ML18096B266

LER 93-001-00:on 921209,under-frequency Protection for 2H 4 Kv Group Bus Unknowingly Inoperable Due to Mispositioned Test Switch.Caused by Personnel Error.Group Uv & Uf Monthly Procedures Will Be revised.W/930209 Ltr

ML18096B266
Person / Time
Site:	Salem
Issue date:	02/09/1993
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-001-01, LER-93-1-1, NUDOCS 9302170241
Download: ML18096B266 (5)

Text

e PS~G-Public Service Electric and Gas Companv P.O. Box E Hancocks Br*idge, r\Je*:,* Jersey 08038 Salem Generating Station February 9, 1993

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 93-001-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR

50. 73 (a) (2) (i) (B). This report is required to be iss~ed within thirty (30) days of event discovery.

Sincerely yours,

/;/fl/4,

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c. A. Vondra General Manager -

Salem Operations MJP:pc.

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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: so.a HRS. FORWARD

.LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS

~ AND REPORTS MANAGEMENT BRANCH (P-5301. U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT 13150-0104), OFFICE i

OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME 11 I DOCKET NUMBER (2) I PAGE 13)

Salem Generating Station - Unit 2 o 1s101010131111 1 OF 0 14 TITLE 141 2H 4KV Group Bus UF Protection Inop. Due* *To Mispositioned Relay Test Switch EVENT DATE (5) LEA NUMBER 161 REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR kt SEQUENT JAL NUMBER k< REVISION NUMBE A MONTH DAY YEAR FACILITY NAMES DOCK_ET NUMBERIS) o1s1010101 I I 11 2 q9 9 2

- - q2 913 o lo I 1 o I o ol9 91 3 o1s1010101 I I THIS REPORT IS SUBMITTED PURSUANT TO THE R~OUIREMENTS OF 10 CFR §:(Check one or more of the following) (111

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                                                                                                                                                                              -    50.73(11121 lviiillBI 50.7:il1112llxl NAME                                                                                                                                                                                   -                               TELEPHONE NUMBER AREA CODE IM. J. Pollack - LER Coordinator                                                                                                                                                                           6 10 I 9 3 I 31 9 I                  I 21 o 12 I 2 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 1131
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                                                                  -                                                                                                                                                                MONTH               DAY                    YEAR SUPPLEMEN_TAL REPORT EXPECTED (141 EXPECTED l               YES (If yes. complete EXPECTED SUBMISSION DATE; ABSTRACT (Limit to 1400 spaces. i.e., appro_ximately fifteen single-space typewritten lines) 116) hi                 NO SUBMISSION DATE 1151 I                    I                        I From 12/9 /92, until discovery at 1100 hours on 1/12/93, under-frequency (UF) protection for 2H 4KV Group Bus was unknowingly inoperable due to the bus UF relay test (knife) switch being left in the "OPEN" position following the monthly under-voltage (UV)/UF surveillance test of the bus. The Technical Specification (T/S) Action Statement was entered.

The. subject relay test switch is located in locked electrical cubicle 2HAD. The 2H 4KV Group Bus monthly surveillance was completed at 1317 hours (same day) (including closure of the test switch) ; thereby, the Action Statement was exited. The root cause of this event is personnel error due to a-technician's failure to comply with a surveillance procedure. The procedure requires closing the subject test switch following testing and to "ENSURE" that all 2H Group Bus UV and UF test switches are closed. Disciplinary action has. been taken with the technician involved with the 12/9/92 surveillance of the 2H Bus UF relay. This event has been reviewed by Maintenance Department management and will be reviewed with applicable department personnel. The Group Bus UV and UF monthly functional test surveillance procedures will be revised to provide for independent verification of the test switch closure. NRC Form 366 16-89)

LI.CENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-001-00 2 of 4 PLANT AND SYSTEM IDENTIFICATION: Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as {xx} IDENTIFICATION OF OCCURRENCE: INOPERABILITY OF 2H 4KV GROUP BUS UNDER-FREQUENCY PROTECTION DUE TO MISPOSITIONED (OPEN) UNDER-FREQUENCY RELAY TEST SWITCH Event Date: 12/09/92 Discovery Date: 01/12/93 'Report Date: 02/9/93 This report was initiated by Incident Report No. 93-024. CONDITIONS PRIOR TO OCCURRENCE: Mode 1 Reactor Power 100% - Unit Load 1170 MWe DESCRIPTION OF OCCURRENCE: From December ~' 1992, until January 12~ 1993, under-frequency (UF) protection for 2H 4KV Group Bus was unknowingly inoperable. This occurred due to the bus UF relay test (knife) switch being left in the "OPEN" position following the monthly *under-voltage (UV)/UF surveillance test.of the bus, performed under procedure S2.MD-FT.4KV-Q007(Q), "REACTOR TRIP SYSTEM MONTHLY FUNCTIONAL TEST - 2H GROUP BUS RCP (Reactor Coolant Pump) UNDER VOLTAGE & UNDER FREQUENCY". Event discovery occurred on January 12, 1993, at 1100 hours, during the subsequent performaDce of the surveillance. The subject relay test switch is located in locked electrical cubicle ~HAD. Immediately after event discovery, Operations supervision was notified a'nd Technical Specification (T/S) 3.3.1.1 Action 6 was entered. The 2H 4KV Group Bus monthly surveillance was then completed at 1317 hours (same day) (including closure of the test switch); thereby, the Action Statement was exited. T/S 3.3.1.1 Action 6 requires the following:

    "With the number of OPERABLE channels one less that the Total Number of Channels, STARTUP and/or POWER OPERATION may proceed provided the following conditions are satisfied:

a. The inoperable channel is placed in the tripped condition within 1 hour.

