05000353/LER-2008-002, Re Automatic Actuation of the Reactor Protection System at Power

Re Automatic Actuation of the Reactor Protection System at Power

ML080910061
Person / Time
Site:	Limerick
Issue date:	03/31/2008
From:	Mudrick C Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 08-002-00
Download: ML080910061 (6)

LER-2008-002, Re Automatic Actuation of the Reactor Protection System at Power

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 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)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 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 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x)
3532008002R00 - NRC Website

text

10CFR50.73 March 31, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 2 Facility Operating License No. NPF-85 NRC Docket No. 50-353

Subject:

LER 2008-002-00, Automatic Actuation Of The Reactor Protection System At Power This Licensee Event Report (LER) addresses an event that resulted in an automatic actuation of the reactor protection system (RPS) at power. A phase-to-ground fault occurred at the 2A Main Transformer low voltage (22 kV) bushing connection to the Iso-Phase Bus. The Main Generator neutral overvoltage relay actuated and tripped the generator protection lockout relays, which resulted in a Main Turbine trip.

This LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(iv)(A).

There are no commitments contained in this letter.

If you have any questions or require additional information, please do not hesitate to contact us.

Sincerely, Original signed by Christopher H. Mudrick Vice President - Limerick Generating Station Exelon Generation Company, LLC cc: S. J. Collins, Administrator Region I, USNRC E. M. DiPaolo, USNRC Senior Resident Inspector, LGS

NRC FORM 366 (9-2007)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

LICENSEE EVENT REPORT (LER)

(See reverse for required number of digits/characters for each block)

APPROVED BY OMB NO. 3150-0104 EXPIRES 08/31/2010

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

1. FACILITY NAME Limerick Generating Station, Unit 2

2. DOCKET NUMBER 05000353

3. PAGE 1 of 5

4. TITLE:

Automatic Actuation Of The Reactor Protection System At Power

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

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

MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 02 01 2008 2008 - 002 - 00 03 31 2008 FACILITY NAME DOCKET NUMBER 05000

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1

10. POWER LEVEL 100 20.2201(b) 20.2201(d) 20.2203(a)(1) 20.2203(a)(2)(i) 20.2203(a)(2)(ii) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(i) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(i)(C) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(vii) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5)

OTHER Specify in Abstract below or in (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)

Previous Similar Occurrences There were no previous similar occurrences of scrams caused by Iso-Phase bus ground faults. However, a scram due to overheating of the Doble links of a Main Transformer high voltage bushing was reported in LER 1-00-002. The corrective actions for the previous event were effectively implemented. However, during the transition of Main Transformer maintenance from EED to the station Maintenance organization, they were not subsequently transferred from EED procedures into station site procedures due to less than adequate change management.

Component data:

Component description:

2A Main Transformer Component number:

2A-X101 Manufacturer:

M175 McGraw Edison Co Model number:

CC-464368 DWG Serial number:

C-07005-5-3

References:

M-035-003, X101 Oil Cooled Transformers Cleaning, Examination, and Testing M-200-005, Non-safety Related Oil Cooled Transformers Clean and Examine