ML17180B309
| ML17180B309 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/21/1995 |
| From: | Stang J NRC (Affiliation Not Assigned) |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| References | |
| GL-88-01, GL-88-1, TAC-M91690, NUDOCS 9507280066 | |
| Download: ML17180B309 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION Mr. D. L. Farrar, Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West III 1400 Opus Place, Suite 500 Downers Grove, IL 60515 WASHINGTON, D.C. 20555--0001 July 21, 1995
SUBJECT:
RECLASSIFICATION OF RECIRCULATION LOOP "B" WELD (202-1B-D4)
Dear Mr. Farrar:
By letter dated January 20, 1995, Commonwealth Edison Company (ComEd) proposed an alternate method for the reclassification of the Dresden, Unit 2 "B" recirculation loop weld from a "Category G" weld to a "Category E" weld in accordance with the guidelines of Generic Letter (GL) 88-01, "Intergranular Stress Corrosion Cracking (IGSCC) in 8WR Austenitic Stainless Steel Piping 0
dated January 25, 1988.
The proposal would reclassify recirculation loop 0 8 11 weld (202-18-D4) from a Category G weld to a Category E weld by applying a pro-active full structural weld overlay on the subject weld.
In accordance with GL 88-01, a Category G weld is a weld made of material susceptible to IGSCC and the weld has not been inspected; a Category E weld is a degraded weld mitigated either by applying a weld overlay or stress improvement.
Commonwealth Edison Company plans to perform the weld overlay during the upcoming refuel outage (D2Rl4).
The subject weld, joining the cast stainless steel recirculation pump casing to the 28-inch cast stainless steel suction elbow, is susceptible to IGSCC because the test data had shown that it contained low ferrite and high carbon content.
Commonwealth Edison Company stated that because of the highly attenuative nature of cast materials and the local physical obstruction that would restrict transducer movement ne~r the weld crown, a successful ultrasonic examination of the subject weld that would cover the complete weld volume cannot be assured.
Therefore, in lieu of performing a potentially inadequate ultrasonic examination of the subject weld~ ComEd proposed to apply a weld overlay in accordance with the requirements of GL 88-01 and NUREG-313, Revision 2.
After completion of the weld overlay, a baseline ultrasonic examination of the weld overlay will be performed.
However, in the January 20, 1995, letter, ComEd requested relief from GL 88-01 guidelines to perform an ultrasonic examination of the base material below the weld overlay because of the highly attenuative nature of ultrasonic waves in cast materials.
The staff has reviewed the proposal of weld reclassification as it is discussed in the January 20, 1995, letter. The staff finds reclassifying weld J.
202-18-D4 from a Category G weld to a Category E weld is in accordance with
~~I GL 88-01 guidelines and is acceptable.
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However, the staff will require a baseline inspection of the subject weld including the upper 25 percent of the base material below the weld overlay on a best effort basis to access the base material integrity. This non-destructive examination (NOE} of the base material below the overlay may be delayed until the first required inspection of the weld overlay in accordance with the guidelines of GL 88-01.
The delay is warranted because of the current lack of a calibration block for the specific weld.
Without the Galibration block, the NOE of the weld would not produce acceptable results.
If actual difficulties are encountered in the examination of the base materials, ComEd may submit a request for relief from inspecting the base material of the subject weld for the subsequent examinations if adequate justification can be provided.
In addition, ComEd should follow the provision of Code Case N-504 for the weld overlay design. The results should be maintained on site and be available for inspection.
If you have any questions concerning this issue please contact me at (301}
415-1345.
Docket No. 50-237 cc:
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'. ',1 Sincerely, Or1ginal signed by John F~ Stang, Senior Project Manager Project Directorate III-2 Division of Reactor Projects - III/IV O~fice of Nuclear Reactot Regulation (EGAl}
DOCUMENT NAME:
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D. L. Farrar Commonwealth Edison Company cc:
Michael I. Miller, Esquire Sidley and Austin One first National Plaza Chicago, Illinois 60603 Mr. Thomas P. Joyce Site Vice President Dresden Nuclear Power Station 6500 North Dresden Road Morris, Illinois 60450-9765 Mr. D. Bax Station Manager, Unit 2 Dresden Nuclear Power Station 6500 North Dresden Road Morris, Illinois 60450-9765 Mr. J. Heffley Station Manager, Unit 3 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 III 801 Warrenville Road Lisle, Illinois 60532-4351 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Chairman Grundy County Board Administration Building 1320 Union Street Morris, Illinois 60450 Dresden Nuclear Power Station Unit Nos. 2 and 3 John Willis, Coordinator Nuclear Campaign Greenpeace International 1436 U Street, NW.
Washington, DC 20009