ML20029B069

LER 91-002-00:on 910203,partial Outboard Group 2 Primary Containment Isolation Sys Isolation Signal Resulted in Closure of Containment Isolation Valves.Caused by Failed Relay Coil.Coil replaced.W/910301 Ltr

ML20029B069
Person / Time
Site:	Hatch
Issue date:	03/05/1991
From:	Hairston W, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-1504, LER-91-002-03, LER-91-2-3, NUDOCS 9103050342
Download: ML20029B069 (7)

Text

,

Gog a Fht Comm,,-

3D Pc:tma,t A.vaue Aha't'.tt Gtio'g a 30D0

• c are d'a4 L;'6 31ft5

. Ici M,ung Aact%s AO thwf fit st, Ce% r Pd4* Jy Post Ot* ce Ba,1:45

{Omviyrim Ai3pyy 35;Tt iewone PO5 fe 5!.81 t> u s .-: % .n ,,1c.*

W. Q. Hairston, IH

, Sena V 0: hen.:1ent nso.w omeons HL-1504 001280 March 1. 1991 U.S. Nuclear Regulatory Commission ATIN: Docuuent Control Desk Washington, D.C. 20555 PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57 NPF-5 LICENSEE EVENT REPORT COMPONENT FAILURE AND PERSONNFL ERROR RESUtT IN UNPLANNED ESF ACTUATID!i Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(iv), Georgia Power Company is submitting the enclosed licensee Event Report (LLR) concerning a component failure and personnel error which resulted in ESF actuations. This event occurred at Plant Hatch - Units 1 and 2.

SincereJy, f, , Y fick W. G. Hairsto , 111 JKB/cr

Enclosure:

LER 50-321/1991-002 c: (See next p, age.)

9103050342 910305 \ s POR ADOCK 05000321 \

s PDR i .i

CC01,4!s'tI\MelAL.

U.S. Nuclear Regulatory Comission March 1, 1991 Page Two c: Georaia Powar_ Company Mr. H. L. Sumner, General Manager - Nuclear Plant Mr. J. D. Heidt, Manager Engineering and Licensing - Hatch NORMS U.S. Nuclear Reculatory_CILmmission. Wuhington D.C.

Mr. K. Jabbour, Licensing Project Manager - Hatch Whcjfttt Regulatory Commission. Reaion iI Mr. S. D. Ebneter, Regional Administrator Mr. L. D. Wert, Senior Resident inspector - Hatch 4

I i

4

-,w - - ,e, ,,,, ,

~,r-r-- -

, - , -y .- - y

'a m u.s. m- - _g

- c------

mgw.viss i

l . LICENSEE EVENT REPORT (LER)

_ m- . m -m

_m - n l i PlWR IIA 1DI,~ (NIT 1 05000321 1 yl$-

i  ?!?bs (4)

I COMPONDU Fall >URE AND PER50tNEL ERROR RESULT IN INPI#NED ESP ACI1]ATION WYttPT (Ats M ) Lak MBISER (6) tarot? MT (7) ofMsR F ACli.1Tiss 11tYoLVsD (0) ,

"WW75 CAT isAR TEAR ss9 MNI 8:V .cogrra tat y gAk FActLgry nAnss Locust maast(s) f

Pl## llAIQl, LNIT 2 05000366 J 02 03 91 91 002 00 03 05 91 05000

, , , , . was atroet is sumunso ruasuant to ne asovissnsen or to cra un MDE O l 1 A 60.13fel(2)(iv)

' 20. 4 0 2 (t.) _ 20.40l(c). 73. 71 (l> )

Pouse 20.406te)(1)(1) 50.36tc)(3) 50.7)(e)(2t(v) 73.71(c)

~

L8v*6 100 20.aotte n t n u t 20.405(a) O)(111)

[ no.36(en2)60.73(e H 2 ) M )

60.13 (e H 2 H vu t 60.73(en2)(viliHA) onsa (specity in Atiettut below)  ;

y _

4

~

20 405(a)M)(iv) ~

50.13 (s H 2 H11 ) ~

60.73(a)(3)(viill(s) l 20.40l(eld)(v) $0.73(el(21(iii) 50.73(el(3)(al Lacsmass coertAct ron inis Lam flD) aans . nosenous meines  ;

usa cow STEVD4 B. TIPPS, MANAGER NUCIIAR SAIT!T AND COMPLIANCE, ilA1UI 912 367-7851 cOJEr!.sts 09: Lips Fok sAcIl PA1LUts (*scRADsp 1R THis ksPoRT (13) 2 cAucs se n se conrosser g',',AC- gg,, cAuss erstes enneowser 8gr,Ac- gig,,

