ML20090K013

Requests to Defer Scheduled Ultrasonic Examination of Two Unit 2 Welds During Current Refueling Outage

ML20090K013
Person / Time
Site:	Quad Cities
Issue date:	03/11/1992
From:	Schrage J COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9203180191
Download: ML20090K013 (4)

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Ccmmcnwealth Ediscn t

V 1400 Opus Pisce

[ Downers Grove. lilinois 00515 i

March 11,1992 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk

Subject:

Quad Cities Nuclear Power Station Unit 2 Deferral of lGSCC Ins aection Plan Welds from the Winter 1992 Refueling Outage (O2R11)

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Reference:

Conference call between CECO (J. Schrage, et. al.)

and NRR (D. Lynch, et. al.) on March 5,1992 Dr. Murley:

As discussed with your Staff during the referenced teleconference, Commonwealth Edison Company (CECO) is requesting to defer the scheduled ultrasonic examination of two (2) Unit 2 welds (28" Recirculation System welds) during the unit's current refueling outage (O2R11). These examinations are part of the inspection program for piping susceptible to intergranular stress corrosion cracking (IGSCC). The two (2) cast stainless steel elbow to cast stainless steel pump body welds (weld 02AS S15 on Recirculation Loop 'ds in the IGSCC program. This deferral request is based on theA as Category 'G' wel current accessibility and configuration of the welds.

A large whip restraint (cable tray design whip restraint) is located on each weld, with the tray of the restraint encompassing the weld surface. Removal of the restraint for insaection purposes necessitates cutting of the bolts holding the whip restraint.

Re nstallation would require replacement of the bolts. Based on the current working dose rate at the elbows (approximately 0.2 rem /haur), it is estimated that in excess of 6.4 person rem would be expended for the removal (and reinstallation) of each whip restraint.

Once the welds are accessible for inspection purposes, the current configuration (outside surf ace contour) of each weld is not conducive to obtaining a meaninciful examination. The contour of each weld is shown in Figures 1 (weld 02AS S1$)ddle of a and 2 (weld 02BS S15). As shown in the Figures. the wald crown is located in the mi trough approximately four inches wide. This configuration is too restrictive for proper placement and movement of the transducer search unit (s) to obtain sufficient weld coverage. In order to obtain a meaningful examination, machining of elbow material would be required, which would result n an additional radiation exposure for each weld.

Machining on the elbow would also necessitate detailed evaluations to ensure structural integrity is maintained. In addition to the configuration considerations, CECO does not currently possess a calibration block for this weld application which meets the a\\ g g requirements of ASME Section XI.

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i Dr. Thomas E. Murley 2-March 11,1992 For each weld, CECO has obtained ferrite measurements (presented in the Figures) for the elbow, weld, and pump casing. The high value of the measured ferrito numbers indicate that the welds should be resistant to IGSCO. In addition, CECO has implemented the use of Hydrogen Water Chemistry (HWC) during power operation at Quad Cities Station Unit 2. The use of this system during power operation fudher

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minimizes the susceptibility of the welds to IGSCC. The combination of high ferrite measurements, and the use of HWC during power operation provides assurance that the deferral of the inspection for one refuel outage poses no safety concern.

As discussed with your Staff in the referenced teleconference, CECO is 'ursuing an evaluation to justify the reclassificatio,1 of these welds to Category 'A'in the GSCC program. The results of that evaluation will be submitted for Staff review, CECO appreciates the Sta*f consideration of this deferral request. Please contact this office should fudher information be required.

Respectfully, j

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i j )(C b ohn L. Sc rage Nucl ar Licensing Administrator B

Figure 1: Diagram of Weld 02AS S15 Figure 2: Diagram of Wold 02BS-S15 cc: A. Bed Davis, Regional Administrator, Region 111 L.N. Olshan, NRR Project Manager-Ouad Cities D. Lynch, Project Manager Ouad Cities T.E. Taylor, Senior Resident inspector Ouad Cities

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