ML20117M570
| ML20117M570 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Dresden |
| Issue date: | 05/27/1983 |
| From: | Rybak B COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20114G054 | List:
|
| References | |
| FOIA-84-616 6665N, NUDOCS 8505170129 | |
| Download: ML20117M570 (3) | |
Text
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- ff Commonwealth Edison
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-J4 May 27, 1983
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Mr. James G. Keppler, Regional Administrator
--~l Directorate of Inspection and v
qg Enforcement - Region III
.U.S.
Nuclear Regulatory Commission xi 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Dresden Station Unit 2
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Main Steam Line Snubber Failure NRC Docket No. 50-237 Reference (a):
B. Rybak letter to J. G. Keppler dated May 13, 1983.
(b):
B. Rybak letter to 3. G. Keppler dated May 24, 1983.
Dear Mr. Keppler:
Attached is a report prepared by Sargent & Lundy wh.ich investi-gates whether binding between the snubbers and pipe clamps is a problem on Dresden Unit 2 considering actual and design line thermal growth.
The results of this report will be factored into a program designed to visually determine if clamp interference does, in fact, exist.
As committed to the NRC, this plan is now scheduled for submittal June 3, 1983 and will be implemented during the 62-day snubber inspection.
We are also providing an update of the continuing investigation to resolve test thermal growth discrepancies.
At this time S&L is reviewing additional test data which they had requested be taken during the last Dresden 2 startup.
They are also working with Wyle Labs to investigate the possibility of loss of accuracy of the LVDT units.
The results of the initial phase of this investigation and possible future actions will be transmitted to you June 3, 1983.
If there are any questions regarding the above, please contact this office.
Very tr ly yours, 8505170129 840914
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PDR FOIA BARFIELB4-616 PDR B. Ry Nuclear Licensing Administrator im cc:
NRC Senior Resident Inspector - Dresden w/o Att.
R. Gilbert - NRR w/Att.
Attachments 6665N JUN 11993 w
SARGENTQ LUNDY EN GIN EERO CHICAS$
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May 26, 1983 Project No.: 5486-23 Commonwealth Edison Company Dresden Unit-2 Determining Snubber Binding in the Five Failed Main Steam Snubbers Mr. R. H. Mirochna Commonwealth Edison Company P. O. Box 767 Chicago, Illinois 60690 Dear Mr. Mirochnar
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Per Commonwealth Edison's request, the evaluation to determine
.anubber binding in the five failed Main Stean Snubbers has been co:.pleted.
The evaluation was conducted utilizing a typical fabricated snubber model (PSA-10) built to duplicate the five actual design-conditions.
Encioned please find a copy of the evaluation's procedure, which outlines the preparations as well as the design condition input for the test purpose.
The design condition input consists of snubber thermal movements (axial and lateral) as measured by the LvDT's and as expected b'y computer analysis.
i' The results of the evaluation indicate that, for the five failed snubbers, thermal movements for either LVDT's or design condition would not cause binding or' surface-to-surface touching at either i
pipe clamp and/or rear end bracket.
This indicates that since~sur-i face-to-surface touching was observed during the plant outage, it definitely did not result from either' design condition or actual pipe thermal response.
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e SARGENT O LUNDY EN GIN EERG CHICA2O
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Mr. R. H. Mirochna May 26, 1983 Commonwealth Edison Company Project No.: 5486-23 Page 2 of 2 l
Also enclosed are photographs of the clamp and rear and bracket of the test model, representing the five snubbers at hot condition.
If you have any questions regarding the enclosed procedure and
. results, please call me.
Yours very truly, f6 S. E. Azzazy Supervisor Engineering Mechanics Division SEA:sp Enclosure copics:
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E. R. Zebus R. H. Jason J. M. Nosko A. Walser P. Gazda GTK/ SEA EMD File No. 043699 e
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