ML19327C258

LER 89-031-00:on 891012,ac Power Supply Fuse Blew Resulting in Automatic Isolation of Four Outside Air Intakes on Ventilation Sys.Caused by Inappropriate Action.Intake Valves Returned to Svc & Tech Spec 3.3.3.1 exited.W/891113 Ltr

ML19327C258
Person / Time
Site:	McGuire
Issue date:	11/13/1989
From:	Mcconnell T, Sipe A DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-031, LER-89-31, NUDOCS 8911220005
Download: ML19327C258 (8)

Text

--

3 h r J  %* ;n',

' Duke Ibuer Company ' (104) 87.t4000 i McGuireNuclearStation =

, l'O Bas 188 . ,

Cornelius, N C 280.110488 ,

s DUKEPOWER

. , s November 13, 1989 j

, i U.S. Nuclear Regul'atory Commission Document Control Desk [

-Washington, D.C. 20555

Subject:

McGuire Nuclear Station Units 1 and 2 Docket No. 50-369 Licensee Event Report 369/89-31 L

q:

F Gentlemen:  ;

i. Pursuant to 10 CFR 50.73 Sections (a)(1) and (d), attached is Licensee Event Report 369/89-31' concerning both trains:of the Control Area' Ventilation. System being declared inoperable because of an inappropriate . action. This report is '

being submitted in accordance with 10 CFR 50.73(a)(2)(i) and (a)(2)(v). .This event is considered to be of no significance with respect to the health and safety -

of the public.

f Very truly yours, f

/*pf-@ M

-T.L. McConnell DVE/ADJ/cbl-Attachment ,

t xc: Mr. S.D. Ebneter American Nuclear Insurers Administrator, Region II c/o Dottie Sherman, ANI Library J

'.U.S. Nuclear Regulatory Commission The Exchange, Suit 245 ,

101 Marietta St., NW, Suite 2900 270 Farmington Avenue Atlanta, GA 30323 Farmington, CT 06032 INPO Records Center Mr. Darl Hood Suite 1500 U.S. Nuclear Regulatory Commission 1100 circle 75 Parkway Office of Nuclear Reactor Regulation Atlanta, GA 30339 Washington, D.C. 20555 M&M Nuclear Consultants Mr. P.K. Van Doorn l 1221 Avenue of the Americas NRC Resident Inspector ,

New York, NY 10020 McGuire Nuclear Station 9911220005 891113 f>

PDR ADOCK0500g9 S

1\ ,

g ..;g s -. :

' ~LER Cover;Lett r L Ppge 2 '.

• G, '

T ,

i S bxcs'B.W.'Bline y

A.S. Daughtridge J.S. Warren '

i

R.L. Gill:

'R.M.-Glover 1(CNS) '.

T.D. Curtis (ONS) '

'P.R. Herran',

u4 ,

S.S. Kilborn (W)

R.E. Lopez-Ibanez J.J. Maher '

.R.O. Sharpe.(MNS) 3 JG.B. Swindlehurst s K.D. Thomas 1\L L.E. Weaver R.L. Weber J.D. Wylie (PSD)

J.W. Willis

'QA Tech. Services NRC Coordinator (EC 12/55)

MC-815-04 (20) 1 b

b f

\

t p .. ~ . .,s.

r 1 3, ,

'j u . <uCLla .. .uu,o., C., io.,

1,

• D u.a.ss m.

, 3i u .aoveo cue no 3 f t=*me e.See i

'.

• UCENSEE EVENT REPORT (LER) i eaciutv =aast m ooCaet Nuesesa ui rnae cui )

McGuire Nuclear Station, Unit 1 o i s l o j o g o j 3 j6 ; 9 i lor 16 I

"'* Technical Specification 3.0.3 Was Entered On Unit 1 And Unit 2 Due To An Inappropriate i

. Action Durine Maintenance On Theespont Control oatt m Area Ventilation Svatem otMan saciutits iNvolvto e

sveNT oast a ten nummen iei

'ac'ut'***** 00C' t ' Nuwet a'5' I woNr pav vtan vtaa M,4 6 $*g; coNr Dav vtaa )

McGuire Unit 2 01610 i o t o i gg y to l 1

i i i i i e e i 113 81 9 0 is os g o g o,  ; g l 11 0.112 8 9 8I9 01311 010 11 1 v.n. ..Po., .u 1n o ,va.uaN, ro ,NS . ou .tm o, i. C,. i ,C . - , o ii

,,,,,,,,,, n , ..

