ML19031A905

LER 1977-045-03 for Salem Unit 1 Inoperability of Transmission Line Due to Flashover Relay Operation

ML19031A905
Person / Time
Site:	Salem
Issue date:	07/19/1977
From:	Librizzi F Public Service Electric & Gas Co
To:	O'Reilly J NRC/IE, NRC Region 1
References
LER 1977-045-03
Download: ML19031A905 (5)

Text

Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201 /622-7000 July 19, 1977 Mr. James P. O'Reilly Director of USNRC Off ice of Inspections and Enforcements Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Mr. O'Reilly:

LICENSE NO. DPR-70 DOCKET NO. 50-272 REPORTABLE OCCURRENCE 77-45/03L Pursuant to the requirements of Salem Generating Station Unit No. 1 Technical Specifications, Section 6.9.1, we are submitting Licensee Event Report for Reportable Occurrence 77-45/03L. This report is required within thirty (30) days of the occurrence.

Sincerely yours,

~-~£*

F. *P. Lib~

General Manager -

Electric Production CC: Director, Office of Inspection and Enforcement (30 copies)

Director, Office of Management Information and Program Control (3 copies)

- - - - - - --*,\

I 772070014 Tile Energy People

Report Number:

Report Date:

e77-45/03L

. 7/08/77 Occurrence Date: 6/26/77 Facility: Salem Genera~ing Station Public Service Electric & Gas Company Hancocks Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

Loss of 5024, 500kV Transmission Line CONDITIONS PRIOR TO OCCURRENCE:

Operational Mode 1, Reactor Power 100%, 100% Generator Trip Test in progress.

DESCRIPTION OF OCCURRENCE:

At 1013 am, during the conduct of the 100% Generator Trip Test, the 5024, 500kV transmission line became inoperable due to operation of the Bus Section 1-5 and 5-6 Breaker Flashover Relay (NCHllA) and its associated HEA Relay. Technical Specification Action Statement for LCO 3.0.1.1 was implemented and Surveillance Procedures 4.8.1.1.1.a and 4.8.1.1.2.a.2 were performed. At 1454, the 5024 transmission line was re-energized and Action Statement 3.8.1.1 was terminated.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

Bus sections 1-5 and 5-6 generator breaker flashover protection HEA relay is tripped after 13 cycles time delay by either the #1 Unit main power transformer ground relay (PJCllAV) or the bus sections 1-5 and 5-6 breaker flashover relay (NHCllA) if the auxiliary switch contacts on both bus sections 1-5 and 5-6 breakers indicate that these breakers are open. When Salem No. 1 .Unit is operating at 100% load, the PJCllAV is de-energized. It picks up at 480 amperes of main power transformer ground current. The NHCllA is energized, because it is connected to the generators output current transformers and is set to pickup at 7000 generator amps which is about 23% of rated generator load.

The transient data recorder showed that after bus sections 1-5 and 5-6 breakers opened, the No. 1 Unit generator current rerna~ned for more than 13 cycles at or above 8000 amperes due to the transformer exciting current resulting from the momentary rise in voltage on the generator as a result of the load rejection. Therefore, the NHCllA relay remained energized and in 13 cycles tripped the associated HEA relay, isolating the 5024 line at the station and at the New Freedom switching station.

Report No. 77~45/03~ 7/8/77 ANALYSIS OF OCCURRENCE:

Technical Specification Action Statement 3.8.1.1.a*allows 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore an inoperable offsite circuit to operable status. The 5024, 500kV transmission line was restored to operable status in 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and 41 minutes, therefore, there was no violation of the Technical Specifi-cations.

CORRECTIVE ACTION:

The bus section 1-5 and 5-6 breaker flashover NHCllA relay has been withdrawn from service for the following reasons:

1. Adequate protection against either generator breaker flashover is provided by the flashover relays connected to current trans-formers located at each generator breaker.

2. Main power transformer ground relay provides redundant protection against one or two phase and/or phase to ground flashover.

3. Due to the unpredictability of the residual current value in the generator - main power transformer circuit, the setting for the NHCllA which would prevent false tripping may be too high to provide effective protection under all operating conditions. In addition, this protection is redundant.

4. A false nuclear unit trip is not offset by the questionable benefit of the redundant protection provided by the NHCllA.

FAILURE DATA:

This event did not involve equipment failure.

Prepared by T. Spencer

~~~~~~~~~~~-

I .

Manager - Salem Generating Station SORC Meeting No. 75-77

~~~~~~~~-

LER 77-45/03L 7/8/77 LICENSEE EVENT REPORT-CONTROL BLOCK I* I 6

LICENSEE LICENSE EVENT NAME LICENSE NUMSER TY!'E TYPE

@]!]IN I JI SIG IS 111 9 14 Js° Io 1-1 o Io Io Io Io 1-1 ~I gJ ' l ~. * *

~4 I 1J 11 11 l:Jo ~

REPORT REPORT *-* "' -

CATEGORY TYPE SOURCE OOCKET NUMSER EVENT CATE REPORT CATE roTil coN*TLJ_J llJ u:.J I 0 I 51 0 I -I 0 I 2 I 71 21 I 0 16 12 16 F 17 I I 0 I 71 11 0 17 I 7J j1 57 58 :is so s1 ea 69 74 75 EVENT oescmPTION

@li] I During conduct of 100% Gen. Trip Test, the 5024, 500kV Transmission line I i 7 8 9 so

@TI] became inoperable due to flashover relay operation. The 5023 line and all 7* 8 9

~ diesel generators were operable. Relay was withdrawn from service to pre-7 8 9

[Q]iJ I vent reoccurrence. This is the first occurrence of this type. (77-45/03L) I 7 8 9 SI) 7~8~9----------------------------------PR_l_M_E------------------------------------------00~

SYSTEM CAUSE COMPONENT COMPON!::NT

. COOE COOE COMPONENT CODE SUPPLIER MANUFACTURER VIOLATION

@TIJIEIAI lKJ IZIZIZ!ZIZ_LEJ U!J I Z I 91 9 ! 9 I ~

_7 8 9 10 11 12 17 43 44 47 48 FACILITY METHOO OF STATUS °""POWER OTHEfl STATUS DISCOVERY DISCOVERY pESCRl?TION ITEla 1

LBJ.

9

• 1110 10 I 10 12 1~~-N~;~,A~~---'I 13 44

@j 45 N;A 80 FORM OF ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE

~

7 8 9

~

10 11 w I N/A 44 I45

.. N/A PERSONNEL EXPOSURES NUMBER TYPE OESCRIPTION 7!2E)!O 89 1010

. 11I IZj 12 ~ 1 3 < " " - "

N A

_______:;..;,.L-;;..:;__..._______________________________________________ 8 0 ~

PERSONNEL INJURIES NUMBER DESCRIPTION GE]1010101 N A 7 & 9 11 12 80

µEl .

OFFSITE CONSEQUENCES N A LOSS OR DAMAGE TO FACILITY G:@ lg;"j i°ESCRIPT!ON N/A 7 8 10 NAMe: ____________....:T::....:.*--=L::...:.'--=S=-o~e:..:n=c'-"'e=-=r=------- PHONE: (609) 365-7000 Ext. Salem 528

• <I * ..

19"/l JUL 25 PM 12 00