ML20084T496

Ro:On 721111,during MSIV Timing Surveillance Testing,Msiv 3-203-1B Had Closure Time Faster than Tech Spec Limits. Caused by Slight Oil Leak in Valve Fitting.Fitting Tightened,Oil Added & Valve Retimed

ML20084T496
Person / Time
Site:	Dresden
Issue date:	12/08/1972
From:	Worden W COMMONWEALTH EDISON CO.
To:	Giambusso A US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084T499	List: ML20084T496
References
NUDOCS 8306230230
Download: ML20084T496 (3)

Text

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o Commonwealth Edison Company l 72 WEST ADAMS STREET

• C H I C A G O. ILLINOIS Amen Eselp een j cost orrecs som ist

• c en i c a c o, o t t i n o i s s o s, o l Dresden Nuclear Power Station l R. R. #1 l Morris, Illinois 60450 December 8, 1972 C g ,

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50-249 p

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59W Hr. A. Giambusso -

DEC L. , , . . e

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Deputy Director for Reactor Projects g 414rck -

Directorate of Licensing u CMal.

U. S. Atomic Energy Commission Washington, D. C. 20545

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SUBJECT:

LICENSE DPR-25, DRESDEN NUCLEAR POWER STATION, UNIT #3, SECTION 6.6.C.1 0F THE TECHNICAL SPECIFICATIONS,

Dear Mr. Giambusso:

This is to report a condition relating to the operation of the station, when during surveillance testing, main sesam isolation va'.ve (MSIV) 3-203-1B was found to have a closure time of 2.1 seconds, which is outside the limits specified in the Technical Specifications.

PROBLEM AND INVESTICATION At 0530, November 11, 1972, with the reactor at a power

]OOP level of 1113 MWe, quarterly MSIV timing surveillance was being conducted. During these tests, it was discovered that MSIV 3-203-1B fk)<

had a closure time of 2.1 seconds, faster than theyecond to 5 second limits specified in the Technical Specifications (Table 3.7.1). Both valves in the "b" steam line were promptly closed in accordance with f section 3.7.2 of the Technical Specifications, and maintained in that condition until a subsequent shutdown. The MSIV's on the other three steam lines had closure times within the 3 second to 5 second limits.

The limits specified on fast closure of the MSIV's are intended to prevent a rapid reactor isolation, and subsequent rapid reactor pressurization and resulting relief valve operation. Closure of one MSIV in 2 seconds instead of 3 seconds does not significantly increase the pressure spike or the potential for relief valve operation.

Additionally, any pressure transient from the fast closure of one MSIV would be " softened" by the slower MSIV closure on the other three lines.

Consequently, it is concluded that the fast ciceure of the 3-203-1B MSIV was of no safety significance.

G306230230 721200 PDR ADOCK 05000249 0

PDR C0PY SEgr nEGION ^

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, Mr. A. CiambussaO ,

Dezember 8, 1972 CORRECTIVE ACTION '

On November 19, 1972, during a subsequent plant shutdown, MSIV 3-203-1B was inspected and found to have a slight oil leak in a fitting (see attached figure). This fitting is in the valve's hydraulic speed j

control system. On loss of oil, the speed control system causes the valve  ;

to closa faster. The fitting probably leaked due to insufficient tighten b ]

ing during installation. The slight leakage eventually resulted in j sufficient loss of oil to affect closure time.

l The fitting was tightened, oil added, and the valve retimed. -

The valve operated satisfactority and the 2 valves on "B" steam line were opened for startup. This problem is considered a one time occurrence and no further action is planned at this time.

Sincerely,

). . hp VN fW.P.Werden Superintendent

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