05000443/LER-2006-006, Regarding Plant Shutdown Due to Inoperable Emergency Diesel Generators
| ML063040320 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 10/27/2006 |
| From: | St.Pierre G Florida Power & Light Energy Seabrook |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SBK-L-06207 LER 06-006-00 | |
| Download: ML063040320 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(iv)(A), System Actuation 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)(v), Loss of Safety Function |
| 4432006006R00 - NRC Website | |
text
0FPL Energy Seabrook Station FPL Energy Seabrook Station P.O. Box 300 Seabrook, NH 03874 (603) 773-7000 October 27, 2006 Docket No. 50-443 SBK-L-06207 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Seabrook Station Licensee Event Report (LER) 2006-006-00 Plant Shutdown Due to Inoperable Diesel Generators Enclosed is Licensee Event Report (LER) 2006-006-00. This LER reports an event that occurred at Seabrook Station on August 31, 2006. This event is being reported pursuant to the requirements of IOCFR50.73(a)(2)(i)(B).
Should you require further information regarding this matter, please contact Mr. James M.
Peschel, Regulatory Programs Manager, at (603) 773-7194.
Very truly yours, FPL Energy Seabrook, LLC Ge Pierre Site Vice Presid(
cc:
S. J. Collins, NRC Region I Administrator G. E. Miller, NRC Project Manager, Project Directorate 1-2 G. T. Dentel, NRC Senior Resident Inspector an FPL Group company
ENCLOSURE TO SBK-L-06207
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may igtscharacters for each block)iormtinot conduct or sponsor, and a person is not required to respond to, the dJigischrctr fo ahboknformation collection.
- 3. PAGE Seabrook Station 05000443 1 OF 3
- 4. TITLE Plant Shutdown Due to Inoperable Emergency Diesel Generators
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR N/A 05000 NUMBER NO.05 0
FACILITY NAME DOCKET NUMBER 08 31 2006 2006
- - 006 00 10 27 2006 N/A 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[I 50.73(a)(2)(vii) 1E 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[3 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
El 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)
[1 50.36(c)(1)(ii)(A)
[I 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
E] 50.73(a)(2)(v)(A)
[1 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
M 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below
___________________or in (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
Both EDGs were inoperable for approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, from 1409 on August 31 to 1359 on September 1, 2006. This event met the reporting criteria of 1 OCFR50.72(b)(2)(i) and 50.73(a)(2)(i)(A) for initiation and completion of a plant shutdown required by the TS. This event is of regulatory significance because the condition was sufficiently serious to warrant a plant shutdown. Nonetheless, no systems actuations or consequences resulted from the event, and this occurrence had no adverse impact on the plant or on the health and safety of the public. No inoperable structures, systems, or components other than the EDGs contributed to the event.
While inoperable for planned maintenance on August 31, 2006 the train-A EDG experienced a voltage regulator diode failure light indication during a test run. However, the EDG satisfied the technical specification requirements for voltage and frequency. The generator voltage attained its nominal value in less than ten seconds following starting of the engine, and voltage was maintained during operation of the EDG. EDG-A was capable of carrying full load during and after the time that the diode failure light was on. Data obtained during the test run showed that one SCR was providing the required power contribution to the generator field, one SCR was providing a partial contribution, and one SCR was not providing any contribution to the generator field. The difference between the SCR power contributions was the reason the diode failure light was lit. Based on test data and vendor information, only one SCR is required to maintain generator voltage at full load. Therefore, EDG-A was functional and capable of carrying full load and fulfilling the safety function of the on-site emergency power system.
During this event, the Supplemental Emergency Power System (SEPS) was available and capable of carrying its design bases emergency loads. Additionally, all three offsite lines and associated on-site transformers were available to power the emergency buses. Based on the functional capability of EDG-A, the PRA risk assessment for the event determined that the incremental core damage probability (ICDP) was 6.88E-07.
IV. Corrective Actions
The corrective actions for the failures of the EDG voltage regulators will be determined upon completion of the root cause evaluation of this event. The immediate corrective actions consisted of replacing numerous components in the voltage regulator systems on both EDGs. As an interim measure, until the start of OR1 1, the station is performed surveillance testing of each EDG on a two-week interval. On September 27, 2006 EGD-A experienced an additional diode failure alarm.
The subsequent troubleshooting determined that the K1 contactor was defective with one phase not making ideal contact. The contactor was replaced.
Similar Events
The emergency diesel generators have previously experienced voltage regulator failures; however, none of these events resulted in a plant shutdown or reportable event.