ML18096A632

LER 92-004-00:on 920315,2B4D 4 Kv Breaker Tripped Open on Phase C Time Overcurrent When Containment Fan Coil Unit 24 Started.Caused by Personnel Error.Individuals Disciplined & Applicable Procedures revised.W/920413 Ltr

ML18096A632
Person / Time
Site:	Salem
Issue date:	04/13/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-004-02, LER-92-4-2, NUDOCS 9204200203
Download: ML18096A632 (6)

Text

• Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station April 13, 1992 U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT*NO. 2 LICENSEE.EVENT REPORT 92-004-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73(a} (2) (iv). This report is* required to be issued within thirty (30) days of event discovery.

]ely yours, C. A. Vondra General Manager ~

Salem Operations MJP:pc Distribution 9204200203 920413 PDR ADOCK 05000311 S PDR

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-89) APPROVED OMB NO. 3150-0104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSl;E EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-530). U.S. NUCLEAR

., REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). O.FFICE I

OF MANAGEMENT AND BUDGET. WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) I PAGE (31 Salem Generating Station TITLE (4)

- Unit 2 o 1s 10*10101 31111 1foF 01 5 ESF Signal Actuation:: Contt~ I Room Vent. Switch To Erner. Mode Due To *Personnel Error

• EVENT DATE (51 LER NUMBER (6) REPORT DATE (71 OTHER FACILITIES INVOLVED (81

~t~t~ ~)?~ NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACILITY NAMES DOCKET NUMBER(SI NUMBER 0 I 5 IO I O I O I I I ol 3 ii 5 9 2 912

- ol ol 4

- 0 ~ q4 113 912 6 I5 I0 I 0 I 0 I I I OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE RcOUIREMENTS OF 10 CFR §: (Chock OM or moro of tho following} (111 MODE (81 5 20.402(bl

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20.405(cl . ,_x 60,73(1J(2)(iv)

....;.....

73.71(b)

'POWER LEVEL (10) Io,o ,o ,__.:. 20.4051*111 )(i) 20.405(1)(1 )(ii)

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50.38(c)(11 50.36(cll2l

- 60.73(1J(2)(v) 50.73(1)(2J(viil

.,.._ 73.711cl OTHER (Specify in Absrract

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'--- 1-- bslow snd in Text, *NRC Form 20.405(0)(1 )(iii) 50.73(1J(2J(i) &0,73(1112l(viiil(AI 366A}

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20.405(1 )(11 (Iv) 60.73(1)(2)(iil 50.73(1J(2J(viiiJ(BI

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20.40511l11lM 50,73(1J(2)1iiil 50.73(1)(2llxl LICENSEE CONTACT FOR THIS LEA (121 NAME TELEPHONE NUMBER AREA CODE

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M. J. Pollack - LER Coordinator 61 019 3 I 3 I 9 1-* I 2 I 0 I? I 2 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

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CAUSE SYSTEM COMPONENT MANUFAC*

TUR ER REPORTABLE It?/:{/:??????.

TO NPRDS 1*:*:*:*:*:*:*:*:::*:*:*:*:*:::*:*:*:*:-:*:*:*:*:*:*:* CAUSE SYSTEM COMPONENT MANUFAC*

TUR ER REPORTABLE -:-::-:- *:*:*:*:* -:*: :-:-:-:-:

TO NPRDS :-:--:-::-:-: -:*: :::::::::

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SUPPLEMENTAL *REPORT EXPECTED (141 MONTH DAY YEAR EXPECTED n YES !If vas. complateEXPECTED SUBMISSION DATE}

ABSTRACT (Limit to 1400 spaces, i.e .. approximately fifteen single-space typewritten lines) 116) hi NO SUBMISSION DATE (151 I I I On 3/15/92, the 2B4D 4KV breaker tripped open on "phase c time overcurrent" upon starting the No. 24 Containment Fan Coil Unit. This de-energized the 2B-460 VAC and the 2B 230 VAC Vital. Busses. With the loss of the 2B 460 VAC Vital Bus~* the 2R1B Radiation Monitoring System (RMS} channel de-en~rgize~ and caused a signal for Control Rqom Ventilation Switch to the Emergency Mode of Operation (both Units} at 2305 hours0.0267 days <br />0.64 hours <br />0.00381 weeks <br />8.770525e-4 months <br /> (per design) . This signal is an Engineered Safety Feature.

The root cause of this event is. personnel *error, as attributed to _poor work practice. Relay department personnel did not comply with reasonable self-verification work practices. .On 1/11/92, Relay

• Department personnel removed the 2B 460 VAC and 230 VAC Vital Buss es overcurrent relays in support of r1:>utipe maintenance and calibration.

