ML20085F009

Final Deficiency Rept Re Corrosion in MSIV Operators. Initially Reported on 750417.Corroded Cylinders Replaced W/ Cylinders from Hydro-Line

ML20085F009
Person / Time
Site:	Browns Ferry
Issue date:	05/19/1975
From:	Gilleland J TENNESSEE VALLEY AUTHORITY
To:	Knuth D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
Shared Package
ML20085F006	List: ML20085F009
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8308180203
Download: ML20085F009 (2)

Text

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% !?re.,& h" May 19,1975 Mr. Donald F. Knuth, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Knuth:

BROWNS FERRY NUCLEAR PLANT UNIT 3 - REPORTABLE DEFICIENCY -

CORROSION IN MAIN STEAMLINE ISOLATION VALVE OPERATORS Initial repor' c of the subject reportable deficiency was made to B. J. Cochran, NRC-IE, Region II, on April 17, 1975. In

, compliance with paragraph 50.55(e) of 10 CFR Part 50, we submit

, the enclosed final report of the deficiency.

Very truly y,ours,

, WC J. E. 0111 eland

. Assistant Manager of Power Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 818 230 Peachtree Street, NW.

Atlanta, Georgia 30303 e

f 8308180203 750604 PDRADOCK05000g S

An Equal Opportunity Employer s.

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i-ENCLOSURE

[p. BROWS FFRRY UUCLEAR PLAUT UNIT 3

' CORROSION'IN THE MAIN'STEAMLINE ISCLATION VALVE'0PERATORS

' FINAL REPORT i

' Description of Occurrence

, During the process of replacing the seals in the main steamline isolation valve operator (FDI 169-8700-1), it was discovered that the air cylinder on the operator was severely corroded. This condition was found to exist

.for all the main steamline isolation valves (MSIV) for unit 3. A request

, s, was made to the manufacturer of the operators, Hydro-Line, to send a field I

representative to inspect the corroded cylinders. After examination of the cylinders by the Hydro-Line representative, it was concluded that the ~

corrosion was severe enough to warrant replacement of all eight cylinders.

'Cause'of Deficiency Each cylinder contained excessive moisture and rust which has led us to conclude that the cylinders were not properly stored before installation.

Safety Implications The main steamline isolation valves are part of the protection syst m of the Browns Ferry Nuclear Plant. Since the operators of all the unit 3 MSIV's were corroded, it is conceivable that a common mode failure could have occurred sometime during tne plant lifetime if the problem was not rectified.

Failure of the air cylinders would not prevent the MSIV's from closing but would prevent opening them. Since there are no design basis events that require opening the valves, they will fail in a safe condition.i '

Bovever, such a hypothetical common mode failure of all the valves at the same time would have been exceedingly remote in that the leakage needed to precipitate such a failure would have been detected before such an event  !

occurred due to required periodic testing of the MSIV's.

' Description of Corrective Action '

The corroded cylinders were replaced by new cylinders ordered from Hydro-Line, and immediately installed. on.the unit 3 EEIV'E.

Means Taken to Prevent a Recurrence The problem should not recur with the new cylinders since they vare not stored for any long period of time. Unlike the original cylinders, these were installed immediately. This completes the procurement of these cylinders for Browns Ferry.

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