ML18102A544

LER 96-012-00:on 961005,two Potential Transformer Fuses Opened While Performing an Electrical Test of 21 Svc Water Pump.Cause Unknown.Work Practices for Specialized Electrical Testing Will Be Reviewed for adequacy.W/961104 Ltr

ML18102A544
Person / Time
Site:	Salem
Issue date:	11/04/1996
From:	Garchow D, Hassler D Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-96-012-02, LER-96-12-2, LR-N96351, NUDOCS 9611130481
Download: ML18102A544 (5)

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Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit NOV 041996 LR-N96351 U. S. Nuclear Regulatory Commission Document Control Desk WashingtOn, DC 20555 LER 311/96-012-00 SALEM GENERATING STATION - UNIT 2 FACILITY OPERATING LICENSE NO. DPR-75 DOCKET NO. 50-311 Gentlemen:

This Licensee Event Report entitled "Engineered Safety Feature Actuation, 2A 4kV Vital Bus Undervoltage" is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR50.73 (a) ( 2) (iv) .

Sincerely, Jid.r;t_p, }J 0-

~~~;d F. Garchow General Manager -

Salem Operations Attachment DVH c Distribution LER File 3.7 1 * :. ,: (': ii:i 1

'- 1  ; .. .:

9611130481 961104 PDR ADOCK 05000311 S PDR The pov:er is b your hands.

95-2168 REV. 6/94

Document Control Desk LR-N963510 Attachment A The following represents the commitments that Public Service Electric Gas (PSE&G) made to the Nuclear Regulatory Commission (NRC) relative to this LER (311/96-012-00). The commitments are as follows:

1. The 2A bus was re-energized on October 8, 1996.

2. The work practices for specialized electrical testing will be reviewed for adequacy including the need to use fused test equipment. This review will be completed prior to Salem Unit 2 entering Mode 6.

3. To address the concern with the design of the undervoltage relay circuitry, a label will be installed on the 4kV voltmeter switches to caution against using the switch in the event of an existing 1 out of 3 undervoltage relay trip. This will be completed by November 28, 1996. In the interim, a Operations Department night order has been issued to advise the operating crews of this concern.

NRCFORM366 U.S.N AR REGULATORY COMMISSION OVED BY OMB NO. 3150-0104 (4-95) EXPIRES 04/30198 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 60.0 HRS.

REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSEE EVENT REPORT (LER) LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T-6 F33), U.S. NUCLEAR (See reverse for required number of REGULATORY COMMISSION, WASHINGTON, DC 2055~. AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF digits/characters for each block) MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) uu ... KET NUMBER (2) PAGt:.(")

SALEM GENERATING STATION UNIT 2 05000311 1 OF 3 TITLE(4)

Engineered Safety Feature Actuation, 2A 4kV Vital Bus Undervoltage EVENT DATE (5) LER NUMBER (6) RE;->ORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR I SEQUENTIAL NUMBER IREVISION NUMBER MONTH DAY YEAR FACILITY NAME DOCKET NUMBER FACILITY NAME DOCKET NUMBER 10 05 96 96 - 012 - 00 11 04 96 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Checkoneormore) (11)

N MODE (9) 20.2201(b) 20.2203(a)(2)(v) 50. 73(a)(2)(i) 50. 73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)(i) 50. 73(a)(2)(ii) 50. 73(a)(2)(x) 000 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) x 50. 73(a)(2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50. 73(a)(2)(v) Spec~in Abstract below or in C Form 366A 20.2203(a)(2)(iv) 50.36(c)(2) 50. 73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Area Code)

Dennis v. Hassler, LER Coordinator 609-339-1989

~

COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS TONPRDS I

I SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR SUBMISSION

'YES (If yes, complete EXPECTED SUBMISSION DATE). XINO DATE (15)

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

On October 5, 1996 while performing an electrical test of the 21 service water pump, two potential transformer fuses opened. The control room received an alarm at 1548 hours0.0179 days <br />0.43 hours <br />0.00256 weeks <br />5.89014e-4 months <br /> that one of three undervoltage relays tripped. Subsequently, operators attempted to read all three phase 4kV voltages at the local panel voltmeter. There is a single voltmeter installed and a selector switch is used to connect the voltmeter to any combination of phase to phase voltages through two potential transformers. When the switch was turned from phase A-B to A-C, a second undervoltage relay actuated at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />. The second relay actuation initiated the Safeguards Equipment Controller and started the 2A Emergency Diesel Generator (EDG) .

The cause of the first undervoltage condition could not be determined. The second undervoltage relay actuation was caused by a design problem in the undervoltage relay circuitry which is only applicable when one potential transformer has open fuses. Corrective actions include a review of the work practices for electrical testing, and installation of a label to caution against use of the voltmeter switch in the event a one out of three undervoltage condition exists.

