ML20077K010

Responds to NRC Bulletin 89-001,Suppl 2, Failure of Westinghouse Steam Generator Tube Mechanical Plugs

ML20077K010
Person / Time
Site:	Wolf Creek
Issue date:	07/31/1991
From:	Rhodes F WOLF CREEK NUCLEAR OPERATING CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ET-91-0132, ET-91-132, IEB-89-001, IEB-89-1, NUDOCS 9108060143
Download: ML20077K010 (3)

Text

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i LFCREEK W@ NUCLEAR OPERATING COR forrest T. Rhodes vicw President Engineenng & Techrncal Services July 31, 1991 ET 91-0132 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-137 Washington, D. C.

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Reference:

Letter WM 89-0177 dated June 19, 1989 from B. D. Withers, WCNOC to NRC Subjects rocket No. 50-482: Response to NRC Bulletin No. 89-01, Supplement 2:

" Failure of Westinghouse Steam Generator Tube Mechanical Plugs" Gentlemen:

The purpose of this letter is to provide Wolf Creek Nuclear Operating Corporation's (WCNOC) response to NRC Bulletin No.

89-01, Supplement 2.

Bulletin 89-01, Supplement 2 requested that actions similar to those requested i;. NRC Bulletin 89-01 be extended to include all Westinghouse mechanical plugs fabricated from thermally treated Inconel 600.

As required by item 1 of Actions Reauested, WCNOC verified that the information contained in Table 2 of Addendum 2 to Revision 3 of WCAP-12244,

" Steam Generator Tube Plug Integrity Summary Report" for Wolf Creek Generating Station (WCGS) is correct for plugs fabricated from group 2 heats.

Specifically, WCNOC verified that the number of Vestinghouse mechanical plugs installed in the hot-leg and cold-leg side of each steam generator by heat number and date of installation is correct. Additionally, the plug operating temperatures for WCGS given in Table 2 were verified to be correct.

As required by item 2 of ReportinR Reauirements, the actions in Actions Recuented item 2 will be taken.

Installed Westinghouse rechanical plugs fabricated from Intonel 600 will be removed prior to the repair date identified in Table 2 of Addendum 2 to Revision 3 of WCAP-12244. Mechanical plugs fabricated from Inconel 600 will not be used in the future at WCGS.

The Reference submitted WCNOC's response to NRC Bulletin 89-01 which committed to an examination for primary water stress corrosion cracking on a

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sample basis of Wes

'ghouse mechanical plugs removed from the steam generators in accordan with Actions Reauested, item 2e.

At the time the Reference was submitted, the removal process involved a relaxation and pulling of the mechanical plug.

WCGS steam generator tubes are installed flush with the tube sheet which creates a greater potential for damaging the F([619~0 g icf (tjq?!,

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tube end weld when the plug is removed by the pulling method.

The current removal process entails drilling the mechanical plug.

This process destroys the plug _ but serves to minimir.e the potential for damage to_the_ tube end veld during the plug removal process.

However, the removal process destroys

_ the plugs which makes an examination impractical.

Therefore, it is WCNOC's intent to not examine the mechanical plugs after removal, if you have any questions concerning this matter, please contact me or Mr.

H. K. Chernoff of my staff.

Very truly yours, f

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Forrest T. Rhodes Vice President-Engineering & Technical Services FTR/aem cci L.'L. Gundrum.(NRC)

A. T. Howell (NRC)

R. D. Martin (NRC)

D.'V. Pickett (NRO)

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STATE OF KANSAS

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Forrest T. Rhodes, of lawful age, being first duly sworn upon oath says that he is Vice President Engineering and Technical Services of Wolf Creek Nuclear Operating Corporations that he has read the foregoing document and knows the content thereof that he has executed that same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

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4 37 Forrest T. Rhodes Vice President Engineering & Technical Services SUBSCRIBED and sworn to before me this 3/

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