ML20011F742

LER 90-002-00:on 900127,control Room Isolation Occurred When Circuit Breaker Opened Supplying Power to Radiation Monitor. Caused by Failure by Personnel to Exercise Sufficient Caution.Responsible Engineers reinstructed.W/900226 Ltr

ML20011F742
Person / Time
Site:	Sequoyah
Issue date:	02/26/1990
From:	Bynum J, Hipp G TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-002-02, LER-90-2-2, NUDOCS 9003070354
Download: ML20011F742 (5)

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[*U , [*. 4 TENNESSEE VALLEY AUTHORITY-  ;

6N'38A Lookout. Place

, t. Chattanooga, Tennessee- l

• February 26,;1990: R

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f U.S. Nuclear Regulatory Commission ATTNi Document' Control Desk 1 l

Washington,-D.C. :20555 1& . . .

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y. ' Gentlemen:

[  : TENNESSEE VALLEY AUTHORITY - SEQUOYAH NUCLEAR PLANT UNIT 1 - DOCKET NO. '

l .50-327.- FACILITY OPERATING LICENSE DPR LICENSEE EVENT REPORT (LER) 50-327/90002' ,

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1

'The enclos'ed-LER provides details of an event wherein a control room isolation '

7 occurred, and-LCO 3.0.3 was entered as a result of both main control room air ,

intake-radiation' monitors being inoperable. This event is being reported'in l-accordance with 10 CFR 50.73, paragraphs a.2.i and a.2.iv.

I I

Very tEuly yours, '

[ TENNESSEE VALLEY' AUTHORITY q

- l j, . R. Bynum,., ice < President.

L Nuclear Power Production.

Enclosure cc (Enclosure):

Regional Administration U.S.. Nuclear Regulatory Commission 1

-Offico of Inspection and Enforcement l Region II _

101 Marietta Street, Suite 2900 .j Atlanta, Georgia' 30323 >

1

'INPO Records Center Institute of Nuclear Power Operations 1100l Circle 75 Parkway, Suite 1500 1 Atlanta.-Georgia 30339 -l

'Q NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road 1

-Soddy Daisy,. Tennessee 37379 t

9003070354 900226 #

PDR ADOCK 05000327 b),

A PTIC #

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An Equal Opportunity Employer

C ORM 304 U S. NUCL E AR f.E TULAT 0lY COMMISSION APPR0vtD OMS No.31600104 IKPtHES:4/30/C2 ESTIMATED BURDEN ftR RESPONSE TO COM7LY WTH THl$

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C F ACILITY NAME l11 DOCILE T NUMBER (2) . PAGE G Saquoyah Nuclear Plant, Unit 1 0l5]O10l0l3l2l7 1 lOFl 014 "f* Main control room (MCR) isolation and LCO 3.0.3 entry because both MCR air intake r diation monitors were inoperable as a result of accidental bumping of circuit breaker.

EVENT DAf t 166 LER NUMetR 161 REPORT DATE 17) OTHER F ACILITIES INVOLVED 106

FACokiTv hAMts MONTH DAY YEAR YEAR -

88,0 9V n QU'"[ MONTH DAY YEAR DOCKET NUMBERI5I Sequoyah, Unit 2 0 15101010 131218  :

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LICENSEE CONTACT POR TMit Ltm H2)

NAME TELEPHONE NUM8ER ARE A CQQE C=of Hipp. Compliance Licensinn Ennineer 6Ill5 81 41 31 -l 71 71616 COMPLETE ONE LINE FOR E ACM COMPONENT F AILURE DESCRISED eN TMis REPORT tt36 REP 0HTA Lt M 8AC- REPORTA E ,

