ML18065A874

LER 96-010-00:on 960717,high Pressure Safety Injection Pump Tripped While Filling Safety Injection Tank.Caused by Faulty 150/151Y-207 Time Overcurrent Relay.All Similar Relays in Time Overcurrent Application Have Been Inspected

ML18065A874
Person / Time
Site:	Palisades
Issue date:	08/16/1996
From:	MATHEWS C M CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Shared Package
ML18065A873	List: ML18065A872 ML18065A874
References
LER-96-010, LER-96-10, NUDOCS 9608230145
Download: ML18065A874 (3)

Text

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3160-0104 (4195) . -EXPIRES 4130/98 ESTIMATED IUIOEN PER RESPONSE TO COMPLY WllH THIS llAHDATORY INFORMATION OOUECTlON REQUEST: 50.0 HRS. REPORTED LESSONS LEARNED ARE INCORPORATED LICENSEE EVENT REPORT (LER) INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY.

FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS llAN.\GEMEHT BRANCH (T-8 F33), U.S. NJClEAR REOULATORY COMMISSION, WASHINGTON, DC 21)5511. (See reverse for required number of digits/characters for each block) OOOt, NIO TO THE PAPERV<<>RK REDUC'TION PROJECT (3t!IO-Ot0<, OFFICE OF llAN.\GEMEHT NIO BUDGET, WASHIHGTON, DC 20503 FACILITY NAME (1) DOCKET NUMBER (2) Page (3) PALISADES NUCLEAR PLANT 05000255 1of3 TITLE (4) LICENSEE EVENT REPORT 96-010-TRIP OF HIGH PRESSURE SAFETY INJECTION PUMP WHILE FILLING SAFETY INJECTION TANK EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8) MONTH DAY YEAR YEAR I SEQUENTIAL REVISION MONTH DAY YEAR FACILITY NAME DOCKET NUMBER NUMBER NUMBER 05000 07 17 96 96 010 00 08 16 96 FACILITY NAME DOCKET NUMBER --05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check one or more) (11) MODE (9) N 20.2201(b) 20.2203(a)(2)(v) x 50.73(a)(2)(1)

50. 73(a)(2)(iii)

POWER 20.2203(a)(1) 20.2203(a)(3)(1) 50.73(a)(2)(ii) 50.73(a)(2)(x)

EL (10) 99.6 20.2203(a)(2)(1) 20.2203(a)(3)(ii)

50. 73(a)(2)(iii) 73.71 1 1:1:: Ifill 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv)

OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)

Specify in Abstract below or 20.2203(a)(2)(iv) 50.36(c)(2)

50. 73( al (2)(vii) in NRC Fonn 366A LICENSEE CONTACT FOR THIS LE'R (12) NAME TELEPHONE NUMBER (Include Area Code) Clayton M. Mathews (616) 764-2035 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS x ED RLY GOBO Yes SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR I YES x I NO EXPECTED If yes COMPLETE EXPECTED COMPLETION DATE SUBMISSION DATE (15) ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16) On July 17, 1996, at 2114 hours0.0245 days <br />0.587 hours <br />0.0035 weeks <br />8.04377e-4 months <br />, with the reactor at 99.6% power, the Safety Injection Tanks (SIT) were being sampled to verify boron concentration.

While filling SIT T-82C with High Pressure Safety Injection (HPSI) Pump P-66A, P-66Atripped.

Since T-82C was inoperable due to low pressure during the sampling evolution, Technical Specification (TS) 3.0.3 was immediately entered. Two minutes later, TS 3.0.3 was exited when nitrogen overpressure was restored.

The 24-hour Limiting Condition of Operation (LCO) of TS 3.3.2.c was then entered for P-66A. The trip of P-66A was found to be due to its Y-phase time-overcurrent relay actuation.

Troubleshooting revealed that P-66A tripped due to its relay not properly resetting after each successive start. The start of P-66A for the fill of T-82C was sufficient to reach the overcurrent trip setpoint.

Following checking and cleaning the P-66A motor, and checking the calibration of and exercising the relay, P-66A was test started three times. Proper relay reset was verified each time. P-66A was then declared operable, but degraded.