Upon completion, the relays were placed back in the bus; however, 4 of the six (6) relays were put into the wrong Bus. Corrective disciplinary. action* has. been taken with the l.ndividuals involved. This event bas been reviewed with applicable Relay Department personnel.

The other 460 and 230 VAC Vital Bus relays were inspected. No additional discrepancies were identified. Revision of applicable Relay Department and Maintenance Department procedures has been initiat~d to require verification of relay installation. *This event will be reviewed by the Nuclear Training Center for incorporation into continuing training programs as applicable. The 2R1B RMS channel was returned to service following satisfactory verification of operation.

NRC Form 366 (6-891

LICENSEE EVENT REPORT. (LER) TEXT CONTINUATION Salem Generating Station .DOCKET NUMBE~ LER NUMBER PAGE

. _U_n_i_t_2_ _*-----------------"-5000,-"3~1~1o.__ _ _--=9:-=2=----=0_Q_4_-_Q_0.~-----=2=-- of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurize.d Water Reactor Energy Industry Identification System (EIIS) codes are .identified in the. text as {xxl.

IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature. signal actuation for Control Room Ventilation switching due to personnel error Discovery Date~* 3/15/92 Report Date: 4/13/92 This_ report was initiated by Incident Report No ..91-186.

CONDITIONS PRIOR TO OCCURRENCE: ---

1/11/92 - Mode* 6, Gt h

• Refueling Outage in Progress 3/15/92 Mode 5 DESCRIPTION OF OCCURRENCE:

On March 15, 1992, at 2242 hours0.0259 days <br />0.623 hours <br />0.00371 weeks <br />8.53081e-4 months <br />, 4KV.breaker 2B4D tripped open ori "phase C time* overcurrent".

• This breaker feeds the 2B 460 VAC and the 2B 230 VAC Vital Busses. At the time of the breaker trip, 24 Containment ~an Coil Unit {BK} was being started (in high speed).

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Witn the loss of the 2B 460 VAC *vital Bus, the No... 22 RM Distribution panel de-energized. The 2R1B Radiation Monitoring System (RMS} {ILi channel is* powered via the No. 22 RM Distribution panel. A new UPS was installed* during the current refueling outage which includes a self* contained battery. DC power supplied to the inverter allowed the 22 RM Distribution Panel to remain energized. Wilen the battery voltage decayed to 105 VDC the inverter automatically shutdown (per design} . Consequently, de-eri.ergization of the 2R1B RMS channel .

caused a signal for Control Room Ventilation Switch to the Emergency

• Mode of Operation (both Units) .at 2305 hours0.0267 days <br />0.64 hours <br />0.00381 weeks <br />8.770525e-4 months <br /> (per design). This signal is an Engineered Safety Feature. Therefore, the Nuclear Regulatory Commission. was notified on March 15, 1992, at 0008 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />s-in accordance with Code of Federal Regulations 10CFR 50.72(b)(2) (ii)

APPARENT CAUSE OF OCCURRENCE:

. .

The root.cause of this event is personnel error, as attributed to poor work practice. Relay department personnel did not comply with

~easoriable self-verifi6ation work practices.

On January 11, 1992, Relay Department personnel removed the 2B 460 VAC and 230 VAC Vital Busses phase A and.phase C overcurrent relays in support of routine maintenance and 6alibrati6n. Normally, these relays are removed one at a time and calibrated at the job site.

Salem Generating Station

• DOCKET NUMBER

• LICENSEE EVENT REPORT (LER} TEXT CONTINUATION LER NUMBER PAGE u==ri=i~t'-----"2;:.._~~~~~~~~~~~~~~s~o~o~o=J=l=l=---~~~~=9=2~-004-qp~*~~~J~qf~S~~

APPARENT CAUSE OF OCCURRENCE: (corit'd}

• However, due to significant.work activity in the area, it was decided to remove all' th~ relays and calibrate them at a different location.

The relay serial numbers were recorded as to th~ir bus location.

After completing the calibration, the relays were placed back in the bus. Four (4) of the six (6) relays were put into* the wrong* Bus_ -

(i.e. 230 VAC vs. 460 VAC}. The Relay Department technicians did not verify that each relay was returned to its original location._ The paper work identifying this information* had been left at the calibration location during reinstallation of the relays.

ANALYSIS OF OCCURRENCE:

The 2R1B_channel continuously monitors air from the HVAC intake duct into the Unit 2 Control Room. When the alarm setpoint is reached, the monitor actuates an alarm initiating closure of the duct intake valve to prevent cqntaminated air from entering the Control Room (both Salem Units). By design, channel loss of power actuates its ESF function~

The .2R1B channel functioned as designed when *it lost power. Since Control Room ventil*ation system* switching. to the accident* mode of operation is an ESF actuation; this event is reportable to the Nuclear Regulatory* Commission in accordance with Code of Federal Regulations 10CFR S0.73(a) (2) (iv).

