05000220/LER-2002-002, Re Loss of One Control Rod Drive Pump Train Due to Circuit Breaker Failure

Re Loss of One Control Rod Drive Pump Train Due to Circuit Breaker Failure

ML030070698
Person / Time
Site:	Nine Mile Point
Issue date:	12/26/2002
From:	Hopkins L Constellation Energy Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
-RFPFR, NMP1L 1704 LER-02-002-00
Download: ML030070698 (5)

LER-2002-002, Re Loss of One Control Rod Drive Pump Train Due to Circuit Breaker Failure

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function
2202002002R00 - NRC Website

text

P.O. Box 63 Lycomring, New York 13093 Constelion EnegGroup nine Mile Point Nudear Station December 26, 2002 NMP1L 1704 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Nine Mile Point Unit 1 Docket No. 50-220; DPR-63 Licensee Event Report 02-002, "Loss of One Control Rod Drive Pump Train due to Circuit Breaker Failure" Gentlemen:

In accordance with 10 CFR 50.73(a)(2Xi)(B), we are submitting Licensee Event Report 02-002, "Loss of One Control Rod Drive Pump Train due to Circuit Breaker Failure".

Very truly yours, LAjIchL2 Lawrence A. Hopkins Plant General Manager LAH/IAA/jm Attachment cc:

Mr. H. J. Miller, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector 4/1

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 315040104 EXPIRES 7412004

, the NRC may not conduct or sponsor, and a peson h not required to respond to, the hiromatlon collection.

FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE ()

Nine Mile Point, Unit 1 05000220 1 OF 4

TITE (4)

Loss of One Control Rod Drive Pump Train due to Circuit Breaker Failure EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACLITES NVOLVED (8)

MO DAY YEAR YEAR SEQUENTIAL DAY YEAR FAILITY NAME DOCKET NUMBER

__IfYEAR 105000 10 17 2002 2002 -

002 -

00 12 27 2002.ITY NAUME DOCKET NUMBER j

05000 OPERATING I

THS REPORT IS SUBMITTED PURSUANT TO TIHE REQUIREMENTS OF 10 CFR f: (Check aftat apply (1)

MODE (9)

_1_

20.2201 (b) 20.2203(ax3)01) 50.73(a)(2VO(B) 50.73(a)(2)0x)(A)

POWER LEVEL (10) 100 20.2201 (d) 20.2203(aX4) 50.73(a)(2)0i0) 50.73(a)(2)(x) 20.2203(aXl) 50.36(c)(1)(1XA) 50.73(a)(2)(lv)(A) 73.71 (a)(4) 20.2203(aX)2)(

_ 50.38(c)(11)(l)(A) 50.73(a)(2)(v)(A) 73.71 (a)(5) 20.2203(asX2)I

_ 50.36(c)(2) 50.73(a)(2)(v)(B)

OThER 20 2203(aX2Il)

_50.46(aX3)00_

50.73(a)(2)(v)(C)

_Sp I h Abstract below or hI 20.2203(aX2)(Iv) 50.73(aX2)(I)(A) 50.73(a)(2)(v)(D)

NRC Form 368A 20 2203(aX2Xv)

X 0.73(aX2)(I)(B) 50.73(a)(2)v) 20.2203(X2(vl) 0.73(OX2)(1)(C) 50.73(a)(2)(vI (A)

B20.2203(aX3)Q) 50.73(aX2)(XA)

_5t.73(a)(2)(vW o)

UCENSEE CONTACT FOR THIS LER (12)

TELEPHON NUMBER (Include hea Code)

M. 0. Pearce Manager Maintenance 1

315-34-4848 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANU-REPORTABLE l

CAUSE

SYSTEM COMPONENT ANU-REPORTABLE FACIURER TO EPIX B

FACIURER TO EPiX A

EC 52 G082 YES SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED DAY YEAR SUBMISSION DATE (1 5) lYES (If yes, complete EXPECTED SUBMISSION DATE). 77 PO __

I ABSTRACT (UmIt to 1400 spaces. Le., approxrmately 15 single-spaced typewrItten ines) (16)

