05000278/LER-1990-007

LER 90-007-00:on 900620,RWCU Isolated While Pressurizing Sys Following Isolation Valve Insp.Caused by Design Weakness. Design of Instrumentation Reviewed & Procedural Controls enhanced.W/900719 Ltr

ML20055G606
Person / Time
Site:	Peach Bottom
Issue date:	07/18/1990
From:	Fray J, Fulvio A PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-007-03, LER-90-7-3, NUDOCS 9007230366
Download: ML20055G606 (4)

LER-2090-007,

Event date:
Report date:
2782090007R00 - NRC Website

text

r

, CCN-90-l'4i36 -

s :,

PHILADELPHIA ELECTRIC COMPANY:

PEACil IKyrlOM A1DMIC POWER STATION :

R. D.1, Box 208 Delta, Pennsylvania 17314 -

i 6 :- : re.aca sonou-tus rowns or excittesca (717) 456-7014-July 19, 1990 Docket No. 50-278 Document-Control Desk

.U. S. Nuclear. Regulatory Commission

-Washington, DC 20555

SUBJECT:

-L Licensee Event Report =

Peach Bottom Atomic Power Station --Unit 3 This LER concerns a Reactor Water Cleanup Isolation during pressurization

'of system following isolation valve inspection.

Reference:

- Docket No. 50-278

' Report Number:- 3-90-007

-Revision-Number: 00 Event Date: 06/20/90 Report Date:- 07/19/90 . .

Facility: Peach Bottom Atomic Power Station RD 1. Box'208, Delta, PA 17314 This LER is being submitted pursuant to the requirements of 10 CFR 50.73(a)(2)(iv).

Sincerely, f) lant Manager cc: J. J. Lyash, USNRC Senior Resident Inspector T. T. Martin, USNRC, Region I 9007230366 900718 gDR ADOCK 05000278 PDC Ut

NRC for2 ate U $ NUCLSCO 7.EOULATO.,Y COMutsolON APJ ROYED OM8 LO 3160 0104 -'

9 ?' . LICENSEE EVENT REPORT (LER)- < = P'a's s '8'

7 ACILITY N AME (1) DOCKE T NUMBER 13l FAGE G Peach Bottom Atomic Power Station - Unit 3 0 l 5 l 010 l 01217 l 8 1 lod o l3 Reactor _Wh'er Cleanup Isolation During Pressurization of System Following isolation valve Inspection EVINT DATE 486 LER NUMB 3R lol REPORY DAtt 171 OTHER f ACititlES INVOLVED (81 MONTH DAY YEAR Y(AR , M MONTM DAY TEAR * *CILIT V N Aur s DOCILE T NUM6tRiti 015101010 1 l- I

~ ~

ol6 2l 0 9 0 9 l0 o l ol7 ol0 ol 7 1l9 9l 0 0l510 tol0l l l OPE R ATING THis REPORT is $UsMitTt0 PURSUANT TO THE RioutREMENTS 07 to CFR 5 (Casta eae er more of ,a* foneamas (111

1. I I'l N 20 40214) 20 40stel X 50 7JieluH'=1 73 tilti to 406teH1HH 50 38tsHl) 60 734eH2Het 73.711st 4i0 1Io I o 20 asi.Ht He s0 nt.iui s033mH2Hai

_ g,H5, s7Te"O'N'7/-

20 406teHIH66 1 60.73ieH2 H4 60.731 ell 2ituutHA) ' Jessa) 20 406teH1H6vl 60 73deH2Hw) 50 73tel(2HvslHiga 20 406tell1 Hv) 50.73mH2H.6.1 to.731s (2Hal LICENSEI CONT ACT POR TH18 LIR 612)

NAME TELEPHONt NUM8tR AR6 A COOg A. A. Fulvio, Regulatory Engineer 7 1117 415161-17lo 1114 COMPLEf t ONE LINE FOR E ACH COMPONENT F AILURE DESCRISED IN THis MtPORf 113 HE'ORTAa t

~

CAUst sysTIM . COMPONENT Myyc. CAust sv$7EM COMPONENT [ RfC 'R 5 l l I I l l l l 1 1 I l 1 1 1 I I I I I -l l I I I I I I

$UPPLEMENT AL REPORT EXPECitD tt46 MONTM DAY YEAR SutMissaON 4ES !!! vos complete EXPfCTE0 $UOMtsstON DATEI NO l l l

..:T R AC v m,,,,, ,, um .-eu e . .,..-+, ,.n w. . ,,- ...., n ei On June 20, 1990,-at 12:12 p.m., with the Unit at 100% power, the Reactor Water Cleanup (RWCU) system-isolated while pressurizing the system following inspection.

.It is believed that as the system was being placed in service, flashing occurred when the outboard valve was opened. Flashing of the water into steam would have caused a high flow rate to be sensed, as additional water was drawn into the system.

The root cause is believed to be a design weakness. Although the operator exercised l proper caution while opening.the outboard valve, the system isolated on high flow.

L The existing design of the high flow isolation instrumentation does not allow for L short duration changes in flow conditions when placing the system in service. The l- design of the high flow instrumentation will be reviewed. Procedural controls will be enhanced to warn the operator of the potential high flow condition when placing t .the RWCU system in service.

1

'A copv of the Event Investigation Report will be distributed to all licensed nm sonnel for informational purposes. No actual safety consequences occurred as a result of this event.

