ML19354D443

LER 88-028-01:on 880601,main Control Room Ventilation Sys Isolated on Channel D High Chlorine Concentration Signal. Caused by Rainwater Coming in Contact W/Chlorine Analyzer Probe.Special Event Procedure SE-2 implemented.W/891031 Ltr

ML19354D443
Person / Time
Site:	Limerick
Issue date:	10/31/1989
From:	Endriss C, Mccormick M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-88-028, LER-88-28, NUDOCS 8911090102
Download: ML19354D443 (5)

Text

.- _ _ . . - - .

i.'

Q _ . ; '. . - i 10 CFR 50.73 .

PHILADELPHIA ELECTRIC COMPANY *

@0 h- LIMERICK GENER ATING STATION

- P. O. BO X A f-SAN ATOG A, PENNSYLV ANI A 19464 (215) 3271200 axv. 2000 ,

M. J. M c co M M IC K, J... P.E.

October 31, 1989 .

Docket No. 50-352 Document Control Desk U.S. Nuclear Regulatory Commission  ;

Washington, DC. 20555

?

SUBJECT:

Licensee Event Report ,

Limerick Generating Station - Unit 1 This LER is reports an automatic actuation of the Control i Room Emergency Air Supply (CREFAS), an Engineered Safety Feature, I resulting from a chlorine concentration signal caused by rainwater contacting a chlorine analyzer probe.

Reference:

Docket No. 50-352 Report Number: 01-88-028  ;

Revision Number: 01 {

Event Date: August 17, 1988 j Report Date: October 31, 1989  :

E Facility: Limerick Generating Station i P.O. Box A, Sanatoga, PA 19464 .';

} This revised LER is being submitted due to the completion of h  :

'1

'. the modification committed.to in the original'LER. The original LER was submitted pursuant to the requirements of.10 CPR 50.73(a)(2)(iv). Changes in the revised LER are indicated by revision bar markers in the right hand margin.

l 1

Very truly yours, l t -

0 ,

JKPich cc: W. T. Russell, Administrator, Region I, USNRC T. J. Kenny, USNRC Senior Resident Inspector INPO Records Center 89.11090102 891032

{DR ADOCK 05000352PDC f

1

t as

, ter,an see 43 6 Avt 4that 465u4610ev CDhew4lso% 7 e 4,PPIOvtD OWDh0 DO OMa.

LICENSEE EVENT REPORT (LER) 8 u S ' 8' o '

..C. .t. aws n, om . t v o-a . <,, mi+

Limerick rencrating Ftntion Unit 3 0161010101 35[2 1 1 lor l 01 4 )

Control Room HVAC 1so3ation Resulting from a High Chlorine concentration Signal cn n o. A b uninenter enntarrino nn nnni m e Penh l 4vawr Datt sei te m wuwet a isi ne ron t ca ve ivi cruta eaciLititsowyotvecici -

Monies Cav Team 9tah "*[ g' h* b Q*,[,Q M;th i s, Dev S t Aft ' AC4 A Ave t f.UC hl t Nuw$ t h'S:

0l61010 1 0 1 1 i j

~ ~

0l8 1l 7 8 8 8l8 0l2l8 0l1 1l 0 3lI 8 l9 tuis atront is suewirf tp evasvawr to tal atovialwl=es os io tem 6 <c%e . e, .e 0 isioioici I i

,,,,,,,,, ee eae +eue as, t u "oot *' a miu n mio x n u.nen,o n ,no .