On October 17, 2002, at approximately 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, with Nine Mile Point Unit 1 (NMP1) at approximately 100 percent power, the #12 control rod drive (CRD) pump failed to start during performance of the quarterly srveillance. The pump was visually observed to begin rotation and then coast to a stop. Visual inspection of the pump supply circuit breaker found the breaker in the "OEN" position. A 7-day limiting condition for operation action statement was entered, as required by Technical Specification 3.1.6b. Theredundant#ll pump wasverified operable as requiredbyTS 4.1.6c. A spare breaker was identified and installed and the CRD pump successfully started. The #12 train was declared operable and the LCO action exited on October 19,2002, at approximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />. Subsequently, it was detemined that the #12 CRD pump had been inoperable from September 24, 2002, until it was declared operable on October 19, 2002. Thus, the pump was inoperable for 25 days versus 7 days allowed by TS 3.1.6b.

The cause of this event was determined to be inadequate post maintenance testing. Contributing causes included a defective ciraiit breaker over current trip device (EC trip device), and lack of compliance with applicable higher level administrative procedures.

Corrective actions included replacement of the defective circuit breaker, a thorough review of similar model circuit breakers in safety-related and non-safety related applications at NM1, and written guidance to personnel regarding post maintenance testing expectations.

NRC FORM 368 (12001)

- C FOR 36 U.S NULA EUAOYCMISO (Vrnore space iroqufre4 use addtonal copies of NRC Ferm 366A) 117)

1. Description of Event

On October 17,2002, at approximately 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br />, wiith mine Mile Point Unit 1 (NMwI) at approximately 100 percent power, the #12 control rod drive (CRD) pump failed to start during performance of the quarterly surveillance. The pump was visually observed to begin rotation and then coast to a stop. No abnormal conditions (sight, sound, odor etc.) were noticed at the pump. Tn-rush current on control room metering was observed at approximately 200 amperes, decaying to zero amperes. The green 'OFF' indicator light did not go out and the red "ON" indicator never illuminated. Visual inspection found the circuit breaker in the "OPEN" position. The surveillance was placed on hold. The control room was notified and a 7-day limiting condition for operation (LCO) action statement, as required by Technical Specification (TS) 3.1.6b, was entered. The redundant #11 CRD pump was verified operable as required by TS 4.1.6c. Additionally, an Action Request was generated to perform troubleshooting of this event.

Troubleshooting confirmed that the circuit breaker (General Electric 600 Volt Model AK-2A-25) had attempted to shut and immediately tripped open. Review of the breaker's maintenance history revealed that its routine preventive maintenance had been completed on September 24, 2002. During that preventive maintenance, the breaker's original phase "A" instantaneous over current (type EC-2A) trip device had faied its "as-found" test and was replaced. The "as-left" EC trip device test was satisfactory. It is significant to note that post maintenance testing was conducted with the breaker racked out to the "Test' position rather than being in the "Racked In" position. Testing the breaker in this manner verifies functionality of the breaker's control circuit but does not pass load current through the instantaneous over current trip device, and therefore does not test the breaker's ability to perform its design function to start the pump. This is also contrary to the higher level procedure requiring that the applicable surveillance, including starting the pump in this particular case, be performed after any breaker maintenance.

During troubleshooting for this event, the "as-found" and "as-left" tests were successfully performed on the breaker's EC trip devices with no failures noted. However, during additional EC trip device testing, the phase "A" EC trip device trip set point was found to have drifted slightlybelow the lower tolerance limit. However, the low trip occurred only once out of five times during the troubleshooting. The breaker was quarantined for analysis. A spare breaker was then identified and installed after successfil completion of the preventive maintenance procedure. The CRD pump was successfully started three times. The redundant #12 CRD train was declared operable and the LCO action exited on October 19, 2002 at approximately 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />.

On November 4, 2002, it was determined that this event is reportable. This determination was based on an assessment that the #12 CRD pump had been inoperable from the time it was taken out of service for maintenance on September 24, 2002, until it was successfully tested and declared operable on October 19, 2002 (total of 25 days). This period of inoperability exceeded the 7-day LCO action statement in TS 3.1.6b.