=aos = i . 3. ,

n .. _

. n .laH i _

X to.73teH3Hvl 73.7t les

. 30 44isHtH6) 00 36teHil

,,., 1 iO i 0 . in H.,

.. m _

. n.,an ,

_ g,=,. g. ,.g.,..

.I86 ai 30 4N4aH1Hdel X to 134sIGilil 50 73IsH3H.seiHAl

.nwi.e, ni.i H..n.,

. .in H ,

M 40$leH1H.) to 73 eH3H iil to 73 aH3Hei Litte,stt C.NT ACT FOR THIS LE A Hal TELEPMONE NVutta NLMt amt& CODE Alan Sine. Chairman. McGuire Safety Review Group 71014 R17 l %I -It. I 11 R l9 CoMPLEf t .Nt LINE FOR SACN C0espoNENT pa Lunt otecnitt0.N TM.S REPORf Hal Sv5Tav "$$he m*0{,fata e

Clust Svlitu COMPONtNT "$$'g aC. R$PO Pa$s' CaV56 COMPONENT I l l I I I t i I I l 1 I I 1 l l l 1 1 I I I I l l l l UON7" Dav Vlam  ;

SUPPLEMENTAL alPont tartCTto itel SvSvtS$l0N

""" i T] vii m ,. . . ameno suevissio= e4 rri ] a.o oi3 ol 1 91 0

.ser a aCT ,L ,~, . , ao . . . . ....,, a,=,. .u. ,,.-e. mv o si On October 12, 1989, Instrumentation and Electrical (IAE) personnel were performing maintenance on the Chlorine Detectors for the Control Area Ventilation (VC) System.

At 1435, IAE personnel were returning the Chlorine Detectors to service by reconnecting power leads. One of the power leads was accidentally dropped and touched the grounding screw. This caused the AC power supply fuse to' blow, resulting in the automatic isolation of the four outside air intakes on the VC system. This resulted in Units 1 and 2 entering Technical Specification

.(TS) 3.0.3. Operations personnel removed power from the outside air intake valves However, Units 1 and then manually opened the valves, thereby exiting TS 3.0.3.

and 2 then entered TS 3.3.3.1 which requires that two channels of the VC Air Intake Radiation Monitorc be operable. The Radiation Monitors could still detect radiation; however, they could not close the VC system outside air intake valves because the power had been removed. IAE personnel replaced the fuse. The intake valves were returned to service, and TS 3.3.3.1 was exited. Unit 1 and Unit 2 were in Mode 1 (Power Operation) at 100 percent power at the time of this event. This event is assigned a cause of Inappropriate Action because the action taken was accidental. Maintenance Engineering Services (MES) personnel will evaluate adding a terminal strip with sliding links and another fuse for the VC Chlorine Detectors.

l c w una o

g ,. , .,'

.' a 400lC Poem 20A U S. NUCLEA3 [lIUL1TORV COMMiettose i P' '-

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION oe:ovio ow. No. mo-em emnes sw.

PACILifyNaMS m , DOCRL1 NUMSSR W LE A NUMSI A 103 PAOS (31 l' " a'i " t'.& 7x,*J:

l'~

McGuire Nuclear Station, Unit 1 o js j o j o l o l 3 l 6l 9 8l9 0l 3[1 Oj0 0l2 0F 0l 6 l text u m . = e w aac f.= assmm EVALUATION: i L Background L

There are two independent trains of the VC [EIIS:VI] System which are designed to maintain a habitable environment in the Control Room [EIIS:NA), Control Room Area, and Switchgear Rooms, during normal and accident conditions. Based on these i criteria, the system is designed as an Engineered Safety Features [EIIS:JE] system I with absolute and carbon filtration [EIIS:FLT] in the outside air intakes and with equipment redundancies for use as conditions require. The Control Room is designed to be maintained at a positive pressure of greater than or equal to 0.125 inches water gauge (w.g.), relative to outside atmosphere during an accident to prevent

• entry of contaminants.

L Chlorine Detectors [EIIS:DET) monitor the outside air intake structure of the VC system for the presence of chlorine gas. Each train has two intake structures.

Each structure is monitored by one detector and has two redundant isolation valves

[EIIS:ISV). If gas is detected by either detector of the train, the train intake structures will be automatically secured by means of closing four intake isolation valves and a local / remote alarm [EIIS: ALM] will be generated. The major parts of a {

chlorine detector are the electrolyte tank [EIIS:TK] that houses a wick, a blower

[EIIS:BLO) unit, and an electronic unit.

TS 3.0.3 states that when a Limiting Condition of Operation is not met, except as

provided in associated Action Statements, within one hour action must be initiated to place the affected units in a mode in which the specification does not apply.

