Hill DriveKnoxville, TN 37902Mr. John C. Fornicola, ManagerNuclear Assurance and Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Mr. Bruce Aukland, Plant ManagerBrowns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Robert G. Jones, General ManagerBrowns Ferry Site Operations Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Mr. Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801Mr. William D. Crouch, M anagerLicensing and Industry Affairs Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609Senior Resident InspectorU.S. Nuclear Regulatory Commission Browns Ferry Nuclear Plant 10833 Shaw Road Athens, AL 35611-6970State Health OfficerAlabama Dept. of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, AL 36130-3017ChairmanLimestone County Commission 310 West Washington Street Athens, AL 35611