On July 18, 1996, the LCO was exited. The relay was replaced on July 19, 1996, correcting the degraded condition of the breaker. 9608230145 ADOCK PDR NRC FORM 366a 4/95 FACILITY NAME l1l PALISADES NUCLEAR PLANT U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET12l LER NUMBER 6) 05000255 YEAR I SEQUENTIAL I REVISION NUMBER NUMBER 96 010 00 PAGE13l 20F3 TEXT (If niore space is required, use additional copies of NRC Form 366A) (17) EVENT DESCRIPTION On July 17, 1996, at 2114 hours0.0245 days <br />0.587 hours <br />0.0035 weeks <br />8.04377e-4 months <br />, with the reactor at 99.6% power, Safety Injection Tanks (SIT) T -82 A, B, C and D were being sampled to verify boron coricentration, in accordance with Technical Specification Table 4.2.1, Item 5. While filling SIT T-82C with High Pressure Safety Injection (HPSI) Pump P-66A in accordance with System Operating Procedure SOP 3, P-66A tripped approximately two seconds after having been started. Since T-82C was coincidentally inoperable due to low pressure as a result of the sampling evolution, Technical Specification (TS) 3.0.3 was immediately entered. TS 3.0.3 was exited approximately two minutes later when operators restored nitrogen overpressure to T-82C. The Limiting Condition of Operation (LCO) of Technical Specification 3.3.2.c was then entered for P-66A. Observation of the pump breaker 152-207 relays indicated that the trip of P-66A was due to Y-phase time-overcurrent relay actuation (ED;RL Y). Troubleshooting revealed that P-66A tripped due to relay 150/151 Y-207 not properly resetting after each successive start of P-66A for SIT fill; i.e., the induction disc portion of the relay was not returning to its initial position.

The third start of P-66A, for the fill of T-82C, was apparently sufficient for the induction disc to travel to its overcurrent trip setpoint.

Thus, Y-phase time-overcurrent, in conjunction with the Y-phase high drop-out relay (which was picked up as a result of the P-66A start), then tripped breaker 152-207. A replacement GE overcurrent relay was not immediately available.

Following checking and cleaning the P-66A motor, and checking the calibration of and exercising relay 150/151Y-207, P-66A was successfully test started three times. Proper relay reset was verified each time. P-66A was then declared operable, but degraded due to the suspect condition of relay 150/151 Y-207). On July 18, 1996, at 1102 hours0.0128 days <br />0.306 hours <br />0.00182 weeks <br />4.19311e-4 months <br />, the LCO of TS 3.3.2.c was exited. Relay 150/151 Y-207 was replaced on July 19, 1996, correcting the degraded condition of breaker 152-207. ROOT CAUSE The apparent cause of the event was a faulty 150/151Y-207 time-overcurrent relay. Some type of minor mechanical interference (dust, grease, etc.) preventerl its induction reset mechanism from returning to its initial position, resulting, ultimately, in the re1ay reaching its overcurrent trip point during the series of P-66A starts to refill the SITs. No definitive evidence of this was found during troubleshooting, with the exception that the faulty relay immediately reset when the breaker cubicle door was opened for troubleshooting.

The one-time failure of relay 150/151 Y-207 is considered random.

NRC FORM 366a U.S. NUCLEAR REGULATORY COMMISSION 4195 -FACILITY NAME 11\ PALISADES NUCLEAR PLANT LICENSEE EVENT REPORT (LER) TEXT CONTINUATION DOCKET121 05000255 LER NUMBER 6\ YEAR I SEQUENTIAL NUMBER 96 010 -TEXT (If more space is required, use additional copies of NRC Form 366A) (17) SAFETY IMPLICATIONS REVISION NUMBER 00 PAGE 131 30F3 When P-66A tripped, it rendered one HPSI train inoperable and interrupted the refill of T-82C. Aithough T-82C was inoperable due to its pressure being outside of Technical Specifications limits during sampling, it is likely that its safety function could still have been performed.

Even if it could not have performed its safety function, however, the Loss of Coolant Accident (LOCA) analysis assumes that only 3 of 4 SITs are available to inject their contents into the Primary Coolant System(PCS).

Since T-82 A, 8, and D were operable, the loss of T-82C would not have had any significant effect. Since P-66A is the only pump allowed for filling SITs with PCS pressure greater than 1500 psia per SOP 3, no procedural method to restore the T-82C level was available.

In this case, although T-82C level was low, it was still within the required Technical Specifications limits. Operability of T-82C was quickly restored by raising nitrogen pressure.

If level had been outside the Technical Specification limits, however, the unavailability of P-66A would have delayed restoration significantly.

The use of P-668 to fill SITs via the Train 1 HPSI header under the same PCS conditions as permitted for P-66A appears to be a technically adequate alternative which should be incorporated into SOP 3. CORRECTIVE ACTION CORRECTIVE ACTION TAKEN AND RESULTS ACHIEVED All similar relays in a time-overcurrent application were inspected for potentially degraded conditions.

No other potential-problem relays were found. CORRECTIVE ACTION TO PREVENT RECURRENCE

.1. Review the stock balance of spare motor protection relays for all safety-related motors. Procure necessary spare relays as considered appropriate by System Engineering.

2. Revise Standard Operating Procedure (SOP) 3 to permit the use of High Pressure Safety Injection (HPSI) Pump P-668 to fill Safety Injection Tanks at full Primary Coolant System pressure, if justified by engineering analysis.