TS 3.3.3.1 states for the VC Outside Air Intake Radiation Monitors [EIIS: MON), EMF 43a and 43b, a minimum of two operable channels [EIIS:CilA] are required. With the number of operable channels less than the minimum requirement, the VC system outside air intakes which contain the inoperable instrumentation must be isolated -

within one' hour.

The Operability Evaluation for PIR 0-M89-0163, Revision 1 dated September 14, 1989 l and expiring February 19, 1990, states:

i In order to achieve acceptable pressure in the Control Room, the doors l [EIIS:DR] in the Control Room were sealed with tape, with the exception of the two doors leading to the Service Building [EIIS:MF], and all four outside air intakes were opened. Based on the test results and the conditions required to achieve the test results, the VC system is Conditionally Operable, with the l conditions of operability being: l l

l - Maintain a tight seal on all the doors in the Control Room. All of the l seams of the Control Room doors (except the two doors leading to the j l Service Building, which are pressure doors) are to be taped. Tape can l subsequently be removed as long as Control Room pressurization l requirements are met.

l l

PMM 306A 'O.8. CP0' 1988*% N'989 000I0

I. 4 -

)

anc

• • "w. anna ue wetimuutarony ca io=

lT UCENSEE EVENT REPORT (LER) TEXT CONTINUATION ueaovio ove w. vio.oio6 exemes. swa j, FAOLITY haut He 00CKlf NUMSSR W ggn hygggM141 P408 (31

) v8Ah  %'$ h*6 -['1*j2

h. McGuire Nuclear Station, Unit 1 o lslojolol3l 6l9 8l 9 -

0l 3l 1 -

0l 00 13 OF 0 l6 rixvwm . w =-w w mswon All four outside air intakes are to stay open except when testing pursuant to TS 4.3.3.1. The operating procedure for the VC system is to be modified to specify all four intakes to be open during normal and y

i accident conditions. The operator will be required to reopen all intakes if they are closed due to the radiation monitar detecting. contaminated

! air in the duct.

The doors which are required to be sealed with tape to maintain an acceptable  !

pressure in the Control Room have been subsequently sealed with a high quality RTV sealant.

! Description of Event- i

, On August 16, 1989, a monthly Preventative Maintenance (PM) was completed on the VC system OMVCMT5010 Chlorine Detector according to work request 03167A. During this PM, which was to check the electrolyte level for the Chlorine Detector, the proper response was received from the appropriate alarms and valves. However, it was discovered that the blower unit and wick needed replacing. Since the monthly surveillance was required to be completed on August 17, 1989, and the alarms and .

valves operated appropriately, work request 69489 was written to replace the blower '

unit and wick. On October 10, 1989, work request 69489 was signed by Operations personnel for IAE personnel to start work on the OMVCMT5010 Chlorine Detector. IAE personnel were using procedure IP/0/B/3012/14, VC System Chlorine Detectors, to '

perform the maintenance. On October 12, 1989, at 1435, IAE Technician A was reconnecting the power leads according to step 10.7.1 in the Return to Service section of the VC System Chlorine Detectors procedure. While IAE Technician A was trying to place the power lead on the terminal strip using a screw starter or holding screwdriver, the screw and power lead fell from the screw starter and landed on the grounding screw in the terminal strip box. This caused a short to ground to occur, which then blew the AC power supply in-line fuse [EIIS:FU). When this, fuse blew, power was lost to all four Chlorine Detectors. This caused all four VC system outside air intakes to isolate. According to the Condition of Operability for the VC system (Operability Evaluation for PIR 0-M89-0163, Revision 1), Units 1 and 2 then entered TS 3.0.3.

IAE Technician A immediately called the Control Room and notified Operations personnel of what had happened. Operations personnel saw that there was a chlorine detection alarm and by looking at the indications for the valve positions they saw ,

that all four VC system outside air intakes had isolated. j 1

At 1510, Operations personnel removed power from the VC system outside air intake valves and manually opened the valves. This enabled Unit 1 and Unit 2 to exit from

'TS 3.0.3. It also placed Units 1 and 2 under another one hour action statement as required by TS 3.3.3.1. With the intake valves manually opened, EMF 43 would not be l able to perform its intended function of closing the intakes if a radiation alarm  ;

occurred. Operations personnel were placed on standby at the breakers for the outside air intake valves, to close the valves in case of a high radiation alarm. )

By 1600, IAE personnel had replaced and functionally tested the in-line fuse, and l Operations personnel had restored power to the VC system Outside Air Intake Valves.

I NIC FOIU 366A *b.$. CNi 108a q ,S w e is.

O .-- ,

.]

