ML20234E918
| ML20234E918 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Quad Cities |
| Issue date: | 09/20/1972 |
| From: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Seiss C Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20234A777 | List:
|
| References | |
| FOIA-87-40 NUDOCS 8707080041 | |
| Download: ML20234E918 (2) | |
Text
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UNITED STATES ATOMIC ENERGY COMMISSION I*
WASHINGTON, D.C. 20545 September 20, 1972 Docket No. 50-265 ES N'I 00 3l E
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p Dr. Chester P. Siess Chairman,L Advisory Comittee on Reactor Safeguards U. S. Atomic Energy Comission Washington, D. C.
20545
Dear Dr. Siess:
Sixteen (16) copies of the following am transmitted for the Conrnittee's
'information:
Letter from Commonwealth Edison Company dated September 6, 1972, reporting failure of seven suppression chamber to J.
. drywell vacuum breaker valves to test properly during a 4
routine inspection of Quad-Cities Unit No. 2.
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Sincerely,
.+
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Donald J.
,o olt Assistant Dimetor for Operating Beactors Directorate of Licensing Enclosums:
As stated p~n
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/.(, (.,' 4 0FFICIAL USE ONLY SUFFLEMENT No. 157 CAT 500RY B dO September 17, 197t h N [
omad Cities Unit _1 d e_,
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3 01 Malfunction'of Three Valves in RCIC System j
ACRS Commomeeslth Edison company TWX dated September 4.1972 reports that, during a routine test, two valves in the BCIC System failed to close and another failed to open. Lead was redueed, i
the HPCI system tested satisfactorily. Valve repair was initiated.
l Coasnonwealth Edison Company letter dated September 11. 1977 reports further on the incident. The cause is believed to be maladjusted DC breakers in two esses and a failed torque j
switch in the third. The breakers. wore readjusted and the torque switch replaced. Normal operation was restored.
l ACTION This matter should be discussed with the Regulatory Staff since it involves a common mode failure and multiple failure of valves in a primary system.
The enclosed material should be retained until the reca===aded
'ACRS review has been completed.
(JCM)
Quad Citios Unit 7 4
HMH Hultiole Failures of Torus to Drywell Vacuum Breaker Valves ACRS C-_
-walth Edison Company letter dated September '6.1972 reports further on the failure of six drywell to torus vacous breaker valves to close properly (four had their disco 1" eff the seat).
The difficulties were traced to sacessive friction in the pivot shaft and improper position switch settings. Repairs were made and proper operation restored. Unit 1 valves will be inspected t
The investi ation is continuing and
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at the first opportunity.
S design changes are being considered.
ACTION This problem should be discussed with the Regulatory Staff since excessive leakage through the vacuum breakers can bypass the suppression pool and result in overpressurising the containment for the small LOCA.
The enclosed u.aterial should be retained until the recommended ACRS revien has been completed.
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