ITU," 08i ;7 - - - -

no a ai.ninw u n.nsi w n.nin.o

_ gt, 4 , s,.g., .j;g

~

. m..in n.oi

~~~

n n.n,im o n n.n. .n., ,,,,a, .

p n,.nsun no n,.nsn. .no, i n ace ion i a m num u ni.nanm, so ni.neno i LICIN8t t C04 tact 00m tMis 48 9 nas

%mut flitP=0%t Nyveta Carl R. Endriss, Regulatory Engineer, Limerick Generating ..la cost ,

Station 2 ,1,5 3,2,7 , ,1,2 ,0,0 CDMPktv8 0%8 Leht son tacM C0ue0=Iwt sattung pgscoittp th tuis atroat its.  !

CAVlt tvstav COMPONt%t W$ $C ][(,'((g d Cavst sv st 8 v COv*0%iNY " hj$U  %((,'[j[

i i i ! I I I I I i l i l i I  !

1 1 I I I i 1 1 I l 8 I i I ,

Su&PLluthtat pl*0a? t aptettp ttei Mo%ta caw vtan

$v99'68 04 r batt up til fift.s reawe4,p,ff,p ,vp4tr$3f04 pa r,s go au n aC, io-,, m ... . .... ., ., . . , . ,, ,,,,-,, . , n o ,

On August 17, 1988 at 1832 hours0.0212 days <br />0.509 hours <br />0.00303 weeks <br />6.97076e-4 months <br />, the main control room ventilation sytten isolated on a "D" channel high chlorine concentration *1gnal. The "B" train of the Control Room Emergency Presh Air Supply (CREFAS) system, an Engineered Safety i Feature, initiated as designed. The event occurred during severe I local thunderstorms. The high chlorine concentration signal was i caused by rainwater coming in contact with the chlorine analyzer J probe resulting in a chemical imbalance in the probe's j electrolyte. The analyzer probes are located close to the outside air intake plenum louvers. When the "D" chlorine detector spiked, operators implemented Special Event Procedure 1 SE-2 (Toxic Gas Procedure) and manually tripped the "A", "B", and i "C" chlorine isolation channels in accordance with procedures, l Proper control room isolation was verified. After the spike, f Operations personnel verified that all chlorine channels were within normal levels (less than 0.1 ppm). The isolation was reset at 1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />, and normal control room ventilation was restored. There was no chlorine intake to the main control room.

i There was no release of radioactive material to the environment as a result of this event. A modification to relocate the chlorine detection probes was implemented on August 29, 1988 to mitigate false, environmentally related, automatic control room ventilation system isolations. Additionally, a second modification designed to change the chlorine detection logic was

! completed on September 7, 1989.

I 1

_ . - . _ _ _ _ _ . . ~ _ _ _ ._. , _ _ . _ . _ _ . - - .__ _ . _ _

1. eem 342 418 huCbl&$ E4494&tDDT CDmM854sD4

'. LICENSEE EVENT REPORT ILER) TEXT CONTINUATION a==o io eve *o swee r , e o.ais a w n Teclutt esaast en , pp;at,wwwennaan ten humete ses * & D 4 IS, ma "t!.Mt' t'#.R Linierick Generating Station 11 nit 1 o o lc lc l3 l 5l 2 8 l8 0l2p 0 l1 0 l2 or 0 l4 j isr,u . ,* c, ..mn l I

)

Unit Conditions Prior to the Eventt Operating Mode 1 (Power Operation)

Reactor Power 87%

l f Description of the Events l

On August 17, 1988 at 1832 hours0.0212 days <br />0.509 hours <br />0.00303 weeks <br />6.97076e-4 months <br />, the main control roon j ventilation system isolated on a "D" channtil high chlorine .

concentration signal. The "B" train of the Control Roon l Emergency Presh Air Supply (CREFAS) system, an Engineered Safety  :

Feature, started as designed when the chlorine analyser j momentarily spiked to approximately 1.0 ppe. The isolation j occurred during severe local thunderstorms. After the isolation, control room operators implcmented Special Event Procedure SE-2 l (Toxic Gas Procedure). Operators verified that the "A", "B", and  ;

"C" chlorine detectors indicated normal levels and determined i that the "D" channel isolation signal was false. Operations  !

personnel then manually tripped the "A", "B", and "C" chlorine ,

isolation channels according to procedures to ensure complete isolation of the control room ventilation system. Proper control  !

room isolation was verified. After the spike, Operations  !

personnel verified that all four chlorine isolation channels were  ;

within normal range (less than 0.1 ppe). The isolation was reset t at 1910 hours0.0221 days <br />0.531 hours <br />0.00316 weeks <br />7.26755e-4 months <br />, and normal control room ventilation was restored.  !

The duration of the control room isolation was 38 minutes.  ;

k Consequences of the Event The main control room ventilation system tripped and isolated. -