CAU$4 SYST EM COMPONENT M$NC p A $E SY STE M COMPONINT g I I I l l l l l I I i 1 l l l 1 1 I I I I I I I I I I I

$UPPLEMENTAL REPORT EXPECTED (14) MONTH DAY VIAR SU9 Mis $ ION 4 tS III r.t comp ore IK9tCTED sv0Mr3St0N Da VEI f ko no,. a rre-m. s .a oei l l l Aoan ACT a-r M ia - . . .n,..~. ley r.rM.n At 1325 on January 27, 1990, with both Unit 1 and Unit 2 at 100 percent power, an inadvertent control room isolation (CRI) occurred when a circuit breaker opened that was supplying power to a radiation monitor (RM) on the control room emergency ventilation system (CREVS). The opposite train of CREVS was also inoperable at the time because of s surveillance testing; therefore, the plant entered Limiting Condition for Operation  !

(LCO) 3.0.3. Personnel had been pull-testing anchor bolts attached to the-ceiling above the electrical panel containing the circuit breaker. The breaker handle was bumped while passing equipment up and down a 10-foot step ladder. The shift operations supervisor (SOS) reset the circuit breaker at 1330 EST, returning the RM to service, and LCO 3.0.3 was exited. The root cause of this event has been attributed to a failure by psrsonnel to exercise sufficient caution and attention to detail. As corrective action, the engineers with responsibility for workplan preparation have been instructed to g Esvaluate the work involved in current and future workplans to determine if a specific statement needs to be added directing prework inspection of the jobsite by the SOS or assistant SOS for potential hazards.

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. Description of Event At 1325 Eastern standard time (EST) on January 27, 1990, with both Unit i and Unit 2 in

' Mode 1 (100 percent power, 2,235 pounds per square inch gausge, 578 degrees Fahrenheit),  !

cn inadvertent control room isolation (CRI) occurred when a circuit breaker opened that l w:s supplying power to Radiation Monitor (EIIS Code IL) 0-RM-90-126 on the main control room air intake. This radiation monitor supplies an input signal to the Train B of control room emergency ventilation system (CREVS) (EIIS Code VI). Removing power to the radiation monitor created an input signal to initiate the Train B CRI. Coincidentally, Train A of CREVS was inoperable at the time because surveillance testing was being conducted on Train A main control room air intake Radiation Monitor 0-RM-90-125.

Therefore, both main control room air intake radiation monitors were inoperable and, i consequently, both trains of CREVS were inoperable. Because Limiting Condition for i Operation (LCO) 3.7.7 requires two independent CREVS to be operable and also has a l Mode 1 action statement addressing only one inoperable CREVS, LCO 3.0.3 was entered as I of 1325 EST. l l

The subject circuit breaker is located in 125-volt Battery Board Room II (EIIS Code EJ) in the auxiliary building (EIIS Code NF). When the breaker opened, two electricians and l a quality control inspector were in the battery board room performing pull-testing of l anchor bolts for conduit supports attached to the room ceiling. The work consisted of using a portable hand pump and hydraulic ram to pull-test embedded anchors. A'10-foot step ladder was being used to reach the anchors and was located approximately 18 inches past the end of the electrical panel containing the circuit breaker. It is surmised l that, while handing the portable pump and hydraulic ram up and down the ladder, the l connecting hose came 4.n contact with the circuit breaker handle causing the breaker to l: open. The personnel in the battery board room did not know the breaker opened and were L unaware a CRI had occurred. After immediately investigating the CRI and determining it

l. to be spurious, the shift operations supervisor (SOS) reset the circuit breaker at l 1330 EST, returning Radiation Monitor 0-RM-90-126 to service, and LCO 3.0.3 was exited.

t Csuse of Event The root cause of this event has been attributed to a failure by the personnel working in the battery board room to exercise sufficient caution and attention to detail in view of the restricted working space available. The clearance between the ladder and the electrical panel would normally have been sufficient to prevent accidental contact with the circuit breaker. In view of the equipment being handed up and down the ladder, the clearance allowed was not sufficient. However, because of obstructions overhead, the ledder had been positioned as far as practical from the panel.