+  ;

4 OthC Form NSA U g. esVCLED [ElutAtjaV COMMuBB40se f *** '-- LICENSEE EVENT REPORT (LER) TEXT CONTINUAT13N . uPaovio oue no. mo-om ERPIRES. t?31/N l

(

PACiterv NAest on DOCR41NUMDSR80 Lgp NUMG4R ts) PA04 43) a YIaR NMNm UEu*aIn McGuire Nuclear Station, Unit 1 o p jo lo j o l3 l 6l9 8l9 --

0l 3'l1 --

Ol0 o l4 0F 0 16 vexi m . w. .as w mc r asnav nn L

-Operations personnel had'to manually close the valves and then close the breakers h to return the intake valves to their full open position. This allowed Unit 1 and (J

Unit 2 to exit TS 3.3.3.1. i a -

On November 3, 1989, Operations personnel notified the NRC of a single failure that caused both trains of VC to become inoperable.  ;

Conclusion-E This' event is assigned a cause of Inappropriate Action because the action taken was accidental. While IAE Technician A was placing the power lead on the terminal, the -;

power' lead fell from the' screw starter and touched ground. This in turn blew the '

120V AC power supply to the chlorine detectors in-line fuse, closing all four VC i

! Loutside air-intakes. The procedure requires the power leads to be removed for testing the Chlorine Detectors. Power cannot be isolated by opening a breaker because of other equipment required to be operable. Lifting power leads to test ~)

unisolable low-voltage equipment'is an accepted industry practice. This event <

occurred while the power leads were being replaced to return the OMVCMT5010 Chlorine Detector to service. I AE Technician A was performing this VC system  ;

Chlorine Detectors procedure for the first time as on-the-job training and was not Employee Training and Qualifications System (ETQS) qualified to this task. )

However, the IAE Technician A was performing this procedure under supervisory '

i. direction. This event will be covered with all IAE crews.

A mitigating circumstance is that the terminal box is small which does not allow personnel to hold the power lead in place while terminating it. The use of a holding screwdriver to place a power lead is standard practice for the IAE section.

MES will evaluate adding a terminal box with sliding links in line with existing wiring and take apprepriate actions as necessary.

The AC power supply to the chlo.-ine detectors in-line fuse was added recently during the Unit 2 End of Cycle 5 Outage according to Nuclear Station Modification (NSM) MG-1-0071. This NSM modified the 125 VDC Auxiliary Control Power System by 1 adding miscellaneous fuses to make the non-essential controls powered from the KXA l Inverter [EIIS:INVT] to power panelboard [EIIS:BD) KXA more reliable. A 5 Amp fuse j was added to protect the Radiation Monitor and Chlorine Monitor circuits for the  ;

VC System. If this event had occurred prior to this NSM being implemented several i

, other systems in addition to the VC system would have become inoperable (e.g. I Reactor Building Purge System [EIIS:VA]). MES personnel will evaluate adding another fuse for the Chlorine Detectors circuitry to ensure train separation and redundancy and will take appropriate action as necessary. This event is still being investigated and an addendum will be written with the results of the investigation. l Operations personnel prepared for the possibility of the replacement of this in-line fuse taking over an hour, by securing the four intakes in an open position.

With the intakes secured open, if a high radiation alarm on EMF 43 had occurred, L the outside intake valves could not automatically close. Therefore, TS 3.3.3.1 was L entered because EMF 43 was rendered inoperable. Operations personnel were on

. a . cro, m . - - .  !

%' J

v ->

4.

J[* . .

,,, vs. =Uct AmuuuroRv communios.

H}' ,

i.lCENSEE EVENT REPORT (LER) TEXT CONTINUATION uenovio ove ao mo-N ,

IXPIRES $/31/N PAC 8LffV hAhet it) DOCERT NUMB 4R 12) LtR NUMSOR 16) PAGE (3)

" O!.M '. s 7#.#

b McGuire Nuclear Station, Unit 1 olslojojol3lq9 8l 9 0l 0 0l5 0l 3l 1 -- OF 0 l6 TEXT (# mee ausse e mFureef. was 88uimoner MIC Fem M W 07) standby at the outside air intake valve breakers to be ready to close the breakers if a radiation alarm was received.

Both one hour TS Action Statements, TS 3.0.3 and 3.3.3.1, were met.

L A review of the past 12 months using the Operating Experience Program data' base for

. McGuire revealed 9 TS violation events or entry into TS 3.0.3 events with a general cause of Inappropriate Action. -However, there were no TS related events with a cause of accidental Inappropriate Action. Therefore, this event is not considered t recurring.

There have been'two events at McGuire in the past 18 months that documented' .