X B il RLY GOBO Y sutrusseertAL murost sars'tso 04 -

nouTu tar isAm e

" punnassion 8273 O S I

~~} TasOf yea, complete marscTap sutwnssics tats) ~]y no  ;

Amstmact (16)

On 2/3/91 at approximately 0420 CST, Unit 1 and Unit 2 vere in the Run mode at an approximate power level of 2436 CHVT (approximately 100% rated thermal pover). At that time, a partial, outboard Group 2 Primary Containment-1 solation

- System (PCIS, EIIS Code JM)-isolation signal was generated resulting in closure of some outboard Group 2 Primary Containment Isolation Valves (PCIVs, EIIS Code

JM).' This, in turn, resulted in the isolation of the Unit 2 Ilydrogen and oxygen Analyzer (EIIS Code IK) and Fisslon Products Nonitoring (FPH, EIIS Code IK) systems. The isolation signal occurred due to a failed relay. A second ESF actuation occurred during the replacement of the failed relay. A relay apparently was bumped resulting in actuation of the "B" trains of the Unit 1 and Unit 2 Standby Gas Treatment (SBGT, EIIS Code Bil) systems, isolation of the Unit I and Unit 2 Secondary Containments, and isolation of additional outboard Group 2-PCIVs.

The cause of the first event was component failure. The coil in relay 1C61-K24 -

failed, actuating the isolation logic for some of the outboard Group 2 PCIVs per design. The cause of the second event was personnel error. A plant electrician, while replacing relay IC61-K24, apparently bumped nearby relay .

IC61-K79. This actuated the initiation logic for the "B" tr: ins or both units' SBGT systems, and the isolation logic for both units' Secondary Containments and additional outboard Group 2 PCIVs.

Corrective actions for this event included replacing the failed relay and counceling involved personnel.

- . - ._.-,m--,-,--.m.m.,. .m~.m,.m., ..,mm,,.-m.._m--,...,e__., _#,.m ,,._me.-_...,.m.,,.%...___., ,,,,,,m..-. -.--.r-m,e

~

1

. n . smu, v.s. o . _m - - - -

_ sus

_ sum

== mgm.

] [g)

twit.tn mas m ionn massa m osa m mass m aus m !

taAk see mm key 1

Pl#r RA'!UI. tNIT 1 05000321 91 002 00 2 0F 5 esa '

u PLANT AND SYSTEH IDENTIFICATION

General Electric - Boiling Vater Beactot Energy Industry Identification System codes are identified in the text as (EIIS Code XX).

SUMMARY

OF EVENT On 2/3/91 at approximately 0420 CST, Unit 1 and Unit 2 vere in the Run mode at an approximate power level of 2436 CMVT (approximately 100% rated thermal pover). At that time, a partial, outboard Grouc 2 Primary Containment Isolation System (PCIS, E115 Code JM) isolation signal was generated resulting in closure of some outboard Group 2 Primary Containment Isolation Valves (PCIVs, EIIS Code  !

JM). This, in turn, resulted in the isolation of the Unit 2 Ilydrogen and Oxygen

• i Analyzer (EIIS Code IK) and ilssion Products Monitoring (FPM, E11S Code IK) systems. The isolation signal occurred due to a failed relay. A second ESF actuation occurred during the replacement of the failed relay. A relay appatently was bumped.resulting in actuation of the "B" trains of the Unit 1 and Unit 2 Standby Gas Treatment (SBGT, EIIS Code BII) systems, isolation of the Unit 1 and Unit 2 Secondary Containments, and isolation of additionni outboard Group 2 PCIVs.

The cause of the first event was component failure. The coil in relay 1C61-K24  ;

-failed, actuating the isolation logic for some of the outboard Group 2 PCIVs per  ;

design. The cause of the second event was personnel error. A plant ,

electrician, while replacing relay IC61-K24, apparently bumped nearby relay i 1C61-K79. This actuated the initiation logic for the "D" trains of both units'  !

SBGT systems, and the isolation logic for both units' Secondary Containments and ,

additional outboard Group 2 PCIVs.

Corrective actions for this event included replacing the failed relay and counseling involved personnel.

