ML073250003

Memo to Thomas G. Hiltz Key Issues for Discussion for November 28, 2007 Meeting on Steam Generator Tube Inspection License Amendment (Tac MD0197)

ML073250003
Person / Time
Site:	Wolf Creek
Issue date:	11/21/2007
From:	Donohew J N NRC/NRR/ADRO/DORL/LPLIV
To:	Hiltz T G NRC/NRR/ADRO/DORL/LPLIV
Donohew J N, NRR/DORL/LPL4, 415-1307
References
TAC MD0197
Download: ML073250003 (3)

Text

November 21, 2007MEMORANDUM TO:Thomas G. Hiltz, ChiefPlant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationFROM:Jack N. Donohew, Senior Project Manager/RA/Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

SUBJECT:

WOLF CREEK GENERATING STATION - KEY ISSUES FORDISCUSSION FOR NOVEMBER 28, 2007, MEETING ON STEAM GENERATOR TUBE INSPECTION LICENSE AMENDMENT (TAC NO. MD0197)Enclosed are six key issues to be addressed by Wolf Creek Nuclear Operating Corporation atthe scheduled meeting next week on November 28, 2007. These issues were sent to the licensee by email on November 20, 2007, so that the licensee would be able to discuss the issues in the meeting.These issues are based on the staff's review of the licensee's application dated February 21,2006, as supplemented by letters dated May 3 and September 27, 2007 (Agencywide Documents Access and Management System Accession Nos. ML060600456, ML071290104, and ML072750610, respectively).Docket No. 50-482 Enclosure

ML073250003OFFICENRR/LPL4/PMNRR/LPL4/LANRR/LPL4/BCNAMEJDonohewJBurkhardtThiltz, JND for DATE11/21/0711/21/0711/21/07 MEETING AGENDA - KEY ISSUES FOR DISCUSSIONMEETING OF NOVEMBER 28, 2007, FOR TAC NO. MD0197WOLF CREEK GENERATING STATION1.The staff wishes to discuss the conservatism of the crevice pressures used in theH*analyses. The use of the "limiting median crevice pressure approach" (see Appendix C of latest RAI response) seems to the staff to only be conservative for the upper region of the H* region and to be potentially non-conservative in the lower region of the H*

which is where most of the axial force on the tube must be reacted. The staff would like to understand why the use of an elevation-dependant crevice pressure based directly on the White Paper test results (i.e., Appendix C) is not needed to ensure a conservative analysis.2.The staff wishes to discuss the conservatism of the assumed residual pullout resistanceof [proprietary value] associated with the hydraulic expansion process with respect tothe minimum residual pullout strength which may be exhibited among the 21,500 tubesin the Wolf Creek steam generators. 3.Depending on the result of the discussions on issues 1 and 2 above, the staff may liketo discuss whether or not these issues can be mitigated by taking actions (e.g., divider plate weld inspections) to ensure that the divider plate will remain intact. 4.The staff wishes to discuss its continuing concern about the potential for progressive,incremental slippage of the tubes within the tubesheet under normal operating conditions (see most recent RAI questions 8 and 9) and the need to monitor the tubing to ensure that such slippage is not taking place. 5.The tubesheet zones shown in Figure 11-4 in Attachment C do not appear to beconsistent with those in the table entitled, "Steam Generator Tube Inspection Depths" for the cold leg in the proposed technical specification amendment. The licensee is requested to explain this apparent inconsistency and whether any corrections are

needed.6.It would be helpful to the staff if tables and figures comparable to those in Appendix Ccould be provided at the meeting for the case of a fully intact divider plate to tubesheet weld (i.e., divider plate factor equal to 0.399).