ML18066A378

LER 98-013-00:on 981222,safeguards Transfer Tap Changer Failure Caused Inadvertant DG Start.Caused by Failed Motor Contactor.Contactor Was Replaced.With 990120 Ltr

ML18066A378
Person / Time
Site:	Palisades
Issue date:	01/20/1999
From:	Dotson B, Thomas J. Palmisano CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-98-013, LER-98-13, NUDOCS 9901270015
Download: ML18066A378 (3)

Text

A CMS Energy Company Palisades Nuclear Plant Tel."616 164 2296 21180 Blue Star Memorial Highway Fax: 616 164 2425 Covert, Ml 49043

'lllotu* J. l'allllluao Site Vice President January 20, 1999 U.S. Nuclear Regulatory Commission A TIN: Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE PPR PALISADES PLANT LICENSEE EVENT REPORT 98-013, SAFEGUARDS TRANSFORMER TAP CHANGER FAILURE CAUSES INADVERTENT DIESEL GENERATOR START.

• . Licensee Event Report (l-ER)98-013 is attached. The LER describes an event where a malfunction of the Safeguards Transformer automatic tap changer resulted in an undervoltage condition on 2400 volt Buses 1C and 1D which actuated both emergency diesel generators.

This event is reportable to the NRC in accordance with 10 CFR 50.73(a)(2)(iv) as a condition that resulted in an automatic actuation of an engineered safety feature.

SUMMARY

OF COMMITMENTS This letter contains rio new commitments and no revisions to existing commitments.

-~~)°~

Thomas J. Palmisano Site Vice President CC Administrator, Region Ill, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades*

Attachment 270037 9901270015 990120 :

PDR ADOCK 05000255 6 PDR:'

r*C (6-1998)

FORM 366 U.S. EAR REGULATORY COMMISSION APPROVED Estimated bur MB NO. 3150-0104 EXPIRES 06/30/2001 er response to comply with this mandatory information collection request: 50 hrs. Reported lessons learned are incorporated into the licensing process and fed back to industry. Forward comments I

LICENSEE EVENT REPORT (LER) regarding burden estimate to the Records Management Branch (T-6 F33l, U.S. Nuclear Regulatory Commission, Washington, DC 20555*0001, and (See reverse for required number of to the Paperwork Reduction Project (3150-0104), Office of Management and Budget, Washington, DC 20503. If an information collection does digits/characters for each block) not display a currently valid OMB control number, the NRC may not conduct or sponsor. and a person is not required to respond to, the information collection.

FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

CONSUMERS ENERGY COMPANY - PALISADES NUCLEAR PLANT 05000255 1 OF 2 TITLE 141 SAFEGUARDS TRANSFORMER TAP CHANGER FAILURE CAUSES INADVERTENT DIESEL GENERATOR START EVE \IT n~ TF l~I I CD N!llUIDCD IF; ~~~ *~ , ni >TE 171 OTHER FAr1t 1T1cC: INvnr vcn 181 FACILITY NAME DOCKET NUMBER SEQUENTIAL REVISION MONTH DAY YEAR MONTH DAY YEAR YEAR NUMBER NUMBER 05000 FACILITY NAME DOCKET NUMBER 12 22 98 98 -- 013 -- 00 01 20 99 05000 OPERATING THIS ;.;;_,*-:I IS c:1.~~  ;IT 11 DI ...... ,.l\NT TO TMI= acn1 llDC *~ENTS ni: 10 rcR §. IC:hP.r.k nn. nr ~ ..... .,, 1111 MODE (9) N 20.2201 (bl 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)

LEVEL (10) 000 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50. 73(a)(2)(iiil 73.71 20.2203(a)(2)(iil 20.2203(a)(4) x 50. 73(a)(2)(iv)

I-OTHER 20.2203(a)(2)(iii) 50.36(c)(1 l 50. 73(a)(2)(v) Specify in Abstract below 20.2203(a)(2)(iv) 50.36(c)(2) 50. 73(a)(2)(vii) or in NRC Form 366A 11ri:11.1c:FF -:: .. .;;1 ..11 FnR THIS I Fl 1121 NAME TELEPHONE NUMBER (Include Area Code!

