ML072060666

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Analysis of EDO Response to ACRS Letter on Proposed NRC Staff and Industry Activities for Addressing Dissimilar Metal Weld Issues Resulting from the Wolf Creek Pressurizer Weld Inspection Results
ML072060666
Person / Time
Site: Wolf Creek Wolf Creek Nuclear Operating Corporation icon.png
Issue date: 04/26/2007
From: Hammer C
Advisory Committee on Reactor Safeguards
To: Shack W
Advisory Committee on Reactor Safeguards
Hammer C G
References
GT 210
Download: ML072060666 (1)


Text

April 26, 2007MEMORANDUM TO:William J. Shack, Acting ChairMaterials, Metallurgy, and Reactor Fuels SubcommitteeFROM:Charles G. Hammer, Senior Staff Engineer /RA/

SUBJECT:

ANALYSIS OF EDO RESPONSE TO ACRS LETTER ON PROPOSEDNRC STAFF AND INDUSTRY ACTIVITIES FOR ADDRESSINGDISSIMILAR METAL WELD ISSUES RESULTING FROM THE WOLFCREEK PRESSURIZER WELD INSPECTION RESULTSAttached is a copy of the EDO's April 23, 2007 letter of response to the ACRS' March 22, 2007letter on the proposed NRC staff and industry activities for addressing dissimilar metal weldissues resulting from the Wolf Creek pressurizer weld inspection results. A copy of theCommittee's letter is also attached.Committee LetterIn its March 22, 2007 letter the ACRS supported the agreement reached between the staff andthe industry on the resolution of dissimilar metal weld issues on pressurizer nozzles. The ACRSletter also stated that in the upcoming outages, the staff should encourage the industry toinspect all inspectable dissimilar metal welds on pressurizer nozzles before performingmitigation activities.

EDO ResponseThe EDO response stated that the advanced finite element analysis efforts being performed byboth the industry and staff are ongoing. The staff anticipates reaching conclusions by August2007 on whether these efforts would provide reasonable assurance of detectable leakage wellbefore rupture. The staff committed to keep the Committee informed of this issue as theseanalyses proceed. The EDO response also stated that there are a small number of plants that are inspecting thepressurizer nozzle welds prior to mitigation activities. The NRC regulations do not requireutilities to perform volume tric inspections prior to mitigation. However, the staff recognizes thevalue of inspecting these welds and have consistently encouraged utilities to perform pre-mitigation inspections where it is permitted.AnalysisThe EDO's response is satisfactory.

Attachments:As stated cc:ACRS MembersF. GillespieS. Duraiswamy C. Santos