II. Cause of Event

The cause of this event was determined to be inadequate post maintenance testing Contributing causes included a defective circuit breaker over current trip device (EC trip device) where the set point drifted slightly below the lower tolerance limit, and lack of compliance with applicable higher level administrative procedures.

IIl. Analysis of Event This event is reportable in accordance with 10CFRS0.73(aX2)(i) (B), "Any operation or condition which was prohibited by the plant's Technical Specifications...."

NRC FORM 388A (1.2001)

(if mor space i required, use additional copies of NRC Fnrm 366A) (1 7) 111. Analysis of Event (Cont'd.)

The # 11 and #12 CR1D pumps are part of the control rod drive hydraulic system. This system is designed to change the control rod positions within the reactor core in response to manual control signals, charge the scam accumulators, and provide high pressure makeup to the reactor vessel for a "Twenty-five gallons per minute total leakage...," as specified in TS 3.2.5, "Reactor Coolant Systemt Leakage." The system can also provide core cooling in the event of a small line break (up to 0.003 square feet). Normal system operation is with one pump running and the other pump on standby. Electrical power for this system is normally available from the reserve transformer. Automatic initiation is provided to start each pump from its respective diesel generator in case offsite power is lost.

Each CRD pump can supply 50 gpm within 60 seconds of receipt of an automatic initiation signal. The 60-second delay in pump starting assures that automatic prssure blowdown is not actuated for the TS specified leakage rate of 25 gpm.

TS 3.1.6, "Control Rod Drive Pump Coolant Injection," requires the coolant injection system to be operable whenever irradiated fuel is in the reactor vessel and the reactor coolant tempeature is greater than 2120iF with one exception: if a redundant component (such as #11 or #12 CRD pump) becomes inoperable, the control rod drive pump coolant injection system shall be considered operable provided the inoperable component is returned to an operable condition within 7 days and the operability of the redundant component is verified "immediately and daily thereafter."

Currently, no credit is taken for the CRD high pressure coolant injection function to mitigate the consequences of a Loss of Coolant Accident (LOCA), as evaluated in the 10CFR50 Appendix K LOCA analysis. A probabilistic risk assessment evaluation concluded that the increase in core damage frequency due to this event is small (2. 57E-7/year) and as such this event has low safety significance.

Based on the above, the event did not pose a thrat to the health and safety of plant personnel or the public.

IV. Corrective Actions

1.

Maintenance replaced the defective circuit breaker with a suitable spare breaker.

2.

Maintenance conducted a thorough review of all safety-related and non-safety related 600 Volts AC GE Model AK circuit breakers installed at NMPl. Three circuit breakers were identified as needing further testing and the testing was successfully completed. No other GE Model AK circuit breakers at NMP1 are impacted by this event

3.

The Maintenance and Operations Managers issued written guidance to Operations, Work Control, Planning, and Maintenance organizations clarifying management expectations regarding conduct and control of post maintenance testing on circuit breakers to ensure compliance with the higher level procedure.

N.C (ifmore space Is required, use eddfitonsa copies of NRC Form 366A) (17)

V. Additional Information

A. Failed components:

Circuit breaker General Electric 600 Volt Model AK-2A-25

B. Previous similar events

During an event in 1999 (refueling outage number 15), shutdown cooling pump #13 tripped immediately on a start attempt The other two shutdown cooling pumps were available and one was already runming. The breaker (GE Model AK) EC trip devices were found to be tripping slightly low. Upon review, the set point specifications were found to be lower than design guidance. The calculation was revised and the set point specifications were changed to conform to design guidance. The trip devices were then reset accordingly.

C. Identification of components referred to in this Licensee Event Report EEmpE8nents IEEE 805 System IEEE 803AFuncton Control Rod Drive System AA N/A Reactor Core System AC N/A Low Voltage Power System EC NIA Emergency Diesel System EK N/A Reactor Recirculation System AD N/A Pump AA P

Circuit Breaker EC, AA 52 Fuel Rod AC ROD Control Rod AA ROD Trip Device EC NIA Indicator (Light)

EC IL Accumulator AA ACC