Barbara E. Dotson (616) 764-2265 rnlUIPLETI nNc UNE FOR I ArM --- .,_ Cl\11 llDC IN rM1c: ~~-* *-: 1 1131 SYSTEM REPORTABLE REPORTABLE CAUSE COMPONENT MANUFACTURER TO. EPIX CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX x EB CNTR M175 y l'llnn1 CUCllTAI RS:PnRT ~- *un(14l MONTH DAY YEAR EXPECTED

'YES (If yes, complete EXPECTED SUBMISSION DATE). Ix I No SUBMISSION DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (161 On December 22, 1 998 at approximately 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br />, during heatup from a forced outage, a malfunction of the Safeguards Transformer automatic tap changer resulted in an undervoltage condition on 2400 volt Buses 1 C and 1 D. This undervoltage resulted in the actuation of the second level undervoltage relaying protection which caused both emergency diesel generators to start. This event is being reported in accordance with 10 CFR 50. 73(a)(2)(iv) as a condition that resulted in an automatic actuation of an engineered safety feature.

All equipment responded as expected to the event. Proper sequencing of loads onto each emergency diesel generator was verified. Subsequently, both 2400 volt buses were removed from their emergency diesel generator supply and were transferred to Startup Transformer 1-2. The cause of the event was the failure of a motor contactor in the tap chariger. The contactor was replaced, testing was completed satisfactorily and the Safeguards Transformer was returned to service.

NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 6/98 LICENSEE EVENT REPORT (LER) g TEXT CONTINUATION FACILITY NAME 11 I DOCKETt21 LEA NUMBER 61 CONSUMERS ENERGY COMPANY YEAR I SEQUENTIAL NUMBER I REVISION NUMBER PALISADES NUCLEAR PLANT 05000255 2 98 013 00 TEXT (If more space is required, use additional copies of NRC Form 366Al (17)

EVENT DESCRIPTION On December 22, 1998 at approximately 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br />, during heatup from a forced outage, a malfunction of the Safeguards Transformer automatic tap changer resulted in an undervoltage condition on 2400 volt Buses 1 C and 1D. This undervoltage resulted in the actuation of the second level undervoltage relaying protection which caused both emergency diesel generators to start and buses 1 C and 1 D to transfer to the emergency diesel generators.

All equipment responded as expected to* the event. Proper sequencing of loads onto each emergency diesel generator was verified. Subsequently, both 2400 volt buses were removed from their emergency diesel generator supply and were transferred to Startup Transformer 1-2.

A four hour non-emergency report was made to the NRC per ~ OCFR50. 72.

ANALYSIS OE THE EVENT The tap changer was found at its maximum lower position with a raise signal present. No, alarms were noted locally and all annunciator lights were functional. A review of bus voltage data on the plant computer revealed that the tap changer had been "hunting" excessively for several shifts prior to the failure. The switchyard event recorder and the plant process computer data indicated no 345 kv system disturbance which could have contributed to the problem.

Subsequent troubleshooting identified that the tap changer motor contactor failed to open properly, causing the tap changer to drive continuously to a minimum voltage position and lock-out mechanically. This contactor and the contactor which causes the tap changer to raise, were replaced.

• SAFETY SIGNIFICANCE There was no safety significance associated with this event. All equipment responded as expected.

CAUSE OE THE EVENT.

The contactor which causes the tap changer motor to move to lower positions failed.

• CORRECTIVE ACTIONS COMPLETED Both lower anq raise motor contactors were replaced. Post-maintenance testing was completed and the Safeguards Transformer was returned to service. In addition, Operations has initiated action to monitor Safeguards Transformer tap changer performance more closely.

CORRECTIVE ACTIONS REMAINING TO BE COMPLETED None.