ML20234C217
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UNITED STATES l-Y ATOMIC ENERGY COMMISSION I*I h1H 'l WASHINGTON, D.C. 20545 48 RECEIVED
%ne March 5, 1973
, Docket No. 50-254 gg73gg g pg [2 47 e S. ATOM.C t.N.a:w ( COMM.
ADVISORY COMMITTEE ON FE/,CTOR SAFEGUARDS Mr. Harold G. Mangelsdorf Chairman, Advisory Comittee on Reactor Safeguards U. S. Atomic Energy Comraission Washington, D. C.
20545
Dear Mr. Mangelsdorf:
Sixteen (16) copies of the following are transmitted for the Committee's information:
Letter from Commonwealth Edison Company dated February 16,
- 1973, informing of a high frequency vibration which was heard in the Quad-Cities Unit 1 reactor building in the vicinity of the pressure suppression chamber.
Letter from Commonwealth Edison Company dated February 16, 1973, reporting that a limit switch on a Quad-Cities Unit 1 main steam isolation valve failed.
I Letter from Commonwealth Edison Company dated February 26, 1973, reporting the set point drift of a switch at Quad-Cities Unit 1.
Sincerely, 7
ggf h' Donald J.
ovholt Assistant Director for Operating Reactors Directorate of Licensing
Enclosures:
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SUFFISBNT NO.164 CATEGORY B Q 195.
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Quad I111 s 1 April 30, M [
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SUBJECT:
1.
DEIECTION OF HIGH FR8QUENCY VIBRATION 2.
MSLIV LIMIT SWITCH FAITAM 1.
Licensee letter February 16, 1973 reports occurrence and WRS DO investigate n of high frequatscy vibration noted on January 16, g
1973 in vicinity of pressure-suppression chamber naar' location of LPCI pipe penetration from drywell. Vibration most notice-able at reduced power ( 70%) and at 80-90% nominal recire pump capacity.
Licenses determined kibrations not excessive and Vibration monitoring discontinued pending installation of permanent monitoring system.
2.
Licensee letter February 16, 1973 reports details of MSLIV limit switch failure detected during routine valve exercise test on February 3, 1973, cause unk.nown. Further testing shou &d normal operation.
Licensee concludes safety significance nil because of small probability of required coincident failures / occurrences.
In view of the Oconee vibration / loose parts incident and the multiplicity of problems associated with MSLIV's, a REG report on these items is recommended.
The enclosed material should be retained, pending final resolution.
(WAB) 1
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l FILE: Quad Cities 1 ACRS omet >
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Form AEC-318 (Rev. 9-53) # ECM 0240
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