. There are two previous similar LERs.

g,.,. m. _ ,

. - . . .. . - ~

( I I' AfibC Perm SBDA . 4 U.S. NUCLE A3 [E!ULATORY COase#80860N R' "

LICENSEE EVENT REPORT (LEH) TEXT CONTINUATI'JN maoveo oue no mo-oios o pi . s t. Expines: saio l musuty manna n, , oocusi muasssa (28 - Len wunseen sei PAos (si 4'- ,

,sove m A6 neve.ow JP;ach Bottom Atomic Power Station "* ""

LUnit'3; '

q 0 l5 l0 l0 l0 l 2l7 l8 9l0 -

ol o l7 -

o lo ol2 oF o l3 [

vent a . = ,w we r.-amm nm j

Requirements:for the Report:

This report is

required per 10 CFR 50.73(a)(2)(iv) due to automatic' actuation of an

'i

/Engi_neered Safety Feature.(ESF).

Un'it Conditions at Time of Discovery: ,

i

. Unit 13 was tin the RUN: mode' at 100% of rated thermal reactor power'. t

- LThere were no systems, structures, or components that were inoperable that-icontr_ibuted to'this event.

l. Onscription of Event.

p ,

IL l 0n ' June - 20, ~ 1990,_. at :12:12 p.m. , with .the Unit at 100% power, the Primary 1

' Containment Isolation 3System (PCIS).(Ells:JM) isolated the Reactor _ Water Cleanup  !

.(RWCU).(Ells:CE) system while pressurizing the system'following inspection. The RWCU-

. system had been removed 1 from service in' order to verify the-extent lof a packing leak-l" I on MO-3-12-18 "RWCU Outboard Isolation' Valve" (Ells:ISV). _After it was determined P ,that the leak.was not'significant enough to require immediate' maintenance, it was

• decided that RWCU could-be put back in service, y

~

g , The system depressurized to approximately 300 psig with temperature at.450; degrees'F '

while it-was out of service.- Since the system had only been out of service _for u

( approximately'two hours and-had_not been drained, the:0perator entered the RWCU 1

startup procedure at the: appropriate step for these: conditions.-

u Being' aware of. a:RWCU < isolation which occurred on Unit 2 on -thelprevlous shif t (LER -

2-90-14) the OperatorJ(Utility, Licensed) was using extra caution in opening the RWCU suction valves. : M0-3-12-15 "RWCU Inboard-Isolation Valve" was " bumped" open over a j

five minute; period to pressurize up to the outboard isolation valve. M0-3-12-18 was

. then'" bumped" open to pressurize the rest of the system while monitoring system: H

pressure. A. caution precedes these steps in the procedure to instruct the operator

' to'. slowly open the inboard and. outboard valves to minimize thermal and pressure l

shock.:

Even:though the outboard valve was bumped for only two seconds in the open direction, :l the RWCU system isolated from'a high flow signal. Actions taken by the Operator were j 1 Lconsistent.with prior practice and procedure, q

, , :After confirmation that'PCIS responded as designed, the RWCU system was placed back q

.in service at.2:15 p.m. without further incident.

Cau'se'of-Event- l llt is believed.that with the pressure Of 300 psig and temperature of 450 degrees F 1 w when the system was being placed in service, flashing occurred when the outboard valveiwas opened. Flashing of the water into steam would have caused a high flow j rate to be sensed, as additional water was drawn into the system.

E

-y

N ORM 384A - 'U.S. CPoi 1988-S N-589,000 N w

f.'  ;. >

R

'd IIRC perm MSA ;

' U.S. NUCLli2 5.tIULATORY C0sAMam:0N I LICENSEE EVENT HEPORT (LER) TEXT lCONTINUAT13N uezovio ome No. mo-om

[. it.PIRES; $/31/N W4LITV NAME til . . DOCKET NutetR (2) LIR NUMSER It) PA05 (3)

Phach Bottom Atomib_ Power Station-

" "'N 0 l5 l0 l0 l0 l2 l7 l8 9ln -

ol0l7 -

olo o l3 oF 0 l3 ran u, . M ,w =ac % am4 w r.n The root cause'is' believed.to be a design weakness.. Although 'the operator' exercised Lproper caution i.n opening the outboard valve, the system isolated on high flow. The'-

. existing design of the high flow' isolation instrumentation does not allow for short duration changes.in flow conditions when placing the system in service.

Analysis of Event No' actual safety consequences occurred as a result of this event.

This event is. considered to be of minimal safety significance. RWCU was out'of service for a total of,.approximately_four hours, which did not present a reactor water chemistry concern. This-isolation caused RWCU to be isolated for two hours longer =than planned. j k ' Corrective Actions a The design of the RWCU high flow instrumentation will be reviewed. Procedural Jcontrols will be enhanced to warn the' operator of the potential high flow condition a while placing'the RWCU system in service.

Al copy of the Event Investigation Report'will be distributed to all licensed

~

! personnel for informational purposec.

Previous'Similar~ Events ]

Two previous similar LERs (LER'2-85-18 and LER 2-90-14) have been identified. Both w2re similar in that they dealt with a RWCU isolation due to opening of a valve. The corrective actions taken;in LER 2-85-18 did not prevent this event because

they dealt 1 with operator-actions. LER 2-90-14 happened the same day as this LER so corrective j actions could not have been expected'to prevent recurrence of this' event, j l

i l-L i

v

-[,

l l

l=

li NRC FORM 366A *u.s. CP0s 199B- H0-189,00070 I. ' 19 SJ) - i

-. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ . _ _ _ _ _ - _ _ __