ML20037B275
| ML20037B275 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, Zion  |
| Issue date: | 08/14/1972 |
| From: | Brian Lee COMMONWEALTH EDISON CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20037B272 | List: |
| References | |
| TASK-06-04, TASK-6-4, TASK-RR NUDOCS 8009100858 | |
| Download: ML20037B275 (2) | |
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Commonwealth Edison Company
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POST OfftCE BOX 767
- C M 8 C A G O, SLL$NOa5 60490 August 14, 1972 9
Mr. Boyce H. Grier I
Regional Director U.S. Atomic Energy Commission
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Directorate of Regulatory Operations Region III
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799 Roosevelt Road Glen Ellyn, Illinois 60137
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Dear Mr. Grier:
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Your. letter of June 29, 1972 requested that wejprovide,,
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. verification to your offic,e that valves important to safety [
installed or to be installed at our Zion, Quad-Cities and Dresden facilities meet minimum' wall thickness requirements'specified by.
applicable codes, standirds and procurement specifications.
This letter provides our present position on 'this matter and is of necessity different for the various. units at these facilitiei be-4 cause of differing stages of construction or operation.
We offer two general con'anents beforA discussing the specific facilities.
First, we believe any minimum' wall' thickness verification program should apply only to cast valves since previous deficiencies have been limited to cast' valves.
Secchd' we consider the requirement for 2% accuracy with ultrasonic inspection methods to be unrealistic.
Zion - At your request, dated March 27, 1972, we haJe, initiated a program to provide reasonable assu~rance that Class I cast valvec over 4-inch nominal size meet minimum wall thickness requirements.
This program was described in our letter to you dated May 4, 1972 and you subsequently informed us by letter dated June, 13, 1972 that you had no further questions on this program.
Wo.are still following the
, f program at Zion and the results w'ill be available at the site fo'r.
s review by your inspectors.
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Mr. Boyce H. Grier August 14, 1972 Dresden 2,'3 and Ouad-Cities 1,2 - On-February 18, 1972, General Electric Company completed ultrasonic testing of 10 valves in
- Quad-Cities Unit 2 for checking ' of minimum wall thickness.
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' 'l~v}Ive's,were selected as a representative sample of those cast valv,es ovbr 4-inch nominal s'ize located within the primary system pressure boundary, The results of this study indicated that minimum wall thickness was maintained for those valves checked.
,T_hese'yesults were reviewed with your inspector on March 17, 1972.
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- yWe believe that these results provide reasonable assurance that
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required minimum wall thicknesses have been maintained for those
' valves within the Quad-Cities 2 primary system pressure boundary.
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Furthermore, since the valves for Dresden 2 and 3 and Quad-Cities ldgnd'2 were purchased through common procurement, we believe this l
same conclusion applies to Dresden 2 and 3 and Quad-Cities 1.
t Dresden 5 - In,the 12 year operating history of this unit, we have 6
j experienced no problems with the integrity of valves within the pridary system pressure boundary.
All such valves successfully comp 4ete,d the initial hydrostatic test as well as all subsequent hydrostatic tests.
These tests have traditionally been considered L. --
as aciequ6te demonstration of pressure retentio'n capability.
We have endeavored without success to locate records which will provide l
evidence of minimum wall thickness.
Although it has been common
' ractice for valve manufacturers to make casting wall thickness L
p measurements to demonstrate conformance to drawings, there has been no code requirement to document these measurements.
In view of the foreg'oing and the very large radiation exposure burden which would result.from non-destructive examination of these valves, we do not bslieve any additional measures need to be taken to provide reason-able assurance that Dresden 1 valves meet minimum wall thickness requirements.
4-We would be happy to discuss this subject at your convenience.
Very truly yours,
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Assistant to thb President E
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