DESCRIPTION OF EVENT on 2/3/91 at approximately 0420 CSf, a partial, outboard Group 2 PCIS isolation signal was received and the outboard Group 2 PCIVs in the Hydrogen and oxygen Analyzer and FFH syutens isolated as per design. No activities vete in progress

which might have resulted in these actions nor vere-any system logie netuation signals (reactor vater lov level or dryvell high pressure) present.. Operations

~

-personnel initiated 1.imiting Condition for Operation (LCO) 1-91-50 on the FPH-system and LC0 1-91-51 on the Hydrogen and oxygen Analyzer system per Unit 1 Technical Specifications sections 3.6.G.3.c and 3.7.A.6.c. An investigation of the unexpected-isolatinn signal vas initiated.

At approximately 0525 CST, plant electricians found an open (failed) coil in relay IC61-K24. The failed coil caused the relay to go to its designed, fail-safe, de-energiaed position. Since this relay is in the PCIS trip logic, a partial, outboard Gsoup 2 PCIS isolation signal vas generated per design. The normally open outboard Group 2 PCIVs in the Hydrogen and Oxygen Analyzer and FPM systems-closed, isolating these systems.

t 6

7 .

uc a g gr m rActun mas m sceast musess m t.se owesa m rAos ni tsAn aso aun stav Pl#ff HA101. INIT 1 05000321 91 002 00 3 0F 5 vart

The electricians proceeded to replace the coil in relay 1C61-K24 per Haintenance Vork Order (MVO) 1-91-551. At approximately 0755 CST, while the electricians were replacing the relay, the "B" trains of the Unit 1 and Unit 2 SBGT systems actuated, the Unit 1 and Unit 2 secondary Containments isolated, i.e., the Reactor Buildings and Refueling Floor normal ventilation systems (Ells Code VA) fans tripped and dampets isolated, and additional outboard Group 2 PCIVs isointed. Apparently, while replacing relay IC61-K24, an electrician inadvertently bumped relay IC61-K79, which is in close proximity to relay 1061-K24 an panel 1H11-P623.- Bumping relay IC61-K79 caused some or all of its contacts to change position momentarily. This resulted in downstream relay IC61-K75 de-energizing per design. Relay 1C61-K75 is in the actuation logic for the "B" trains of the SBGT systems, the isolation logic for the Secondary Containments, and the isolation _ logic for additional outboard Group 2 PCIVs.

These systems responded per design.

At approxfmately 0855 CST, the electricians completed the replacement of the coil in relay 1C61-K24 Operations personnel reset the PCIS isolation signals, restored the Reactor Buildings and Refueling Floor ventilation systems to normal service, returned the "B" trains of the Unit 1 and Unit 2 SBGT systems to the auto standby condition, and opened the outboard Group 2 PCIVs which had closed.

At approximately 1010 CST, after verifying the Hydrogen and Oxygen Analyzer and FpH systems vere operating properly, Operations personnel terminated LCOs 1-91-50 and 1-91-51.

CAUSE OF THE EVENT The cause of the first event was component failure. The coil in relay 1C61-K24 failed, actuating the isolation logic for some of the outboard Group 2 PCIVs per design. This-included the logic to the PCIVs in the Hydrogen and Oxygen Analyzer and FPH systems.

The cause of the second event was personnel error.- A plant electrician, while replacing relay 1C61-K24, apparently bumped nearby relay IC61-K79. This actuated the initiation logic for the "B" trains of both units' EBGT systems, and the isolation logic for both units' Secondary Containments and additional outboard Group 2 PCIVs.

REPORTABILITY ANALYSIS AND SAFETY ASSESSHENT This event is reportable per 10 CFR 50.73(a)(2)(iv) because unplanned actuations

, of Engineered Safety Features (ESFs) occurred. Specifically, the "B" trains of

, the Unit I and Unit 2 SBGT systems automatically started, the Unit I and Unit 2 Secondary Containments (i.e., Refueling Floor and Reactor Building ventilation systems) isolated, and partial Group 2 PCIS isolation signals _ vere generated closing selected PCIVs and isolating the Hydrogen and Oxygen Analyzer and Fission Products Monitoring systems.

, . _ , _ . , - , _ . _ , . - _ . _ _ _ - a . - _ _ - . _ . , . , _ . - , .

u.s. mtum ssnuss asmuema An se l' 1H um mA .

toCEET IrU,tBER (2) LER MMBER (S) RAGE (3)

FACILITI * (1) t EAm 1 't.so wun mEv 91 002 00 4 & 5 P1)RT llATCil, ll{IT 1 05000321 _

TEIT The SBGT systems are designed to limit the release of radioactivity to the environment following leakage of radioactivity into the Secondary Containment.

