ML20027A180

LER 78-055/01T-0:on 780930,HPCI Turbine Tripped on Low Pump Suction Pressure of 11.5 Psig.Caused by Drift of Pressure Switch PS2-2360

ML20027A180
Person / Time
Site:	Dresden
Issue date:	10/13/1978
From:	Lindberg C COMMONWEALTH EDISON CO.
To:
Shared Package
ML17173A290	List: ML17173A289 ML20027A180
References
LER-78-055-01T, LER-78-55-1T, NUDOCS 7810200097
Download: ML20027A180 (2)

Text

I

' d LICENSEE EVENT REPORT i

c0NTROL stock: l 8

] l l l l l@

6 (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATl!N) l o l319 l l I UCENSEE lIL l DCOOE l R lS14 l 2:5 l@l 0l Ol -luCENSE Ol NUMBER 010l O! 0l -I 0l25 0l@l4 26 l1 l1 TYPE LaCENSE l1l1l@lJO l

57 CAT 58 l@

Con T. - '

!o1il 3

,"c' l60L l@l0 l 5 l0 l010 l2 l 3 l7 @l019 l3 l0 l 7l ra8 @l Il REPORT 0l Il3DATsl7 l8 80l@

6d 69 EVENT DATE 75 8 j 63

• DOCKET NUMB E R EVENT DESCRIPTION AND PROSABLE CONSEQUENCES h o12l l While performing DOS 2300-3 (HPCI Turbine Guarterly Surv.) the HPCI turbine tripped l

!Olal I on low pump suction pressure of 11.5 psig which exceeds the Dresden setpoint of 9.4 1 ioi4l l in. Hg vacuum increasing. Safety significance was reduced since redundant Isolation l

o,3; l Condenser and Auto Depressurization Systems were operable. No previous similar 1

! O l6 l l events at Dresden. l

.oi7II I n el I I 80 8 9 E CO E S SC E CO.*.tPONENT CODE SLBC DE SU E a19l d 9 l S lF lh l El@ l Elh lIl NI S l T l R l U lh l El@ lZ lh to in 12 13 18 19 20 SE QUENTI AL CCCU R R ENCE REPORT REVISION gggjpg j (VSNT YEAR RE* ORT NO. CODE TYPE N O.

h REPORT l7l8l l-l l01515l l/! l011 l lT l l-l l0 l

_ 21 22 23 24 . ^6 27 28 29 JO 31 J2

• TAK f AL Cr CNP NT E 40VRS SS IT F O'R 8. SUPPLt MAN AC RER trLJ@LIJ@ Id @ !JSz l@ !OlninInl 27 ,o Lt.]@

41 LtJ@ Laj@ lul21,Isl@

33 54 35 42 43 44 47 CAUSE DE::CRIPTION AND CCRRECTIVE ACTIONS h l i 1 o l l The cause was attributable to instrument drif t of pressure switch PS 2360. The 1

i iil l switch was recalibrated to trip at -9.4" Hg increasine. The switch will ha ch ac1c arl 1

a l in two months to ensure its continued acceptability. I

1 131 1 I*

~

l i 141 1 l 8 9 80 ST L  % POWER OTHE R STATUS DIS O Y DISCOVERY DESCRIPTION 31  ! $ I lE l@ l 0 l 9 l 2 l@l NA l lBl@l Surveillance Testine l ACTivtTY CONTENT RELEASED OF RELEASE AMOUNT OF ACTivlTY LOCATION OP RELEASE NA l l NA l

' ' 168 l9 l Z l h l10Z*l@l 11 44 45 80 PERSONNEL EXPOSURES NUMBER d i l 7 l l 0 l 0 l 0 l@lTYPE l @l DESCRIPTION _

l 1

' ' ,E R so~~ El',~2uLS

NUMBER OESCRIPTION

i i a l 10 l 0 l o l@l NA l 8 9 . 11 12 80 LOSS OF OR D AMAGE TO F ACILITY TYPE DESCRIP TION I vi l_yj@l yA . l 4 9 10 60 r32ct DE CRIPTION i

I o I l.N_jhl NA l lllllllI!IIIl 1 '

=.29 10 68 69 80. ;

h ppep ggyp

'. M WW r-::.~ Q

. . ,N 03 eOO$7 flAMF op Carl Lindber3 PHON E:

F289 a a, ,

ATTAbC4ENTTOLICENSEEEVENTREPORT 78-055/01T-0 COMMONWEALTH EDISON COMPANY (CWE)

DRESDEN UNIT-2 (ILDRS-2)

DOCKET #050-237 While conducting the HPCI Turbine Quarterly Surveillance DOS 2300-3, the HPCI Turbine tripped on low pump suction pressure sensed by pressure switch PS-2-2360. The switch tripped at 11.5 psig which is considerably above the Dresden setpoint of 9.4" Hg vacuum increasing. The safety significance of the event was reduced since the redundant Isolation Condenser and Automa, tic Depressurization Systems were operable.

(

In the surveillance procedure, normally closed MO valves 2-2301-14

-(Flow to Tor'us), 2-2301-10 (Flow to 2/3B Contaminated Condensate Storage Tank), and 2-2301-49 (HPCI bypass line) are all opened and the HPCI turbine is started against little backpressure. Using a temporary procedure change, valve 2301-10 was closed to restrict the pumps discharge and HPCI started normally. Valve'2301-10 was subsequently throttled and proper flows and pressures were obtained to satisfactorily demonstrate operability in accordance with the surveillance requirements.

However, af ter subsequent management review on the next normal working day, it was concluded that HPCI might not have been operational under all accident conditions and should have been reported inoperable in accordance with Technical Specifications 6.6.B.1.e.

The cause of the trip was insernment drift of PS2-2360. The switch was '

(

1 recalibrated to trip at 9.4 inches Hg vacuum increasing. These switches have been calibrated each refueling outage in the past, and a review of records indicates no unusual tendency for excessive drif ting of the switch setpoints. The switch will be checked in two months to ensure its continued acceptability.

4

.s . s.v . _ J