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LER 96-007-00 on 961213,engineered Safety Feature Actuations Resulting from Inadequate Planning of step-text Work Order Occurred.Tripped Breaker Reset & LCO Condition Exited
	ML18038B804
Person / Time
Site:	Browns Ferry
Issue date:	01/13/1997
From:	Jay Wallace; TENNESSEE VALLEY AUTHORITY
To:	;
Shared Package
ML18038B803	List: ML18038B802; ML18038B804;
References
	LER-96-007-04, LER-96-7-4, NUDOCS 9701160040
	Download: ML18038B804 (16)
	v • d • e

NRC FORM 366 U. UCLEAR REGULATORY COMMISSION ROVED BY OMB NO. 3150-0104 (4-95) EXPIRES 04/30/96 ESTIMATED BURDEN PER RESPONSE To COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST:

50.0 HRS. REPORTED LESSONS LEARNED ARE L1CENSEE EVENT REPORT (LER) INCORPORATED INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING (See reverse for required number of BURDEN ESTIMATE To THE INFORMATION AND RECORDS digits/characters for each block) MANAGEMENT BRANCH IT.6 F33), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555 FAC(UTY NAME (1) DOCKET NUMBER (2) PAGE (3)

Browns Ferry Nuclear Plant (BFN) Unit 3 05000296 1OFB T)TLE (4)

Engineered:Safety Feature actuations resulting from an inadequate planning of a step-text work order.

EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (6)

FAC(UTY NAME DOCKET NUMBER SEQUENTIAL REVISION MONTH DAY YEAR MONTH DAY YEAR NUMBER ~ ~ NUMBER N/A FACILITYNAME DOCKETNUMBER 12 13 96 96 007 00 01 13 97 N/A OPERATING THIS REPORT. IS SUBMITTED FURS UANT To THE REQUIREMENTS OF 10 CFR I): (Check one or more) (11)

MODE (91 N 20.2201 (b) 20.2203(B)(2)(v) 50.73(a)(2)(l) 50.73(B) (2)(viii) 20.2203(B)(1) 20.2203(B)(3)(l) 50.73(a)(2)(ii) 50.73(B) (2)(x)

POWER LEVEL (10) 100 20.2203(B)(2) (I) 20.2203(B)(3)(ii) 50.73(B)(2) (iii) 73.71 20.2203(B) (2) (ii) 20.2203(B)(4) 50.73(B) (2) (iv) OTHER 20.2203(a)(2)(iii) 50.36(c) (1) 50.73(B) (2) (v) Specify In Abs(rec( below or in NRC Form 366A 20.2203(a)(2) (iv) 50.36(c)(2) 50.73(B)(2) (v)))

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER ()no)ude Ares Code)

James E. Wallace, Licensing Engineer (205) 729-7874 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACrURE R CAUSE SYSTEM COMPONENT MANUFACTURER To NPRDS To NPRDS SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE).

X NO DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On December 13, 1996, with Units 2 and 3 at approximately 100 percent power and Unit 1 shutdown and defueled, Unit 3 experienced unplanned Engineered Safety Feature actuations when an external 120 VAC power supply tripped the Instrument and control panel breaker during the setting of a limit switch setting on a drywell nitrogen supply valve. This condition initiated primary containment isolation valves, specifically, both and torus hydrogen and oxygen analyzers sample and return lines to isolate. The root cause of this event divisions'rywell was an inadequate planning of a step-text work order in that a step was not properly sequenced in accordance with an approved procedure. The tripped breaker was reset and the LCO condition was exited. Corrective actions taken.to preclude recurrence of this type of event were: 1 the Electrical Maintenance planners will be counselled,

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and 2. the Maintenance Managment System procedure will be revised.

This report is being submitted in accordance with 10 CFR 50.73 (a)(2)(iv) as any event or condition that caused ESF actuations.

Previous LERs on similar events were: 50-260/88010, 260/90020, and 260/92008 .

970ii60040 970ii3 PDR ADOCK 05000296 8 PDR

~I NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

I NUMBER NUMBER Browns Ferry Unit 3 05000296 2 of 8 96 "- 007 -- 00 more space is require, use a iuona copies o orm PLANT CONDITIONS At the time of discovery on December 13, 1996, Units 2 and 3 were operating at approximately 100 percent power. Unit 1 was shutdown and defueled.

