ML19332C780
| ML19332C780 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 11/20/1989 |
| From: | Trzyna G COMMONWEALTH EDISON CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8911280540 | |
| Download: ML19332C780 (2) | |
Text
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'y Commonwealth Edison 1
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__ - 72 West Adams Street, Chicago, Illinois.
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Address R; ply tof Post OffEGdx76E p
y Chicago, Illinois 60690 0767.-
November 20, 1989 Director of Nuclear Reactor Regulation US Nuclear Regulatory Commission Mail Station PI-137 1
Washington, DC 20555
Subject:
Zion Nuclear Power Station, Unit 1 i '
License No. DPR-39
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-NRC-Docket No. 50-295 Steam Generator Girth Held Insag.ttion
Reference:
(a) November 16, 1989, telephone conversation
'between NRR/ Ceco personnel Gentlemen; i
During the recent Zion Unit I refueling outage, ultrasonic examinations were performed on the steam generator D upper shell to transition cone girth weld. During the course of these examinations, indications were u
detected which exceeded the allowable standards of IHC-3000 (table IHB-3511-1).
The total population of indications included both surface and subsurface reflectors.
Based upon these results, the extent of the ultrasonic-examinations was expanded to' include the girth weld-in steam generator C.
L' Based upon the indications'found in steam generator C, the examinations were
-expanded to include steam generators A and B.
All the UT surface indications confirmed by magnetic particle testing were removed by grinding and blending. Complete removal ~of all surface indications was verified by MT.
The remaining embedded indications which exceeded 501. of DAC were dispositioned by fracture mechanics to demonstrate their acceptance by the criteria of the ASME Code, Paragraph IHB-3600.
The following table describes-the bounding subsurface indication in each generator-(all dimensions in inches):
Generatet
_Ind_
2a Dim 1 Dim S Dim Y Dim alL J Lti% L.
A 13 0.06 0.80 0.58 1.0 0.38 8.2 B
2 0.37 1.70 0.52 1.0 0.11 5.1 C
9 0.35 0.50 1.48 1.0 0.35 4.7 D
32 0.47 0.625 0.45 1.0 0.38 6.4
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i Dir. Of Nuclear Reactor Reg.
- -2 November 20, 1989 The preceeding indications as well as all embedded indications which exceeded the standards of table IHB-3511-1 (1980 Code, 1981 Addison) were subjected to a fracture evaluation, using the guidelines of Appendix A of Section XI. The analyses completed were specific to the Zion steam generator girth welds.
The detailed technical basis behind these analyses will be submitted separately, but the approach was the same as that used for the flaw evaluation handbook submitted earlier for the Byron and Braidwood steam generators and pressurizers. A complete description and details may be found I.
in Hestinghouse HCAP-11063, " Background and Technical Basis, Handbook on Flaw L
Evaluation, Byron and Braidwood Units I and 2" by Y.S. Lee and H.H. Bamford.
The flaw evaluations completed for Zion Unit I have been based on a
-stress analysis performed with the same care and considerations as that performed for Indian Point 2.
The conclusion reached was that the indications l'
are all acceptable by a wide margin.
Commonwealth Edison has also committed to perform a more extensive examination of the " boat". specimens that were retrieved auring our inspection of the' steam generators.
The initial results of this metallography may be available by mid-December,'however, the results will not be finalized until the work is completed by Stanford Research.
He will be available to review the results of this analyses with your personnel when the analyses of the data is complete.
Please direct any questions that you may have regarding this matter i
to this office.
Very truly yours, 1
X1 G.E. Trzyna l
Nuclear Licensing Administrator I
cc: Chandu Patel-NRR l
R.A. Hermann-NRR Senior Resident Inspector-Zion l
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