ML18038B986

LER 97-005-00:on 971012,ESF Components Were Actuated.Caused by Inadequate Procedure.Cs Pumps Were Secured & Injection Valves Were Closed & Refueling Floor Activities Were Stopped

ML18038B986
Person / Time
Site:	Browns Ferry
Issue date:	11/10/1997
From:	Jay Wallace TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18038B985	List: ML18038B984 ML18038B986
References
LER-97-005-03, LER-97-5-3, NUDOCS 9711180019
Download: ML18038B986 (14)

Text

NRC FORM'366 U.s. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31504104 t

(4-95) EXPIRES 04/30/96 ESTIMATED BURDEN PER RESPONSE TO COMPI.Y WITH THIS MANDATORY INFORMATION COLLECTION REQUEST:

Ll:CENSEE EVENT REPORT (LER) 50.0 HRS. REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE UCENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING

{See reverse for required number of BURDEN ESTIMATE TO THE INFORMATIONAND RECORDS digits/characters for each block) MANAGEMENT BRANCH {TA F33), U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 2055&0001.

FACILITY gAME II) DOCKET NUMBER (TI PAQE ts)

Browns Ferry Nuclear Plant (BFN) Unit 2 05000260 1 OF 7 TITLE Iai ESF components were actuated as a result of an inadequate procedure. This is reportable due to ESF actuations in accordance with 10 CFR 50.73(a)(2)(iv).

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

FACILITYNAME DOCKET NUMBER MONTH DAY YEAR SEQUENTIAL'EVISION MONTH DAY YEAR NUMBER NUMBER BFN Unit 1 05000259 FACIUTY NAME DOCKET NUMBER 10 12 97 97 005 00 10 97 BFN Unit.3 05000296 OPERATING THIS REPORT IS SUBMITTED PURS UANT TO THE REQUIREMENTS OF 10 CFR: {Check one ormore) (11)

MODE {9) N 20.2201(b) 20.2203(a)(2)(v) 50.73(a) (2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) '0.2203(a)(3)(i) 50.73(a) (2)(ii) 50.73(a)(2)(x)

LEVEL (10) 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) OTHER 20.2203{a) 50.36(c) (1) 50.73(a)(2)(v) Speci/Y In Abstract below or in NRC Form 366A

{2)(iii)'0.2203(a)(2)(iv) 50.36(c) (2), 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

TELEPHONE NUMBER Iinorude Area Coda)

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

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). DATE (15)

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

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On October 12, 1997, at approximately 0559 hours0.00647 days <br />0.155 hours <br />9.242725e-4 weeks <br />2.126995e-4 months <br />, Unit 2 was in cold shutdown in a refueling outage. Unit 3 was at 100 percent power. Unit 1 was defueled. At that time, a Unit 2 post modification test was being performed for a modification on the Unit 2 main steam relief valves. Instrumentation and Controls (I&C) personnel inadvertently made contact with two relay terminals simultaneously while attaching an alligator clip to one of the relay terminals. This initiated several engineered safety feature actuations. The root cause was a result of an inadequate procedure.

Immediate corrective actions included: (1) CS pumps were secured and injection valves were closed, (2) refueling floor activities were stopped, (3) EDGs were secured and placed in standby, (4) alligator clips were removed', and the PMT was halted, and (5) PMT was revised and was successfully performed. Corrective actions to preclude recurrence include: (1) The Modification Test Program procedure wiil be revised, and (2) l8C personnel will review the problem evaluation report associated with this LER to sensitize personnel to the proper use of test clips. As a result of the ESF actuations, this report is submitted in accordance with 10 CFR 50.73 (a)(2)(iv) as a condition that resulted in the manual or, automatic initiation of any ESF. There were several previous LERs (260/87006, 260/88018, 259/88019, 260/89005, 260/89020, 259/90008, 259/94001, 260/94012 and 259/95001) for jumper problems.

97iii800iq 05000260 97iii0 PDR ADQCK S PDR NRC FORM 366 (4-95)

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACZLZTY NAME ( DOCKET LER NUMBER PAGE NUMBER NUMBER Browns Ferry, Unit 2 05000260 2 of 7 97 -- 005 -- 00 TEXT ( more space is required. use addiuona copies o orm (17)

PLANT CONDZTZONS At the time of the discovery of the condition, Unit 2 was in cold shutdown in a refueling outage with the reactor cavity flooded and the fuel pool gate removed., Unit 1 was shutdown and defueled. Unit 3 was at approximately 100 percent power.

ZZ. DESCRZPTZON OF EVENT Event On October 12, 1997, at 0559 hours0.00647 days <br />0.155 hours <br />9.242725e-4 weeks <br />2.126995e-4 months <br />, Central Daylight Time (CDT),

Unit 2 Control Room personnel received an invalid Engineered Safety Feature (ESF) signal on low reactor water level during the refueling outage. While performing a Post Modification Test (PMT) for the functional testing of the Unit 2 logic of the main steam relief [SB] valves, Instrumentation and Controls (1&C) personnel (Utility, Non-licensed) shorted two terminals on a relay [RIY].

