05000251/LER-2013-002, Reactor Trip Due to Loss of Offsite Power Resulting from Generator Testing

Reactor Trip Due to Loss of Offsite Power Resulting from Generator Testing

ML13183A066
Person / Time
Site:	Turkey Point
Issue date:	06/18/2013
From:	Kiley M Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2013-194 LER 13-002-00
Download: ML13183A066 (5)

LER-2013-002, Reactor Trip Due to Loss of Offsite Power Resulting from Generator Testing

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2512013002R00 - NRC Website

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L-2013-194 10 CFR § 50.73 June 12, 2013 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:

Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 2013-002-00 Reactor Trip Due to Loss of Offsite Power Resulting From Generator Testing The attached Licensee Event Report 05000251/2013-002-00 is submitted in accordance with 10 CFR 50.73(a)(2)(iv)(A) due to safety system actuations and 10 CFR 50.73(a)(2)(v)(D) because primary power was lost to accident mitigation systems for approximately 30 minutes.

If there are any questions, please call Mr. Robert J. Tomonto at 305-246-7327.

Very truly yours, Michael Kiley Vice President Turkey Point Nuclear Plant Attachment cc:

Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Florida City, FL 33035

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Turkey Point Unit 4 05000251 7 1 of 4

4. TITLE Reactor Trip Due to Loss of Offsite Power Resulting From Generator Testing

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

[

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR IFACILITY NAME DOCKET NUMBER NUMBER NO.

_ _NH I

_YEA I

I FACILITY NAME DOCKET NUMBER 4

19 2013 2013-002 -00 6

18 2013

9. OPERATING MODE II. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) 0l 20.2201(b) 0l 20.2203(a)(3)(i)

[I 50.73(a)(2)(i)(C)

El 50.73(a)(2)(vii) 29 [1 20.2201(d)

El 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A) 0l 50.73(a)(2)(viii)(A)

El 20.2203(a)(I) 0l 20.2203(a)(4)

[I 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(viii)(B)

El 20.2203(a)(2)(i) 0l 50.36(c)(1)(i)(A) 0l 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL El 20.2203(a)(2)(ii) 0l 50.36(c)(1)(ii)(A)

[D 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

El 20.2203(a)(2)(iii) 0l 50.36(c)(2)

[I 50.73(a)(2)(v)(A)

[I 73.71(a)(4)

El 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii)0 El 50.73(a)(2)(v)(B)

Cl 73.71(a)(5) 1E 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

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

El OTHER El 20.2203(a)(2)(vi) 0l 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)

Specify in Abstract below or in than normal 100% power operations and does not describe the transition from outage to on-line risk management.

ANALYSIS OF THE EVENT

The 3 rd harmonic relay power ascension test was being performed after an EPU outage. The purpose of the test is to obtain voltage data for the Unit 4 generator at various power levels during power ascension. The data is used to determine the 3 rd harmonic relay settings to be implemented in the multifunctional generator protection relays [EL, RLY]. As part of the testing main generator exciter [EL, EXC] voltage was lowered to provide a MVAR range for data collection.

After subsequent review of voltages and the sequence of events report, it was identified that the voltage at the 4D LC fell below the nominal 434V +/- 3 for greater than 60 seconds actuating the degraded voltage relays [ED, RLY, 27]. The relays initiated 4B sequencer bus load shedding. Shortly thereafter, 4A LC voltage fell below the nominal 430V + 3 for greater than 60 seconds actuating the degraded voltage relays. The relays initiated 4A sequencer bus load shedding.

In response to the identified conditions the degraded voltage relays and sequencers performed their intended function. The vital buses were load shed and then repowered by the EDGs as designed.

ANALYSIS OF SAFETY SIGNIFICANCE Plant response to the LOOP was as expected. The vital bus loads were shed, and the EDGs started and repowered the buses. Offsite power was restored to the vital buses in approximately 30 minutes, but continued to power the 4C non-essential buses the whole time. Core cooling was maintained via natural circulation until RCPs were restarted with the first RCP starting approximately 67 minutes after the LOOP.

The AFW System maintained water level in the steam generators until a Standby Steam Generator Feed Pump was started approximately 55 minutes after the LOOP. The AFW System was secured and restored to standby service approximately 102 minutes after the LOOP.

Given the successful start of the EDGs and AFW, and restoration of offsite power to vital buses in approximately 30 minutes, the safety significance of this event is considered to be very low.

CORRECTIVE ACTIONS

Corrective actions are documented in AR 1867690 and include the following:

1. Eliminate the use of test instructions as an acceptable way to control plant operation.

2. Provide additional risk recognition guidance in the Work Activity Risk Management procedure to include additional checks and balances for low risk activities, address evolutions for the electrical

generator other than at normal 100% power operation, and identify the process to transition from outage to on-line risk management.

3. Include criteria in the Operations pre-job brief checklist that would question evolutions that would change electrical generator operation.

4. Develop and implement a comprehensive program on risk recognition and management.

5. Add risk recognition to supplemental worker training and qualification consistent with the guidance in the Work Activity Risk Management procedure.

6. Include the operating limits for the switchyard, 4kV and LC voltages in the general operating procedure precautions and limitations.

FAILED COMPONENTS IDENTIFIED: None

PREVIOUS SIMILAR EVENTS

None

ADDITIONAL INFORMATION

EIIS codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].