ML20083A282

Transmits Preliminary Results of Quad Cities Station Unit 2 Core Shroud Exams,Performed Prior to Installation of Shroud Repair Hardware

ML20083A282
Person / Time
Site:	Quad Cities
Issue date:	05/02/1995
From:	Schrage J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9505100140
Download: ML20083A282 (4)

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-May 2,1995 U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk

Subject:

Quad Cities Nuclear Station Unit 2 Core Shroud Examination Results NRC Docket No. 50-265

References:

(1) NRC Generic Letter (GL) 94-03, Intergranular Stress Corrosion Cracking of Core Shrouds in Boiling Water Reactors".

(2) BWKVIP document GENE-523-113-0894, BWR Core Shroud Inspection and Evaluation Guidelines, dated September 1994.

(3) BWRVIP Core Shroud NDE Uncenainty and Procedure Standard, dated November 21,1994.

(4) J.L. Schrage (Comed) to USNRC letter dated January 16,1995 (Quad Cities Station Unit 2 Core Shroud Inspection Plan).

This letter transmits the preliminary results of the Quad Cities Station Unit 2 core shroud examinations, which were performed prior to installation of shroud repair hardware. The exam nations were performed in conjunction with a comprehensive shroud repair to assure that structural integrity of the core shroud is maintained. The examinations of the reactor core shroud were performed in accordance with Comed's commitment to NRC Generic Letter 94-03

[ References (1) and (4)] and BWRVIP guidelines [ References (2) and (3)].

The core shroud examinations were subdivided into two groupings: prior-to-repair examinations and post-repair examinations. The examinations to-date havbe focused on the prior-to-repair grouping. These examinations consisted of ultrasonic examination of the venical shroud welds (accessible to the area scanner system) and visual examinations of the shroud which would be obscured by, or result in limited examination, by the presence of the shroud repair hardware. The repair hardware will be installed at four locations, equally spaced around the circumference of the shroud.

The scope of the examinations and results were as follows:

o Ultrasonic examination of the shroud vertical welds (V14 through V19) lom.d between horizontal welds H3/H4 and H4/H5 (i.e. beltline region). The tiltrasonic examinations were performed between April 13,1995 and April 15,1995 and resulted in no reponable indications. Apfroximately 27 inches of each venical weld (greater than 30% of the total weld length) wa: examined. See the attached map for details of the UT examinations.

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o Enhanced visual examination of the shroud head flange ring, venical weld V6 and V26, top guide suppon ring, core plate suppon ring and the shroud repair hardware attachment sites ,

at the jet pump suppon plate. The visual examinations were performed between April 16,.. l 1995 and' April 20,'1995 and resulted in minor indications (3 separate indications less than l or equal to 2 inches in length). One indication (3/4" in length) was noted in the shroud ,

i head flange ring. The indication is located in the heat affected zone (HAZ) of the fillet weld which connects the steam dam to the flange. . Two indications (1" and 2" in length,-  !

circumferentially orientated) were noted in the core plate suppon ring. These indications are associated with the heat affected zone (HAZ) of horizontal weld H5. However, these indications in the core suppon flange are considered insignificant because the shroud repair has been designed to structurally replace the shroud horizontal welds. It should be noted .

that the ring segment welds associated with the chroud head flange ring, the top guide suppon ring and the core plate support ring were not located visually due to machining of the rings / welds during original fabrication. Therefore, all of the accessible surfaces were  :

visually examined to ensure coverage of the ring segment welds. See the attached table and I map for details of the visual examinations.  ;

The post repair examinations are scheduled to be performed during the week of May 7,~ 1995 and will consist of visual examination of the balance of the accessible surfaces of the shroud head flange ring, top guide support ring and core plate support ring and visual examination of vertical welds V5, V7, V27 and V28 which are accessible at the OD surface. The examination coverage of the ,

vertical welds will be 12" at each weld location. As previously committed to in Reference (4),

Comed will provide the final results of the examinations to the NRC staff within thirty days from i the completion of the shroud examinations.

To the best of my knowledge and belief, the analyses and evaluations contained in these documents are true and correct. In some respects these documents are not based on my personal knowledge, but on information furnished by other Commonwealth Edison employees, contractor employees, and/or consultants. Such information has been reviewed in accordance with company practice, and I believe it to be reliable.  ;

If there are any questions concerning this matter, or need for further clarification, please contact this office.

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-p Attachment 1 Prior-to-Repair Enhanced Visual Inspection Summary

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Attachment 2 Cc,re Shroud UT Examination Maps cc: J. B. Manin, Regional Administrator - RIII R. M. Pulsifer, Project Manager - NRB  ;

C. G. Miller, Senior Resident Inspector - Quad Cities .

Office of Nuclear Facility Safety - IDNS  :

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- Attachment 1 l Erior-to Renair Fnhanced Visual Inspection Summarv Component Area Inspected Inspection Results -

Shroud Head 43" at 4 equally spaced locations total of 172" or 3/4" long indication Flange 25% of ring; Inspected OD, ID and Top of ring at 290 in steam dam 1 at 20*,110*,200",290 Az to ring fillet weld i HAZ Top Guide 43" at 4 equally spaced locations total of 172" or No Reponable Flange 25% of ring; Inspected OD and bottom of ring Indications  :

at 20*,110*,200*,290 Az Core Support 24" at 4 equally spaced locations total of 96" or 2" long indication at Flange 15% of ring; Inspected OD and bottom of ring 20 in H5 HAZ at 20",110",200a,290" Az 1" long indication at 200 in H5 HAZ Venical Weld 12" or 36% of weld, inspected OD surface, ID not No Reportable  !

V6 at 200* Az accessible Indications Venical Weld 55" or 100% of weld, inspected OD surface, ID No Reponable V26 at 110* Az not accessible Indications ,

Shroud Ledge to 10" of weld in area of repair attachments at 4 No Reportable Shroud locations; 20*,110*, 200*,290" Az Indications .

H8 Weld I

Shroud Ledge to 12" of weld in area of repair attachments at 4 No Reportable RPV locations; 20*,110", 200",290* Az Indications H9 Weld l

Shroud Ledge in Examined face of plate in area of repair No Reportable l Area of Repair attachments; approximately 150 square inches at 4 Inscations j Attachments locations; 20 ,110*, 200*,290* Az ,

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f Attachment 2 Core Shroud Examination Maps

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EXAMINATIONS OF CORE SHROUD E : "'*" ."ll' 37.ld"l";"l-.

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