This event is reportable under 10 CFR 50.73(a) (2) (iv), actuation of an Engineered Safeguards Feature (ESF).

NRC FORM 366 (4-95)

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 0 5 0 0 0 311 YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 2 OF 3 SALEM GENERATING STATION UNIT 2 96 - 012 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PLANT AND SYSTEM IDENTIFICATION Westinghouse - Pressurized Water Reactor 4KV Vital Bus {ED/-}*

Emergency Diesel Generators {EK/-}

• Energy Industry Identification System (EIIS) codes and component function identifier codes appear as {SS/CC}

CONDITIONS PRIOR TO OCCURRENCE At the time of occurrence, Salem Unit 2 was shutdown and defueled.

DESCRIPTION OF OCCURRENCE In early 1996, Design Change Packages (DCP) were initiated to replace all Salem Unit 2 Service Water pumps and keep the existing motors. The new pumps were installed in February 1996 and initially run to attain operability. Final acceptance required testing the electrical load on the service water motors to determine if the expected increased efficiency of the pumps was realized. The installation testing included steps to measure the amperage draw of the new motors to determine if there was a power savings associated with the replacement pumps.

On October 5, 1996 while performing an electrical test of the 21 service water pump, two potential transformer fuses open circuited. The control room received an alarm at 1548 hours0.0179 days <br />0.43 hours <br />0.00256 weeks <br />5.89014e-4 months <br /> that one out of three undervoltage relays tripped.

Subsequently during actions to investigate the initial undervoltage condition, operators attempted to read all three phase 4kV voltages at the local panel voltmeter. A single voltmeter is installed and a selector switch is used to connect the voltmeter to any combination of phase to phase voltages through two potential transformers. When the switch was turned from phase A-B to A-C, a second undervoltage relay actuated at 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br />. The second relay actuation initiated the Safeguards Equipment Controller (SEC) and started the 2A Emergency Diesel Generator (EDG). The start of the EDG constituted an Engineered Safeguards Actuation.

NRC FORM 366A (4-95)

NRC FO~M 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05000311 YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 3 OF 3 SALEM GENERATING STATION UNIT 2 96 - 012 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PRIOR SIMILAR OCCURRENCES A review of LERs for the past two years did not identify any similar occurrence of an undervoltage condition, or testing that resulted in an ESF actuation.

However, LER-272/91-022-00 reported an ESF actuation involving an undervoltage condition on the lB and lC buses and a subsequent EDG start. The lB event was similar to this event in that a one out of three undervoltage condition occurred. During subsequent trouble shooting, a second undervoltage condition occurred as a result of the change in the voltmeter switch position. However, the LER did not address the voltmeter switch change as a cause. The LER focused on the initial undervoltage condition which occurred during a monthly undervoltage functional surveillance. The LER corrective actions involved a design change of the cubicle and personnel actions.

CAUSE OF OCCURRENCE The root cause of the first undervoltage relay actuation could not be determined. The electrical test equipment was thoroughly tested by PSE&G and the vendor of the test equipment eliminating the test equipment as the cause of the occurrence. The PT, UV relays and installed wiring were also inspected with no evidence of any faults or damage. Investigation also determined that personnel errors could not be substantiated.

The cause of the second undervoltage relay actuation is attributed to the design of the undervoltage relay circuitry when one potential transformer has open fuses.

SAFETY CONSEQUENCES AND IMPLICATIONS Salem Unit 2 was defueled at the time of the event. The 2A Vital Bus undervoltage protection functioned as designed. The SEC received a bus undervoltage signal resulting in the successful blackout loading of the 2A Vital Bus. The 2A D/G started and loaded per design. Therefore, this event did not affect the health or safety of the public.

CORRECTIVE ACTIONS

1. The 2A bus was re-energized on October 8, 1996.

2. The work practices for specialized electrical testing will be reviewed for adequacy including the need to use fused test equipment. This review will be completed prior to Salem Unit 2 entering Mode 6.

3. To address the concern with the design of the undervoltage relay circuitry, a label will be installed on the 4kV voltmeter switches to caution against using the switch in the event of an existing one out of three undervoltage relay trip. This will be completed by November 28, 1996. In the interim, an Operations Department night order has been issued to advise the operating crews of this concern.

NRC FORM 366A (4-95)