Inappropriate Actions that caused Engineering Safety Features Actuations (ESFA).

Licensee Event Report (LER) 360/88-8 involved Performance personnel performing a valve [EIIS:V] stroke timing test where a power lead inadvertently made contact

.with the electrical circuitry of the Turbine Driven Auxiliary Feedwater Pump. This

' caused.a fuse to blow and an ESFA to occur. LER 369/89-25 involved Performance personnel performing a valve stroke timing test where a jumper placed across a sliding link came loose and inadvertently made contact with another sliding link, thereby, causing a fuse to blow and an ESFA'to occur. Based on the above events the problem of Inappropriate Actions because of dropping power leads or jumpers is considered recurring.

' This event is not Nuclear Plant Reliability Data System (NPRDS) reportable.

There were .no personnel injuries, radiation overexposures, or uncontrolled releases .

of radioactive material as a result of this event. "

- CORRECTIVE ACTIONS:

1 Immediate: 1) Operations personnel removed power to the VC system Outside Air Intake valves and manually opened the valves, thereby, exiting TS 3.0.3 and entering TS 3.3.3.1.

2) Operations personnel were placed on standby at the Outside Air Intake valve breakers to close the valves in case of a high  ;

radiation alarm. <

Subsequent: 1) IAE personnel replaced and functionally checked the in-line fuse on the Chlorine Detectors.

2) Operations personnel returned the VC System Outside Air Intakes to service by restoring power to them and returning them to the full open position thereby exiting TS 3.3.3.1.

Planned: 1) This event will be covered with all IAE crews.

I 2) MES personnel will evaluate aduing a terminal box with sliding L links in line with existing wiring and take appropriate action as necessary.

une row un ***m'""*^"*'

W. .

b'.- Olhc Perut 3084 U $ NUCLEI @ [61ULifoRY COMMtESION i,

LICENSEE EVENT MEPORT (LER) TEXT CONTINUATION ' ue ovio ows No 3+om  ;

ExPints t/3 pas i P40luTV haast ni DOCKET NUMBER W LgR NUMSER $ PA06 43) vgAn 8 Q [ , <

"g*y McGuire Nuclear Station, Unit 1 o ls go jo jo l 3l q 9 8l 9 ._

q 3l 1 __

Og 0 0l6 0F 0l&

nmT u . m w ww u am4w nn  ;

1

3) MES personnel will evaluate adding another fuse for the ,

Chlorine Detectors to have a fuse for each train and will take appropriate action as necessary.

4) An addendum will be written on the results of the investigation of the blown fuse causing both trains of VC to become' inoperable.

SAFETY ANALYSIS:

The design requirements of the VC syst.em are to supply filtered air at a controlled temperature and humidity to the Control Room and to pressurize the Control Room to  !

prevent inleakage of unfiltered air. The VC system helps ensure that doses to Control Room personnel are As Low As Reasonably Achievable and remain below Code of Federal Regulations, Title 10, Part 50 (10CFR50), Appendix A, Criteria 19 (GDC-19) limits.

1 The TS 4.7.6 requirement specifies that a Control Room positive pressure of greater than.or equal to 0.125 inches v.g. relative to outside atmosphere during system operation must be demonstrated at least once every 18 months. A positive pressure y of 0.05-inches w.g. is-considered sufficient to prevent inleakage in excess of 10 cubic feet / minute, which is the assumed leakage value used for radiation dose ,

calculations in Chapter 15 of the Final Safety Analysis Report (FSAR).

The Operability Evaluation for PIR 0-M89-0163 results showed that both outside air pressurization filter trains were able to pressurize the Control Room greater than the 0.1C5 inches w.g. with all four outside air intakes open. With two intakes open, the Control Room pressure was still positive but less than the required 0.125 inches w.g.

P The principle contaminent contained in air leaking into the Control Room is' assumed to.be Iodine which is very conservatively modeled in dose calculations. Very low amounts of Iodine would be expected to reach the area around the Control Room since this requires passage through either Auxiliary or Turbine Building Ventilation ~

systems or passageways.

Control Room Operator dose would be further reduced by operation of the Auxiliary Building Ventilation system which is not safety related but has been maintained to safety standards. l i- In the event that Control Room atmosphere became unbreathable, self contained I breathing apparatus respirators provided in the Control Room area could be l E employed. Radiation monitors in the Control Room would alert Control Room l personnel of high radiation levels. I

~During this event, Operations personnel had manually opened the VC system outside air. intake valves; therefore, the Control Room pressurization would have been l i maintained had it been necessary. i The health and safety of the public were not affected by this event. l l

l

. _ __ _ _ N "' "I"" ,