The "B" train of the CREFAS responded as designed. The "A" train l of the CREPAS was in standby and available for operation. There l was no chlorine intake to the main control room. If actual chlorine had been detected,'as indicated by the redundant i chlorine detectors, the chlorine detection system would have responded as designed and all control room personnel would have

• donned self-contained breathing apparatus within two minutes as .

required by SE-2. There was no release of radioactive material as a result of this event.

..;..a. .

t

este ..ee an6a , , W 6 huCLt&A Eton41027 COMM'l'B'04  !

"". LICENSEE EVENT REPORT (LER) TEXT CONTINUATION emo in eve wo mo-c'e*  !

, so an sv n  !

,at.ipt y have ett vocalt hewsteag' Patet tai sta hvMest ici

,,.. .w%  :

.. a .n  !

Limerick Generating Station Unit 1 i o l6l0lol013 lSj J q8 ._

0 l 2l 8 0l1 0l3 or 0l4 ,

wt u . . m n c w mo . nn j i

I Cause of the Event:

The cause of the main control room ventilation system isolation i and initiation of the "B" train of CREFAS was rainwater coming in contact with the chlorine analyzer probe during severe local l thunderstorms. This caused a chemical imbalance in the probe's electrolyte which simulated a high chlorine condition. The probe l la located approximately one foot away from the outside air r intake louvers of the Control Enclosure intake plenum making it  !

susceptible to moisture intrusion during inclement weather conditions. .

Corrective Actions:

L r

Control Room personnel implemented Special Lvent Procedure SE-2  !

(Toxic Gas Procedure) lamediately following the isolation. i Operations personnel then verified that the "A", "B", and "C" chlorine detectors indicated normal levels and determined that '

the "D" channel isolation signal was false. Operations personnel then manually tripped the "A", "B", and "C" chlorine isolation l channels, in accordance with System P:'ocedure S*/8.0.B - l j " Verification of Control Room HVAC Response to a Control Room i Isolation Signal", to ensure complete isolation of the main control room ventilation system as directed by SE-2. After the '

spike, Operations personnel verified that the chlorine detector

! channels ("A", "B", "C", and "D") indicated chlorine ,

l concentration levels were within normal levels (less than 0.1 ppm). The main control room ventilation system isolation was reset and normal control room ventilation was restored at 1910 -

hours.

1

pg.m -.

l l

- ~ _ - - - _ _ ~ , _ - _ _ - _ _ _ . - . , . __ __._ __ _ _ _ - . _ - - - _

mac eeen b. V 4 avvChina ElSub&to37 Co==@one anaosso eve no w-o*

LICENSEE EVENT i4EPORT (LER) TEXT CONTINUATION

- =,ines ev n

. .c .v t , ... n , , gw it =vena y t i . .,vo. . .., ..u .

l u .' I d hui . i t'#.t{

Limerich Generating Station Unit 1 o s to l0 o 3 l $l 2 8 (8 -

0l2l8 0l1 0 l4 of 0 l4 em u ., ,. ..e w ,=u.,m, Actions 'taken to Prevent Recurrences Two modifications to CREFAS were implemented to prevent spurious isolation of the Main Control Room (MCR) ventilation system. The first modification consisted of moving the analyser probes away from the outside air louvers. This new location provides better protection for the analyser probes from rainwater and dirt.

Since the implementation of this modification on August 28, 1988, there have been no spurious environmentally related chlorine detection system isolations of the MCR ventilation system. The second modification changed the chlorine detection system logic from a "one out of one taken once" to a "two out two taken once" configuration. With this change, a single spurious chlorine ,

isolation channel signal will not result in a MCR ventilation system isolation. This modification will prevent any spurious environmentally related chlorine detection system isolations of the NCR due to a single false isolation signal or a single detector probe malfunction. This modification was completed on September 7, 1989.

EIIS Codest  ;!

Control Room Ventilation - (VI)

Analyzer - (AE)

CREFAS - (VI)

Previous Similar Occurrences Limerick LERs 86-46, 87-03, 87-06, 87-09,37-051, 88-014,88-018, 88-021,88-026,.and 88-027 reported CREFAS actuations resulting from false "C" or "D" high chlorine concentration signal during rainy weather conditions.

Tracking Codes (C) - Ex'ternal Chuse (B99) - Design Deficiency f 0Ans assa