An assessment, by System Engineering, of the safety consequences of the 2B 230 VAC Vital Bus relays and the 2B 460 VAC Vital Bus relays being switched was conducted.

Under these conditions, 2B 460 VAC Vital Bus time overcurrent protection had a decreased pickup setpoint of 120A (4KV side)'in lieu of its normal 300 amp setpoint. The new setpoint made breaker 2B4D trip sensitive when starting large motors such as the CFCUs in high speed (300 HP) with the. bus already loaded. Although the CFCUs are not required in Mode 5 or 6,. they would still receive a low speed

- (100 HP) st~rt signal from the Safeguards Equipment Control (SEC)

Cabinet fJCI load sequencer in the event of a design basis.iccident.

The SEC and SSPS are not required to be operable in Modes 5 and 6; although, they are kept functional.

• The 2B 460 VAC Vital Bus was required to be operable between February 4, 1992 and March 3, 1992 during which time the No. 2A Vi ta:l .Bus electrical trains were removed from service for maintenance. In Modes 5 and 6, only two (2) of the three (3) Vital Bus electrical trains are required per Technical Specification 3.8.2.2. During this period, the 2B 460 VAC Vital Bus loads continuously energized included:

No. 22 Spent Fuel Pump (lOOHP)

No. 22 Auxiliary Building Exhaust Fan (75HP)

No. 22 Auxiliary Building Supply Fan {SOHP)

No. 22 Fuel Handling Are~ Fan (20 HP)

No. 22 RM Distribution Panel (10 KVA)

• **

LICENSEE EVENT REPORT (LER) .TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE u_~n~i_t~2~~~-*~~~~~~~~~--"s~o~o~o~3~1=1~-~~---,~~92-004-00 4 of 5 ANALYSIS OF OCCURRENCE: (cont'd)

The No. 24 CFCU was not started until March-15, 1992 when this event occurred. The oth~r two (2) major loads include the No. 22 Chiller (100 HP) and the.No. 22 CFCU. They were cleared and tagged during this period in support of maintenance activity. Therefore, had a "mode op" condition occurred, only the No. 24 CFCU.would start (in low speed) and would not have. caused the 2B4D breaker to trip.

Th.e 2B 230 VAC Vital Bus overcurrent protection relay was raised from 80 t~ 20.0 amps (4KV side) when the relays* were swapped. The bus would have supplied* power, during an emergency, to its associated

.loads. However, it would have been affected if the 2B 460 VAC Vital Bus had tripped on overcurrent since both transformers are fed from the same 4KV breaker. Therefore, the operation of this bus was also dependent on the 2B 460 VAC Vital Bus operation which was found acceptabl~ as described above.

Based on the above discussion, the health and Safety of the public was not affected by this event since the 2B 460 VAC and 230 VAC Vital Busses remained functional even though the overcurrent protection re rays were switched. *

• Technical Specification 3.8.2.2 states:

"As a minimum, two A.C. electrical bus trains shall be OPERABLE and eneigized from sources of power other than a diesel generator but aligned to an OPERABLE diesel generator with each train consisting.of:

1 - 4 kvolt Vital Bus 1 - 460 volt Vital Bus and associated control centers 1 - 230 volt Vital Bus and associated control centers 1 - 115 *volt Instrument Bus energized from its respective inverter connected to its respective D.C. Bus Train."

CORRECTIVE ACTION:

Appropriate corrective disciplinary action has* been taken with the individuals involved in this event.

This event has been reviewed with applicable Relay Department personnel.

The other 460 and 230 VAC Vital Bus relays for the Unit 1 busses and the other Unit 2 busses were inspected and verified as to their required settings. No additional discrepancies were identified.

Revision of applicable ~elay Departmeht and Maintenance Department procedures has been initiated to require verification of relay installation.

This event will be reviewed by the Nuclear Training Center for incorporation into continuing training programs as applicable.

• .Salem Generating Station

• DOCKET NUMBER

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

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LER NUMBER PAGE

_U_n_i_t_2_ _ _ _ _ _ _ _ _ _ _ _ _ _5000311_____ 92-Q_Q_4-Q_Q~-- 5 of--*-----*

-- -*-*-- 5 CORRECTIVE ACTION: (cont'd)

The 2R1B RMS channel was returned to service following satisfactory verification of* operation.

Gener 1 Manager -

Salem Operations MJP:pc SORC Mtg.91-044