A contributing cause of the event was the design of the electrical panel relative to the working environment in the battery board room. The face of the panel is flat with only the circuit breaker handle exposed. The breakers, 15-ampere Heineman CF style, do not require much force for the handle to open.

NRC 7 tem 348 A (649)

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f ACILITV NAMS (1) DOCKET NUMetR (2 LtR NUMetR let PAGF (3) .j M'" NNIm va p 62quoyah Nuclear Plant, Unit 1 o l5 l0 l0 lo 13l 2l 7 9l0 -

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0 l0 0l3 OF 0 l4 TEXT f2 more apoco 4 toeused, use a#const 4,TC Form J864 'st (17)

Analysis of Event L This_ event is being reported in accordance with 10 CFR 50.73, paragraph a.2.1, as an i operation prohibited by technical specifications because LCO 3.0.3 was entered, and also

~in accordance with 10 CFR 50.73, paragraph a.2.iv, as an unplanned actuation of an angineered safety feature (ESP) because a CRI occurred.

The main control room habitability system, is described in Section 6.4 of the SQN Updated Final Safety Analysis Report (UFSAR). The control building air-cleanup system and the heating, ventilation, and air-conditioning system are described in Section 9.4.1 of the UFSAR. Additionally, the main control room air intake radiation monitors are dsscribed in Section 11.4.2.2.'5 of the UFSAR. The CREVS is designed to provide a safe environment for personnel controlling plant operations during normal operations and during accidents. There are two 100-percent redundant equipment trains for CREVS--Train A and Train B. Train A was inoperable at the time of this event for surveillance testing on Radiation Monitor 0-RM-90-125. When the circuit breaker

-supplying power to Radiation Monitor 0-RM-90-126 opened, both trains of CREVS were i inoperable._ However, the function of these two radiation monitors is to detect high l

radiation levels in the main control room air intake and, upon detecting high radiation j isvels, to initiate a CRI to protect the main control room environment from l

contamination. Because a CRI was initiated when the circuit breaker opened, it can_be j l.

concluded that the radiation monitors had fulfilled their design function to protect the l main control room environment. Therefore, there was no adverse effect on the health and i esfety of the public or plant personnel. i Corrective Action The immediate actions taken were to determine the cause of the CRI and, upon resetting ,

the circuit breaker that had opened, to restore the radiation monitor to service and to '

restore one train of CREVS to operability. As corrective action to prevent recurrence, the engineers with responsibility for workplan preparation have been instructed to evaluate the work involved in current and future workplans to determine if a specific statement needs to be added directing additional caution. Such a statement would direct  ;

the craft foreman to contact the SOS or assistant shift operations supervisor (ASOS) to i look at the jobsite and point out any potential problem areas. These potential problem

. areas would be noted in the work authorizing document. A night order to the SOSs/ASOSs has been written directing their review of the jobsite to point out potential problem areas prior to work authorization.

NRC Pym 386A (649)

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PAClelii NAME Of DOCitET NUMBER (2) LER NUMSER (6) PAGE (3) v5AR se a At mi syn N n q e Ssquoyah Nuclear Plant, Unit 1 o l5 l0 l0 l0 l 3l 2l 7 9]O -

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0 l0 0l4 '0F 0 l4 YExT w one ma m. em m uc rn may nn Additional Information There have been 19 previously reported occurrences of CRIs at SQN since 1984. Of these 19 occurrences, two involved accidental bumping of CRI-related components. Several other ESF actuations since 1984, such as an auxiliary building isolation, have also been attributed to accidental bumping of equipment. Previous corrective actions such as training, counselling, improvements to prejob planning, and minimizing work around snergized equipment have been implemented. No common thread, such as personnel involved, equipment / location involved, or work / operation involved, has been identified.

These events do not happen frequently (less than two per year), and it is believed they are unrelated. .

NRC Penn 364A (IkS9)