LICENSEE. EVENT REP.ORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER. LER NUMBER PAGE Unit 2 5000311* 93-001-00 3 of 4 DESCRIPTION OF OCCURRENCE (continued):

b. The Minimum Channel OPERABLE requirement is met: however; one additional channel may be bypassed for up to*2 hours for*

surveillance testing per Specification 4.3.1.1. 11 The 2H 4KV UF relay is a GE Type SFF21A relay, which detects UF on power circuits. This relay has one Normally Open (NO) . (contact used) and one. Normally Closed (NC) output contact which changes state only when the relay setpoint is reached {bF condition) and it is sensing at least 50% of rated voltage. When the relay is deenergized (test switch open), the relay output contact will not change state and the 2H RCP Group Bus UF Reactor Trip signal is disabled. .In addition,* the associated Control Room annunciator for an UF condition on the 2H bus is also disabled ~hen the test switch is open. Th.J.s event is reportable due to non-compliance with T/S 3.3.1.1 Action 6, per Code of Federal Regulation 10CFR 50.73(a) (2) (~) {B). APPARENT CAUSE OF OCCURRENCE: The root cause of this event is personnel .error due to the responsJble . techniciari failirig to close the relay test switch in accordance* with the subject surveillance procedure. *Procedure step 5.3.19 requires closing the subject.test switch following testing and step 5.4.3 specifi~s to "ENSURE" that all 2H Group Bus UV and UF test sw.itches are closed. Step 5.4.4 then follows, which requires closure and lockup of the involved 2HAD Group Bus cubicle door. These cubicle doors are maintained locked as a corrective action to a prior similar occurrence on Salem Unit 1

*(reference LER ~72/87-005-00, dat.ed May 22, 1987).

Inve~tigation of this event included review of the December 9~ 1992 surveillance performance documentation as well as interviews with the involved techniciaris. ANALYSIS OF OCCURRENCE: With th~ subject test switch open, a UF condition on the 2H Group 4KV Bus would. not be sensed by the Reactor Protection System {JC}. The UF trip and the UV trip provide core protection against departure from nucleate boiling resulting from a UF condition at more than one Reactor Coolant Pump {AB}. The UF trip assures a Reactor Trip before a low Reactor* Coolant System (R.CS) flow condition develops~. The logic for the trip generation requires a UF condition on either 2F or 2G Group Bus _in coincidence with a UF condition on either the 2E or 2H Group Bus. A failure of the 2E bus UF protection with the 2H bus UF protection defeated would have prevented an automatic RCP trip signal upon an UF .. condition. However, core Frotection again~t a loss of flow condition would $till be available by the Reactor Coolant System loop flow logic. With-the exception cif an approximate 30 minute inoperability of the 2E bus UF relay-on January 12, 1993, an UF Reactor Trip signal would have

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 93-001-00 4 of 4 ANALYSIS OF OCCURRENCE (continued)'.: beeri initiated upon an UF condition as sensed by the 2E, 2F, and 2G bus UF relays. The 2E UF relay inoperability occurred during the respective monthly UV/UF surveillance testing of the 2E bus UF relay per *

.S2.MD-FT.4KV-0004(Q). Had an UF condition occurred on the 2F or 2G buses when the 2E and 2H UF relays were inoperable, an UF alarm annunciation would have actuated to alert the .control Operator to manually initiate a Re~ctor Trip signal. In addition, the RCP Group Buses are also provided with UV protection. A check of the unit main generator frequency recorder (XA-8846), for the subject time period, did not show evidence of an UF. condition.

The PSE&G electrical distribution system is fed from the 500 kV grid (infinite bus) and will automatically (instantaneously) load shed when system frequency drops to 59.3 Hz to maintain normal grid frequency. Should grid frequency decrease to 57.55 Hz, the applicable Abnormal Operating Procedure requires a manual Reactor trip. The 4 kV Group Bus UF*relays' setpoint is 57.5 Hz, while the minimum allowable setpoint is 56.4 Hz, as per T/S. This event did not affect t~e health and safety of the public. This is based upon the means available for detection of and responding to an UF condition on the RCP Group buses throughout the time period of the 2H Bus UF detection inoperability. CORRECTIVE ACTION: Disciplinary action has been taken with the technician involved with the December 9, 1992 surveillance testing of the 2H Bus UF relay. This event has been reviewed by Maintenance Department management and will be reviewed with applicable department personnel. The Group Bus UV and UF monthly functional test surveillance procedures

 ~ill  be revised to provide for independent verification of the test switch closure.
                                              , / / 4///{

b~t~//~~- General Manager - Salem Operations . MJPJ:pc SORC Mtg. 93-013}}