ML19340C265

Updated LER 80-050/03X-3:on 800717,0804,29 & 1014,steam Driven Emergency Feedwater Pump 2P7A Turbine Driver 2K3 Tripped on Overspeed.Caused by design-related Problem.Pump Removed from Svc for Design Mods

ML19340C265
Person / Time
Site:	Arkansas Nuclear
Issue date:	11/07/1980
From:	Shively C ARKANSAS POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19340C264	List: ML19340C263 ML19340C265
References
LER-80-050-03X, LER-80-50-3X, NUDOCS 8011140386
Download: ML19340C265 (2)

Text

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r UPDATE REPORT - PREVIOUS REPORT DATE 9/29/80

! NRC FORM 366 U. S. NUCLE AR REGULATORY COMMIS$ lose LICENSEE EVENT REPORT EXHIBIT A j

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EVENT DESCRIPTION AND P90BADLE CONSEQUENCES h rdTil I During Mode 1 operation, the steam driven emergency feedwater pumo, 2P7A,i  ;

io ni i turbine driver, 2K3, tripped on overspeed on the following dated: 7/17/801, io n i i 8/4/80, 8/29/80 and 10/14/80._ The electric driven pump, 2P7B, and I o s i associated valves were verified operable. This occurrence is similar to I o s l LER's: 50-368/79-055,79-072, 79-081.79-104. 80-022. and 80-036. I o , i Reportable per T.S. 6.9.1.9.b. l I

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33 el eJ as er CAUSE DESCRIPTION AND CORREC f1VE ACTIONS 27 i o l Cause of overspeeds is believed to be design related. EFW pump, 2P7A, i i i was removed from service for design modifications on 10/17/80, entering i See attached for further data, iTTF1i Action Statement T. S. 3.7.1.2. i GII] I I i I i

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! o ATTACHMENT TO LER 50-36P/80-050 REV. 3

! The exact cause for.the overspeed trips could not be determined; however, ~they _are believed to be design related. o0n 10/17/80, a design-change was . implemented-that replaced _the EGR sump and changed-out the control oil tubing. The design specification called for 3/8" 0.D. tubing with a 0.035" wall thickness. The tubing that

! was originally ir,'.alled had a 3/8" .0.D. and 0.065" wall thickness.

This difference .c wall thickness created approximately a 50%

reduction in available flow area for the control oil. The newly f installed tubing is 3/8" .0.D. and 0.035" wall thickness.

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A testing program has been implemented to obtain detailed operating data that would verify pump / turbine reliability and assist with future failure analysis if this last design change has not fixed the overspeed trip nroblems. The new test program is designed to start th.e pump and record pertinent operating data at the following time intervals.

i 1. At 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> intervals for 3 days.

2. At 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> intervals for 4 days.

3. At 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> intervals for 6 days.

, 4. At 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> intervals for 8 days.

5. At 1 week intervals for 2 weeks.

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6. At 2 week intervals for 1 month.

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Finally, the testing interval will be at a monthly frequency. In i the past, the overspeed problems seemed to be more frequent if idle .

periods greater than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> had 11apsed between pump starts. This i

new testing program should indicatt what effect the design change

has on pump reliability following long idle times. The testing program, as of 11/4/80, is in the 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> interval period and no i failures have occurred.

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