ML20151G272

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Forwards Listed Documents Re Spring 1988 Insp of IGSCC, Including Design Rept for Recirculation & RWCU Sys..
ML20151G272
Person / Time
Site: Quad Cities Constellation icon.png
Issue date: 07/14/1988
From: Johnson I
COMMONWEALTH EDISON CO.
To: Murley T
Office of Nuclear Reactor Regulation
Shared Package
ML20151G274 List:
References
4921K, GL-84-11, GL-88-01, GL-88-1, NUDOCS 8807280255
Download: ML20151G272 (2)


Text

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[-} Commonwealth Edison One First National Plaza. Chicago, Cnois (L/ Chicago,ll!inois

' 7 Address Revy to: Post Office Box 767 60690 0767 PRIORITY ROUTING e July 14, 1988 First

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Mr. Thomas E. Murley, Director WD#

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Quad Cities Station Unit 2 "Spring 1988 Inspection of Intergranular Stress Corrosion Cracking (IGSCC) -

Generic Letter 84-11 and 88-01" NRC Docket Nos. 50-265 i.

Reference (a): Letter from I.,,M. Johnson to T.E. Murley dated June 13, 1988. --

Dear Mr. Murleys f In the referenced letter we reported a descri.ption of IGSCC flaws foundandtheanalyticalandrepairactionstakendur{ingtheSpring1988 refueling outage. In Reference (a), we agreed to provide a more detailed report within 30 days following the restart of Quad Cities Unit 2. The purpose of this letter is to transmit the following documents:

1) Design Report for Recirculation and Reactor Water Cleanup System Evaluation and Repairs Performed During the 1988 Refueling Outage at the Quad Cities Nuclear Power Plant, Unit 2, Structural Integrity Associates, Inc. Report No. SIR-88-01B, Vol. 2, Revision 0, Project No. CECO-090-1, June 1988.

This volume of the report covers the as-built reconciliation of the weld overlay repair and weld overlay examinations performed during the 1988 refueling outage with the analyses and designs presented in Volume 1.

2) Evaluation of End Cap Weld 02A-S10 Weld Overlay Repair Considering Ultrasonic Inspection Findings During 1988 Outage, Quad Cities Nuclear Power Station, Unit 2, Structural Integrity Associates, Inc. Report No. SIR-88-020, Rev. O, Project No. Ceco-090-7, July 1988.

Weld overlay 02A-S10 was originally applied in 1966. Preservice ultrasonic (UT) examination results were evaluated as flaws in the weld overlay material. The reported minimum remaining ligaments of these flaws were less than the standard or full structural weld overlay thickness. Analyses at that time demonstrated acceptabi-lity for continued service.

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., T.E. Murley July.14, 1988 e

This weld overlay was re-examined by UT at-the beginning of the recently completed 1988 Quad Cities Unit 2 refueling outage.

Detailed review of the UT data demonstrated no significant changes in the UT results.

A repair to this weld overlay was made during the 1988 outage by removing, by machining, a large portion of the existing weld overlay containing the reported flaws and a portion of the bane material. Liquid penetrant (PT) examination was performed at several intermediate stages during the metal removal to help understand the previous UT results. No crack-like flaws were observed in the weld overlay material. The original weld overlay thickness and width was then re-established by re-application of a weld overlay repair.

The repaired weld overley was then re-examined by UT and several IGSCC-like flaws were evaluated in the base material under the weld overlay repair. In addition, approximately 50 UT reflectors evaluated as "contamination cracks" were reported in the weld overlay material.

An extensive metallurgical examination of boat samples removed from this weld overlay was undertaken. These investigations did not reveal any crack-like defects in the weld overlay deposit which led to the UT signals.

A 3-D finite element analyses was performed assuming _that the UT reflectors were cracks. This report provides the details and results of this analysis. This extremely conservative "what if" analysis demonstrated the structural adequacy of the existing weld overlay, even assuming the weld overlay flawed.

This transmittal completes the reporting of analyses and weld overlay repair efforts for the 1988 Quad Cities Unit 2 refueling outage.

Please direct any questions you may have regarding this matter to this office.

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' Very truly yours, f . Vl l I. M. J ns Nuclear Licensin inistrator 1m Enclosure cc A.B. Davis - RIII, Regional Admin.

T. Ross - NRR QC Hesident inspector 4921K