The SBGT systems automatically filter the air from the Secondary Containment following an accident and discharge it via the Main Stack. Each unit's SBGT system consists of tvo identical, redundant, parallel air filtration trains containing the r.ecessary heaters, filter, and exhaust f ans. Normal Secondary Containment ventilation systems isolate to allov the SBGT system to maintain a negative pressure in the Reactor building, including the Refueling Floor, and prevent leakage of the unfiltered building atmosphere to the environment.

The PCIS is designed to limit the release of radioactive materials from the Primary Containment in the event of an act.ident. PCIVs automatically isolate lines penetrating the Primary containment upon receipt of signals (e.g., reactor water lov level, dryvell high pressure) indicating an abnormal condition may exist.

In the events described in this report, the "B" trains of the SBGT systems started, the Secondary containments isolated, and a partial Group 2 PCIS isolation signal was generated resulting in selected open PCIVs closing per design. These a;.tions occurred when a relay coil f ailed and another, nearby relay was bumped during replacement of the failed coil. The first event was equivalent to a loss of power to the affected logic systems. Per IEEE Standard 279-1971, item 4.2, any single failure (including a loss of power) within the protection system shall not prevent proper system operation. Therefore, these logic systems are designed to actuate on loss of pover. This is a " fall-safe" condition.

The second event occurred when the contacts of a relay momentarily changed position due to the force of being bumped. The relay responded as if it had received an actuation signal. The logic downstream of the relay responded correctly to the apparent actuation signal.

All logic systems functioned per design based on the given event. As a result, the "B" SBGT trains vere available should they have been needed in the unlikely event of an accident because they already vere in the actuated condition with the Secondary Containments isolated. Similarly, the affected Group 2 PCIVs vould have isolated Primary Containment should the need have arisen because they already vere in the isolated position with a seal-in isolation signal ptesent.

In addition, proper and immediate actions vere taken when the Hydrogen and Oxygen Analyzer and FPM systems isolated to ansure continued compliance with applicable Technical Specifications requirements.

Based on the above, it is concluded these events had no adverse impact on nuclear safety. This analysis is applicable to all povet levels.

1

"-----'----_m_______.____m... _ . _ _ _ _ _ _ _ _ _ , _

- . - . ~ .

i' A men muun v,s. -- - -

_ _~ _--- cs"s e a wwse 7 -

uwaggy m .

PkC3L1?! Ehles (1) toCEtt mm,Istn (3) 1AR muckst (5) Pact (3)

TEAa sec mai arv ,

PIM HA'!UI, tNTT 1 05000321 91 002 00 5 0F $ l me CORRECTIVE ACTION The coll =of relay 1C61-K24 vas replaced per HVO 1-91-551. The !!ydrogen and Oxygen Analyzer and FPM systems vere returned to service and LCOs 1-91-50 and l 1-91-51 vere terminated. The affected ventilation systems were returned to service, the Group 2 isolation signal was reset, and the "B" SBGT system trains were rentored to the standby condition. i

(

Involved personnel were counseled concerning the need to exercise extreme care whenLvorking in panels containing sensitive equipment. Additionally, this event, its causes, and its consequences vill be. covered with Haintenance personnel during routine toolbox meetings. This action vill be completed by -

3/30/91.

ADDITIONAL-INF0kMATION

-1. Other Affected Plant Systems:

No plant systems other than those listed previously were affseted by this

. event.

2. Previous Similar Events l

.There have been three previously reported similar events in the last two years.in which a failed relay or blevn fuse resulted in an actuation of an ESP. Etese events were reported in LER 50-321/1990-016, dated 9/13/90, LER 50-366/1990-008, dated 10/18/90, and LER 50-366/1991-002, dated 2/18/91.

Corrective actions for these events vould not have prevented this event because different components were involved in each event. Failure of a >

CR120A model relay caused each events however, a. review of the Nuclear Plant Reliability Data System (NPRDS) data base for Plant flatch and other plants indicated a lov failure rate for these relays. Therefore, no additional corrective actions are deemed necessary at this time.

3. Failed Component Information:

Master Parts List Number 1061-K24 Hanufacturer General Electric Type Relay Model Number: CR120A06022AA-Hanufacturer Code: G080 EIIS System Code: Bil 1 EIIS Component Codes RLY Root Cause Codes X Reportable to NTROS: Yes i.

i l

..,._-__-_..-.-...___.,_.__m,.,.- _

- . . - . . . ~ , , o _ _ , _ _ .