ZZ. DESCR1PTZON OF EVENT Event On December 13, 1996, at 0136 hours0.00157 days 0.0378 hours 2.248677e-4 weeks 5.1748e-5 months Central Standard Time (CST),

the Unit 3, during the performance of a step-text work order (WO 96-015635-001), the Instrument & Control (I&C) Bus "B" 120 VAC breaker 336 at panel (9-9) [EE] [BKR] to a drywell nitrogen supply valve tripped.

This condition resulted from an external 120 VAC power supply being connected to a circuit that had not been fully isolated during the setting of the limit switches on the drywell nitrogen supply train B Division ZZ solenoid valve [LK] [ISV] (See page 8 of 8). Since the external power supply was attached to a grounded neutral wire, the 120 VAC, 20 amp breaker on panel 9-9 tripped. At that time, both primary containment isolation valves of containment monitoring hydrogen and oxygen analyzers (H202)

[ZK] closed. As a result of isolating the hydrogen analyzers, a Limiting Condition for Operations (LCO) 3.7.H.3 was entered.

At 0137 hours0.00159 days 0.0381 hours 2.265212e-4 weeks 5.21285e-5 months , Operations personnel found that the breaker for the 1&C Panel 9-9 had tripped. At 0139 hours0.00161 days 0.0386 hours 2.29828e-4 weeks 5.28895e-5 months , the breaker was reset, but it tripped again after five seconds. At 0150 hours0.00174 days 0.0417 hours 2.480159e-4 weeks 5.7075e-5 months , the Unit Supervisor (utility, licensed) sent assistant unit operators (AUO) (utility, non-licensed) to investigate the source of the tripped breaker. The AUOs questioned electrical maintenance (EM) personnel (utility, non-licensed) who were setting the limit switches on the drywell nitrogen supply train B Division II solenoid valve. The EMs were requested to stop their work activity and to return the system to the pre-job configuration. At 0159 hours0.00184 days 0.0442 hours 2.628968e-4 weeks 6.04995e-5 months , Operational personnel again closed the breaker. At 0221 hours0.00256 days 0.0614 hours 3.654101e-4 weeks 8.40905e-5 months , the 3A and 3B hydrogen analyzers were returned to service, and the LCO was exited. Plant equipment appeared to have functioned as required.

At 0457 hours0.00529 days 0.127 hours 7.556217e-4 weeks 1.738885e-4 months , a four-hour notification was made to the NRC in accordance with 10 CFR 50.73(b)(2)(ii) . The cause of the event was discovered to be an inadequate planning of a step-text WO being performed by the EMs. At 1300 hours0.015 days 0.361 hours 0.00215 weeks 4.9465e-4 months CST, the step-text WO was revised to isolate the solenoid rectifier from the ZEC 120 VAC circuit, and the work order was performed without an further problems.

NRC FORM 366A (4-95I

II NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-96)

LXCENSEE EVENT 'REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

NUMBER NUMBER

Browns Ferry Unit 3 05000296 3 of 8 96 -- 007 -- 00 more space is require, use a mone copies o orm HISTORY OF TEMPLATE STEP-TEXT WORK ORDER On June 8, 1990, a step-text WO (WO 90-07108-00) was initiated to perform a baseline inspection of the Unit 2 electrical components of the nitrogen isolation solenoid valve (BFN 2-FSV 084-008D) .

During the planning of the work order that provided steps to disassemble the valve, to reassemble the valve, and to set the limit switches on the valve, the planner decided not to incorporate an isolation step as depicted in an approved site procedure (ECI-0-000-SOL002). At that time, the planner placed an isolation step in the disassembly part of the WO instead of the part where the limit switches are set. This initial WO became a template for succeeding WOs. Consequently, on December 11, 1996, when an electrical maintenance planner was requested to develop:a .step-text WO to disassemble, reassemble, and set the limit switches in support of mechanical maintenance on the nitrogen isolation solenoid valve, the planner reviewed past WOs and selected the template WO.

PERFORMANCE OF WO ON DECEMBER 12 AND 13 1996 The December 12, 1996, day shift performed .the electrical disassembly of the valve to prepare for valve maintenance. Since the isolation step was not performed during the disassembly, the isolation step was marked (N/A) not applicable. On the evening shift, valve repair was completed. The setting of the shift. limit switches was left for the December 13, 1996, midnight When the midnight shift performed a pre-job review, the EMs noticed that all preceding steps were signed or marked with an N/A. As a result of the review, they continued on Step 1.9 in the step-text WO. Step 1.9.5 required a 120 VAC external power supply to be connected to the rectifier circuit to the solenoid valve coil to stroke the valve. Since the circuit was not fully isolated, this connection resulted in connecting 120 VAC to the breaker' neutral wire (grounded) . A resultant overcurrent condition caused the breaker to trip.

