ML17187B091
| ML17187B091 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/04/1997 |
| From: | Stang J NRC (Affiliation Not Assigned) |
| To: | Johnson I COMMONWEALTH EDISON CO. |
| Shared Package | |
| ML17187B092 | List: |
| References | |
| TAC-M96902, NUDOCS 9709150241 | |
| Download: ML17187B091 (3) | |
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~o UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555--0001
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Ms. Irene Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West-III 1400 Opus Place, Suite 500 Downers Grove, IL 60515 September 4, 1997
SUBJECT:
FOLLOW-UP EVALUATION OF WELD OVERLAY REPAIR OF RWCU NONREGENERATIVE HEAT EXCHANGER TUBESIDE INLET NOZZLE - DRESDEN, UNIT 3 (TAC NO.
M96902)
Dear Ms. Johnson:
By letter dated September 16, 1996, Commonwealth Edison Company (ComEd) informed the NRC that through-wall cracks were identified in the inlet nozzles to the reactor water clean up (RWCU) nonregenerative heat exchangers in both
- the *A" train and the ~B" train. The identification of the cracking was during a forced maintenance outage in September 1996.
The cracks were caused by intergranular stress corrosion cracking (IGSCC).
- ComEd's interim fix was to repair the *A" train nozzle with.a full structural weld overlay and iscilate the *e" train. This condition was to be maintained for app~oximately 6 months of operation until the next refueling outage*(D3Rl4).
The refueling outage
.started on March 18, 1997.
During D3Rl4, ComEd modified the pl~nt to (1) remove the entire *A" train of the RWCU, and (2) replac~d the *B" train RWCU piping and heat exchanger nozzles with material that is less susceptible to IGSCC~ ComEd provided additional information in letters dated September 20,
- 1996, and January 14, 1997.
- The subject weld repair has already been removed from service at Dresden, Unit 3.
The staff had reviewed ComEd's weld overlay repair prior to restart of Dresden, Unit 3, from a forced maintenance outage in September 1996, and had determined that the subject repair was acceptable for a short~term operation. However, the subject weld overlay repai~ did not completely meet American Society of Meehanical Engineers Bo.iler and Pressure Vessel Code Case N-504-1 because the ultrasonic inspection of the completed weld overlay was not performed.
Therefore~ a complete staff evaluation of the repair was required. The enclosed safety evaluation is a supplemental evaluation.
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Based on the staff's evaluation, it was determined that the design and fabrication of the subject weld overlay meet the guidelines of NUREG-0313, Revision 2.
Therefore, the staff concluded that the structural integrity of the repaired weld was maintained during the short-term service from September 1996 until March 1997 when Dresden Unit 3 shut down. *for its refueling.outage.
Docket No. 50-249 Sincerely, Or :j_ gin.al ~i gn~d" by
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John *F. ~tang'~ Senior:. Pr*oject Manager Project D,i rei:torate. I I r""'t
- . Dtvision.of.R~actor P~o)e~ts - Ill/IV
, *Office~o~ Nucl¢ar-Reactor:~egulation
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Enclosure:
Supplemental Saf~~~.'*E~alu~ti()Jl'*;;(,' '.:
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see next page Distribution:
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R. Capra J.* Stang E. Adensam~ EGAl W. Koo, 07D4 DOCUMENT NAME:
DR96902.LTR To receive a copy of this document, indicate in the box: *c* = Copy without enclosures "E" = Copy with enclosures "N" = No copy OFFICE Pl : P DLl--1-2 1e LA: POI 11-2 6'
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NAME J' T~ tl6 CMOORE II RCAPRA,._....
DATE QI /). /97 09/? /97 J
09/o'I /97
~ FICIAL RECORD COPY
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I. Johnson Conmonwealth Edison Company cc:
Michael I. Miller, £squire Sidley and Austin One First National Plaza Chicago, Illinois 60603 Site Vice President Dresden Nuclear Power Station
.6500 North Dresden Ro~d Morris, Illinois 60450-9765 Station Manager Dresden Nuclear Power Station.
6500 North Dresden Road Morris, Illinois 60450-9765 U.S. Nuclear Regulatory Commission Resident Inspectors Office Dresden Station 6500 North Dresden Road Morris, Illinois 60450-9766 Regional Administrator U.S. NRC, Region Ill 801 Warrenville Road Lisle, Illinois 60532-4351 Illinois Department of Nuclear Safety Office of Nuclear Facn ity Safety 1035 Outer Park Drive Springfield, Illinois 62704 Chairman Grundy County Board Administration Building 1320 Union Street Morris, Illinois 60450 Document Control Desk-Licensing Conunonwealth Edison Company 1400 Opus Plate, Suite 400 Downers Grove, Illinois 60515 Dresden Nuclear Power Station Unit Nos. 2 and 3
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