ML20101R570
| ML20101R570 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 04/09/1996 |
| From: | Kraft E COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ESK-96-055, ESK-96-55, GL-94-03, GL-94-3, NUDOCS 9604160363 | |
| Download: ML20101R570 (5) | |
Text
e Comnwnwcahh litison Company Quad Citin Genes iting station 2271u 2G$th Agenw North a
Cordova. I1. 61212-9 '-60 Tel Mm 5 4-221I ESK-96-055 April 9,1996 U. S. Nuclear Regulatory Conunission Attn: Document Control Desk Washington, D.C. 20555
Subject:
Quad Cities Nuclear Station Unit 1, Core Shroud Examination Results NRC Docl gi No. 50-254 i
Referrn (a)
NRC Generic Letter 94-03, "Intergranular Stress Corrosion Cracking of Core Shrouds in Boiling Water Reactors" (b)
BWRVIP document GENE-523-113-0894, BWR Core Shroud Inspection and Evaluation Guidelines, dated September 1994.
(c)
BWRVIP Cor: Shroud NDE Uncertainty and Procedure Standard, dated November 21,1994.
(d)
J. L. Schrage (ConId} to USNRC letter, Quad Cities Station Unit 1 Core Shroud Inspection Plan, dated November 16,1995.
The purpose of this letter is to provide the final results of the Quad Cities Station Unit I core shroud examinations. The examinations were performed in conjunction with the comprehensive shroud repair to assure that structural integrity of the core shroud is maintained. The examinations of the reactor core j
shroud were performed in accordance with Comed's commitment to NRC Generic Letter 94-03 (Reference d) and BWRVIP guidelines (References b and c). The examinations were completed on March 31,1996.
The core shroud examinations consisted of performing ultrasonic examination (UT) of the vertical shroud j
i welds that could be accessed using the remote a:c2 scanner system and enhanced visual examination of the remaining design reliant welds and structures. The ultrasonic examinations were performed in accordance with the BWRVIP " Standards for Ultrasonic Examination of Core Shroud Welds" and the visual examinations were performed in accordance with the BWRVIP " Standards for Visual Inspections of Core Shrouds" In addition, eddy current was used as an aid in identifying the location of the ring segment welds associated with the shroud head flange ring, the top guide support ring and the core plate support ring.
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April 9,1996 The following is a summary of the core shroud examination scope and results. Detaik of the specific areas examined and the results of the examinations are presented in the attached Table I and Figure 1.
The ultrasonic examination scope consisted of shroud vertical welds (V14 through Vl9) located between horizontal welds H3/H4 and H4/H5 (i.e. beltline region). Approximately 27 inches, or between 31% and 36% of the total length of each vertical weld was examined. These exannnations resulted in no reportable indications.
During the UT examination of vertical welds V14 and V16, OD geometry was noted at the opposite side of the vertical weld. Subsequently, these suspect areas were visually examined resulting in the identification of an uneven surface due to welding discontinuities and heavy grinding marks from the fabrication process. The UT examinations and subsequent enhanced visual examinations resulted in no reportable indications in the area ofinterest.
l The enhanced visual examination scope consisted of the ring segment welds associated with the shroud e
head flange ring, top guide support ring, core plate support ring; vertical welds V5-V7 and V26-V28, inclusive; the H8 and H9 horizontal welds at the shroud repair hardware locations; and the shroud repair hardware attachment sites at the shroud head flange ring and the jet pump support plate. These examinations resulted in no reportable indications.
While using eddy current testing to locate the ring segment welds associated with the core plate support ring, difficulty with interferences associated with the adjacent jet pumps and jet pump sensing lines was experienced. This resulted in verifying the location of one of the six segment welds with the eddy current tool. The fabrication records were reviewed and depict that the rmg is fabricated with six segment welds equally spaced. Based on the location of the identified segment weld, coupled with the fabrication records, these six locations were visually examined. However, to be conservative, the balance of the core plate support ring accessible surfaces were visually examined. These enhanced visual examinations resulted in no reportable indications in the area ofinterest.