The electrical short was between two exposed lugs (M4 and B4) on an Agastat relay 2-63-003-0204AA (See Figures 1 and 2). The M4 lug is associated with a 120 VAC circuit, while the B4 lug is associated with a 24 VDC circuit. When the two lug's were shorted, an arc was observed, and several relays were heard actuating. This short resulted in the invalid low reactor water level signal.

Core Spray (CS) Loop I [BM] initiated and injected into the vessel.

All eight (8) Unit 1, 2,and 3 emergency diesel generators (EDGs)

[EK], and their associated Residual Heat Removal Service Water pumps

[BI] 'started. At this time, CS/RHR Division II was out-of service.

Additionally, a full scram was received due to a low scram pilot air header pressure initiated by an anticipated transient without scram (ATWS) and Alternate Rod Insertion (ARI) signal. The CS loop I was promptly secured. Although the Residual Heat Removal (RHR) system [BO] received an initiation signal, the pumps did not start due to suction valves being closed as a result of the shutdown cooling alignment. Since the condensate supply and storage system

[KA] was supplying charging water to the RHR/CS systems, subsequently injected additio;.al water into the reactor vessel.

it The CS valves were closed. The. water injections into the reactor vessel diminished the clarity of the water.

At 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> refueling floor work was suspended due to diminished reactor cavity water clarity. Reactor cavity water clarity began to improve. The EDGs continued to run unloaded in accordance with plant procedures.

At 0642 hours0.00743 days <br />0.178 hours <br />0.00106 weeks <br />2.44281e-4 months <br />, the reactor scram, ESF, and ARI signals were reset.

At 0655 hours0.00758 days <br />0.182 hours <br />0.00108 weeks <br />2.492275e-4 months <br />, the Unit 1 and 2 EDGs were stopped. At 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br /> RHR Division I was realigned to standby/shutdown cooling.

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATEON PACILITX NAME (l) DOCKET LER NUBBER ( ) PAGE NUMBER NUMBER Browns Ferry Unit 2 05000260 3 of 7 97 -- 005 -- 00 TEXT ( more space is required. use addiuona copies o N orm ) (17)

At 0702 hours0.00813 days <br />0.195 hours <br />0.00116 weeks <br />2.67111e-4 months <br />, Unit 3 EDGs were stopped As a result of the ini:tiation of the ESFs, this report is submitted in accordance with 10 CFR 50.73 (a)(2)(iv) as a condition that resulted in the manual or automatic initiation of any ESF; B. Inc arable Structures Co onents or S stems that Contributed to the Event:

None.

C. Dates and A roximate Times of Ma'or Occurrences:

October 12, )997 At 0144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />, CDT PMT was started for MSRV Pressure switch modification.

At 0559 hours0.00647 days <br />0.155 hours <br />9.242725e-4 weeks <br />2.126995e-4 months <br />, CDT An arc was observed while attaching, an alligator clip to the lug of a terminal on an Agastat relay.

Control Room received a full scram signal. CS pumps initiated and were secured. EDGs actuated. CS isolation valves were closed.

At 0600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />, CDT Refueling floor activities were suspended due to reactor cavity water clarity being diminished.

At 0605 hours0.007 days <br />0.168 hours <br />0.001 weeks <br />2.302025e-4 months <br />, CDT A four-hour notification was made.

RHR injection valves were closed.

At 0642 hours0.00743 days <br />0.178 hours <br />0.00106 weeks <br />2.44281e-4 months <br />, CDT The reactor scram, ESF, and ARE signals were reset.

At 0655 hours0.00758 days <br />0.182 hours <br />0.00108 weeks <br />2.492275e-4 months <br />, CDT Unit 1 and 2 EDGs were stopped.

At 0700 hours0.0081 days <br />0.194 hours <br />0.00116 weeks <br />2.6635e-4 months <br />, CDT RHR Division I was realigned to standby/shutdown cooling.

At 0702 hour0.00813 days <br />0.195 hours <br />0.00116 weeks <br />2.67111e-4 months <br />sr CDT Unit 3 EDGS were stopped.

D. Other S stems or Seconda Functions Affected:

None E. Method of Discove During the performance of a PMT, a full scram signal and ESF actuations were received in the control room.

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NRC FORM 366A U.S. NUCLEAR REGUL'ATORY COMMISSION (4-95)

LICENSEE: EVENT REPORT (LER)

TEXT CONTINUATION FAG ILITr NAME ( I DOCKET LER NUMBER ( ) PAGE NUM8ER NUM8ER Browns Ferry Unit 2 05000260 4 of 7 97 -- 005 -- 00 TEXT ( more space is required. use addiuonal copies o orm 3 (17) erator Actions:

Operations personnel performed the following immediate corrective actions: (1) CS pumps were secured and injection valves were closed, (2) refueling floor activities were stopped, and (3) EDGs were secured and placed in standby.

