ML20081F549
| ML20081F549 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 10/27/1983 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20081F554 | List: |
| References | |
| 7490N, NUDOCS 8311030129 | |
| Download: ML20081F549 (2) | |
Text
- _.
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'x Commonwealth Edison
/ One First Nation +1 Plua, Chicago. Ithnois O'
7 Address R ply to: P:st Offica Box 767 (j Chicago, Illinois 60690 s
October 27, 1983 Mr. Harold'R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Byron Generating Station Unit 1 Preservice Inspection NRC Docket No. 50-454 Reference (a):
March 1, 1983 letter from T. R. Tramm to H. R. Denton.
Dear Mr. Denton:
This is to inform you of the results of the preservice examination of the Byron 1 steam generators and pressurizer vessels.
This examination was described to the NRC in reference (a).
NRC concurrence is also requested in our decision to not pursue preservice repair of one set of ultrasonic indications in a pressurizer weld.
During the performance of Byron's pre-service inspections, several indications were identified through the ultrasonic testing of celds in the Unit.1 steam generators and pressurizer.
After further inspection and evaluation, five indications in the steam generators were determined to be rejectable to ASME Section XI criteria.
All five steam generators indications will be repaired.
On the pressurizer, however, cdditional inspectons showed that the indications were smaller than indicated by the 0.D. ultrasonic exam.
As a result, the indications in the Unit 1 pressurizer weld PC-01 are not being repaired.
This decision is based upon careful consideration of the following' items:
1.
Radiography and ultrasonic testing from the I.D. of the pressurizer indicate that the ultrasonic reflections are anomalies which were apparently amplified due to the geometry of the 0.0.
examination surface.
2.
Based upon alternate NDE methods and the location of the indications, the sound reflectors have been characterized as tight slag lines.
3.
Fracture mechanics indicates.that these flaws cannot grow signficantly even when applying the most conservative assumptions and calculating growth for the largest possible indication.. Repair of these indications would not be required if they were detected during inservice inspections.
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f I If 8311030129 831027 PDR ADOCK 05000454 G
/
o H. R. Denton October 27, 1983 4.
These indications exist in a low stress, non-critical area of the pressurizer where actual thermal stresses were not likely to approach the calculated stresses.
5.
A~ field repair of this weld presents concerns which must be
. weighed against the actual signficance of the indications.
Attachment A to this letter is a report which summarizes the inspection results.
It also documents the fracture mechanien evaluation of the pressurizer indications.
This information was reviewed with the
.NRC staff.in a meeting on October 7, 1983.
We would be pleased to
. discuss it further at your convenience.
Please direct any questions'to this office.
Prompt NRC concurrence on this matter is requested.
One signed original and fifteen copies of this letter and the attachment are provided for your review.
Very truly yours, MW.
c T. R.
Tramm Nuclear Licensing Administrator 1m-
.a 7490N J