In summary, the examinations of the core shroud design reliant structures performed at Quad Cities Unit I per the Inspection Plan (Reference d), resulted in no reportable indications in the areas ofinterest.
To the best of my knowledge and belief, the information contained in this document is tme and correct. In some respects this document is not based on my personal knowledge, but on information furnished by other Comed employees, contractor employees, and/or consultants. Such information has been reviewed in accordance with company practice, and I believe it to be reliable.
l l
3 U.S. NRC 3
April 9,1996 i
l If there are any questions concernmg this matter, or need for further clarification, please contact this office.
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i Sincerely,
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/Ohls Site Vice President Nota'rv P6blit.
Dated Quad Cities Station
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UNDA LEE STOERMER Notary Pubhe,StateWlilmois D
My Comassen E@es11/1W j Attaclunents: (1)
Table 1 - Quad Cities Unit 1 Core Shroud Examination Summary (2)
Figure 1 - Quad Cities Unit 1 Core Shroud Examination Roll Out 1
cc: H. J. Miller, Regional Administrator - Rlli R. M. Pulsifer, Project Manager - NRR C. G. Miller, Senior Resident inspector - Quad Cities Office of Nuclear Facility Safety - IDNS D. C. Tubbs, R. J. Singer, MidAmerica Energy Company l
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i TABLE 1 QUAD CITIES UNIT 1 CORE SilROUD EXAMINATION
SUMMARY
Component Area inspected Inspection Results Shroud Head Flange Enhanced visual examination of ~ 12" length of ring No Reportable Ring Segment material encompassing each weld. Verified all 4 weld Indications Welds:
locations with eddy current testing. Inspected OD, ID l
VI through V4 and Top ofidentified surface areas.
Top Guide Support Enhanced visual examination of ~ 12" length of ring No Reportable l
Ring Segment material encompassing each weld. Verified all 6 weld Indications i
locations with eddy current testing. Inspected OD, ID 1
V8 through V13 and Bottom ofidentified surface areas.
Core Plate Support Enhanced visual examination of 100% of the accessible No Reportable j
Ring Segment surfaces or 55% (356") of OD and Bottom of ring.
Indications Welds:
Verified I of 6 weld locations with eddy current tool V20 through V25 due to access constraints.
Vertical Welds V5, Enhanced visual examination of ~ 33" of each weld No Reportable V6 and V7 or 100% of each weld from the OD surface. ( ID Indications surface was not accessible) l Vertical Welds V14, Ultrasonically examined 27" or between 31% and 36%
No Reportable l
Vl5,V16,Vl7,Vl8 of each weld.
Indications and Vl9 i
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Vertical Welds V26, Enhanced visual examination of ~ 14" of each weld No Reportable l
V27 and V28 or 25% of each weld from the OD surface. ( ID surface Indications was not accessible)
Jet Pump Support Enhanced visual examination of ~12" of weld in area of No Reportable Plate to Shroud Weld repair hardware attachments at 4 locations: 20",110",
Indications H8 200" and 290 Az.
Jet Pump Support Enhanced visual examination of ~12" of weld in area of No Reportable Plate to RPV Weld repair hardware attachments at 4 locations: 20",110",
Indications H9 200 and 290" Az.
Shroud Head Flange Enhanced visual examination of repair hardware No Reportable Ring attachment sites both prior to and following EDM at 4 Indications locations: 20",110*,200' and 290* Az Jet Pump Support Enhanced visual examination of repair hardivare No Reportable Plate attachment sites both prior to and following EDM at 4 Indications j~
locations: 20",110",200" and 290" Az 4
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SHROUD OD SURFACE DEVELOPMENT Q1R14 ELAMINATIONS OF CORE SHROUD
- OEuous A=t s vsuAuv Exiua.C mm - OE,.Ons a=CAs utrus=ctav Ex*w=E0 QUAD CITIES UNIT 1
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