G. Safet S stem Res onses:

Unit 2 RHR received an initiation signal but did not inject into the reactor vessel. Unit 2 CS pumps injected into the reactor vessel. All eight (8) EDGs auto-started.

ZZZ. CAUSE OF THE EVENT A. Immediate Cause:

The immediate cause of the condition was that two circuits (120 VAC and 24 VDC) were inadvertently shorted together when an alligator clip made contact with two exposed lugs on a relay terminal block.

B. Root Cause:

The root cause of this event was an inadequate procedure.

Specifically, Site Standard Procedure (SSP)-8.3, "Modification Test Program", did not require a performing and support organization review in the PMT approval p ocess.

C. CONTRIBUTING FACTOR The front to back distance between the two exposed lugs (M4 and B4) (See Figures) was narrowed due to the lugs being bent toward each other. Consequently, the use of alligator clips might not have been appropriate.

ZV. ANALYSIS OF THE EVENT The EDGs are part of the standby AC power system which provides a highly reliable source of powe" as required for the Emergency Core Cooling Systems. The EDGs ensure that no credible event can disable the power systems/components.

In this event the EDGs and associated components performed as designed. CS injected into the reactor cavity. Operations personnel immediately identified the cause of the ESF actuations and the reactor scram and took appropriate actions to restore the affected systems to the pre-event configuration. Therefore, this event did not adversely affect the health and safety of the plant personnel or the public.

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME I) DOCKET PAGE NUMBER NUMBER Browns Ferry Unit 2 05000260 5 of 7 97 005 -- 00 TEXT ( more space is required, use addiuoiial copies o orm ) I17)

The PMT of this modification would not have been performed while the plant was operating because multiple safety relief valves would energized simultaneously, which would have been placed .the plant in an unsafe condition. For this type of PMT, the plant would have to be in a condition that ensures minimum impact on the modified unit.

CORRECTIVE ACTIONS A. Immediate Corrective Actions:

Operations personnel performed the following immediate corrective cations: (1) CS pumps were secured and injection valves were closed, (2) refueling floor activities were stopped, and (3) EDGs were secured and placed in standby. I&C personnel removed all alligator clips and halted" the PMT. PMT was revised and was successfully performed.

B. Corrective Actions to Prevent Recurrence:

SSP-8.3 will be revised to include support organization(s) involvement in PMT preparation walkdown and review/approval stages.'&C personnel will review the problem evaluation report to heighten their sensitivity to the proper use of test clips.'I.

ADDITIONAL INFORMATION Failed Co onents:

None.

Previous LERs on Similar Events There were several previous LERs that resulted from misplaced jumpers: 260/87006, 260/88018, 259/88019', 260/89005, 260/89020, 259/90008, 259/94001, 260/94012, and 259/95001.

LER 260/87006 resulted from a jumper that became dislodged due to a congested cabinet. LER 260/88018 resulted when a spring-loaded hook jumper was inadvertently grounded while placing the jumper on a terminal bio'ck. LER 259/88019 occurred when a jumper fell off a terminal screw head.

This action is being tracked by TVA's corrective action program and is not considered a regulatory commitment.

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILZTX NAZE 1) DOCKET PAGE NUMBER NUMBER Browns Ferry Unit 2 05000260 6of 7 97 --, 005 "- 00 TEXT more space is require, use a diliona copies o orm ITT)

LER 260/89005 was caused when a jumper was placed on the wrong terminal. LER 260/89020 occurred when a jumper was placed on the wrong terminal due to an unfamiliarity with the circuitry. LER 259/90008 was a result of a misplaced jumper because the terminal was not labeled. LER 259/94001 happened because an ineffective second-party verification. LER 260/94012 occurred as a result of a misread procedure in that a step in the procedure read installation of a contact boot and a jumper was installed instead. Finally, LER 259/95001 resulted from a drawing deficiency in that the drawing did not accurately reflect in-field wiring.

In this LER (260/97005), the relay was. not in conflict with plant drawings, no second-party verification was required; the relay was properly labeled; personnel were familiar with the PMT circuitry; the procedure was not misread, the jumper did not become dislodged. Therefore, LER 260/88018 was the most similar LER to this LER. The corrective actions in LER 260/88018 was to verify the need to optimize the location (installation of banana clips) in the circuit for jumpers. The need for banana clips were to be. based on probable consequences, frequency of performance, and past problems. The PMT involved in this LER was a one-time test and did not meet the last two corrective action criteria. Therefore,, banana clips were not installed for the PM'II.

.COMMITMENTS

• None. ~

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

4~ i II NRC FORM3CCA U.S. NUCLEAR REGULATORY COIVMSSION (4-96)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME I) DOCKET LER NUMBER PAGE )

NUM8ER NUMSER Browns Ferry vn't 2 05000250 7 of 7 97 -- 005 -- 00 TEX mora space is require, use sddiuons copes orm FIGURES 1 and 2 C

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