REPORTING RE UIREMENTS BFN notified the NRC Operations Center of a four-hour non-emergency report in accordance with 10 CFR 50.72(b) (2) (ii) as an event that results in automatic actuation of any ESF.

Additionally, this report is submitted in accordance with 10 CFR 50.73(a)(2)(iv) as an event that results in automatic actuation of any ESF.

B Ino erable Structures Com onents or S stems that Contributed to the Event:

None.

NRC FORM 366A (4-95)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISS)ON l4-95)

LXCENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

I NUMBER NUMBER Browns Ferry Unit 3 05000296 4 of 8 96 -- 007 -- 00 more spece is require, use a ruone copies o orm C. Dates and A roximate Times of Ma'or Occurrencess June 8, 1990 Planner initiated a step-text work order to repair 2-FSV-84-008D. Steps in this work order were not consistent with an approved procedure (ECI-0-000-SOL002).

December 11, 1996 At 2205 hours0.0255 days 0.613 hours 0.00365 weeks 8.390025e-4 months , CST Planner wrote a work order using a 1995 work order template derived from the June 1990 work order.

December 13, 1996 At 0136 hours0.00157 days 0.0378 hours 2.248677e-4 weeks 5.1748e-5 months , CST Breaker on Unit 3 I&C Panel 9-'9 tripped.

Unit 3 entered LCO g 3-96-160-3.7.H.3 due to a loss of both hydrogen analyzers.

At 0150 hours0.00174 days 0.0417 hours 2.480159e-4 weeks 5.7075e-5 months , CST Electrical Maintenance personnel returned system to its pre-job configuration.

At 0221 hours0.00256 days 0.0614 hours 3.654101e-4 weeks 8.40905e-5 months , CST Operations personnel returned the 3A and 3B Hydrogen analyzers to service. LCO was exited.

At 0457 hours0.00529 days 0.127 hours 7.556217e-4 weeks 1.738885e-4 months , CST A four-hour NRC notification was made in accordance with 10 CFR 50.72(b)(2)(ii).

At 1300 hours0.015 days 0.361 hours 0.00215 weeks 4.9465e-4 months , CST The WO was revised, and work on the valve was completed without any additional problems.

D. Other S stems or Seconda Functions Affected:

None.

E~ Method of Discove This event was promptly discovered when control room alarms indicated the opening of the IEC panel (9-9) breaker and the isolation of the Unit 3 drywell and torus H202 analyzers.

0 erator Actions s In this event, steps were taken to identify the isolation problems, and maintenance actions were initiated as appropriate.

G. Safet S stem Res onses:

None.

NRC FORM 366A (4-95)

41 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3) j NUMBER NUMBER Browns Ferry Unit 3 05000296 5 of 8 96 -- 007 -- 00 more space is require, use a ruona copies o orm III ~ CAUSE OF THE EVENT A. Immediate Causes The immediate cause of the events was a trip of the IRC panel 9-9 120 VAC breaker. This condition resulted in de-energizing primary containment isolation valves.

Specifically, the closure of the isolation valves for the drywell and torus H202 analyzers.

B. Root Cause:

The cause of this event was the result of inadequate planning of a step-text WO. Although an approved procedure had proper sequenced steps to isolate the rectifier circuit of the solenoid valve, the planner of a 1990 WO placed a comparable step in the disassembly part of the step-text WO.

This 1990 step-text WO became a template for succeeding, WO for repairing this type of solenoid valve. The planner who wrote the 1996 WO used a WO that was a template of the 1990 WO. Additionally, the planner and the reviewer made no major changes to the 1996 WO.

C. Contributing Factors:

The Maintenance Management System procedure used by the planners did not clearly identify when and how to use step-text instead of established procedures for work instructions.

IV. ANALYSIS OF THE EVENT The H202 analyzers are used to determine the hydrogen and oxygen concentration in the drywell and torus during normal plant operations or following a LOCA. During a design basis accidents, these analyzers are designed to .isolate as part of a group 6 PCIS isolation. Therefore, the consequence of this event during an accident scenario is minimal.

During the 45 minutes that the analyzers were isolated, the loss of power made two containment ventilation valves inoperable.

These inoperable valves resulted in an inability to vent containment under normal operating conditions. However, containment venting was not required for the duration of this event. Additionally, this inability to vent the containment would not have resulted in a containment overpressure condition since applicable emergency operating instruction appendices provide an alternate means to vent the containment.

Therefore, based on the above, this event did not result in a condition outside the design basis of the plant, nor'id it NRC FORM 366A (4-95)

0 NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTZNUATZON FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

NUMBER NUMBER Browns Ferry Unit 3 05000296 6 of 8 96 -- 007 -- 00 more space is require, use a iuona copies o orm adversely affect the health and safety of plant personnel or the public.

V. CORRECTIVE ACTIONS A. Immediate Corrective Actions:

Work order 96-015635-001 was stopped. The system was returned to pre-job configuration. Operations personnel closed the ZEC Panel breaker. Equipment actions appeared to have performed as required. A four-hour notification was made to the NRC in accordance with 10 CFR 50.73(b) (2) (ii) .

Lon -Term Corrective Actions TO Preclude Another Similar Event.

~ The Electrical Maintenance planners will be counselled to be cognizant of the need to consider existing procedural guidance prior to using step-text.

~ The Maintenance Management System procedure will be revised to clearly identify to planners when and how to use step-text instead of established procedures for work instructions.

VI . ADDITIONAL INFORMATION A. Failed Com onents:

None.

B. Previous LERs on Similar Events:

TVA has reviewed previous reportable events have occurred.

BFN LERs to determine if similar Three previous events have occurred:

LER 260 88010 This 1988 LER addressed ineffective preparation and review of a work plan due to personnel error, lack of attention.

The work plan installed a jumper that only bypassed the trip signal but failed to bypass all trip signals in the circuit.

One corrective action was the requirement to review work plans to ensure that sufficient steps were taken to prevent an unplanned ESF actuation. This corrective action would not have precluded this 1996 event in that the planner and reviewer agreed that there was a step in the 1996 WO that would have isolated the circuitry.

NRC FORM 366A (4-95)

I NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I4.95)

L1CENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET LER NUMBER (6) PAGE (3)

I NUMBER NUMBER Browns Ferry Unit 3 05000296 7 of 8 96 -- 007 -- 00 more space is require, use a niona copies o orm LER 259 90020 This 1990 LER addressed an event that de-energized a 480V shutdown board resulting from a procedure inadequacy and personnel error. The event occurred when the power source from a synchronous timer was attached across the shutdown board' breaker control transfer switch. Specifically, the electrical maintenance procedure did not include any direction on the proper DC power source to be used.

Similarities in the 1990 and the 1996 events was that an external power source was used. However, in. the 1990 event, the procedure did not provide an adequate step to ensure that the external power source would not adversely affect existing equipment. Whereas, this 1996 event the WO had a step for isolating plant equipment from the external source.

Therefore, corrective actions taken in the 1990 event would not have precluded this 1996 event.

LER 260 92008 This 1992 LER addressed the issue that an Operations personnel had inadvertently isolated the hydrogen analyzers without a compensatory sample being taken. The similarity in these LERs was that both LERs addressed isolation of hydrogen analyzers. However, the root cause of the 1992 event was an error on the as constructed drawings. Since a drawing error did not contribute to opening the 1&C panel breaker, corrective actions taken in the 1992 event would not preclude this 1996 event.

VII ~ COMMITMENTS The Electrical Maintenance planners will be counselled to be cognizant of the need to consider existing procedural guidance prior to using step-text. This counseling will be completed by February 14, 1997.

The Maintenance Management System procedure will be revised to clearly identify to planners when and how to use step-text instead of established procedures for work instructions. This revision will be completed by April 16, 1997.

Energy Industry Identification System (EIlS) system and component codes are identified in the text with brackets (e.g., [XX]).

NRC FORM 366A (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I4.95I LICENSEE EVENT REPORT (LER)

TEXT CONTZNUATZON

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RACZLZTY NAKE (1) DOCKET LER NUMBER (6) PAGE (3)

I I NUMBER NUMBER Browns Ferry Unit 3 05000296 8 Of 8 96 -- 007 -- 00 more space is require, use a iqona copies o orm SIMPUFIED SCHEMATIC DIAGRAM S+CV4440040 During the PerforTnance of WO $ 4<166%~1

{OTHER CIRCUITRY OMITTED FOR CLARITY)

Pulled fuse-y iocllion Connection 120 VAC Points BREAKER IAC BUS 8 338 Solereid Rectier for N 3-FSV~O OVERCURRENT FLOW PATH 120VAC I.IGHTING 8OARD Elecbical Outlet N

NRC FORM 366A {4-95)

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ML18038B804

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