05000352/LER-2005-005, Missed Surveillance Resulted in a Condition Prohibited by Technical Specifications

Missed Surveillance Resulted in a Condition Prohibited by Technical Specifications

ML053640423
Person / Time
Site:	Limerick
Issue date:	12/30/2005
From:	Degregorio R Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 05-005-00
Download: ML053640423 (6)

LER-2005-005, Missed Surveillance Resulted in a Condition Prohibited by Technical Specifications

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
3522005005R00 - NRC Website

text

10CFR50.73 December 30, 2005 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 1 and Unit 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353

Subject:

LER 1-05-005, Missed Surveillance Resulted In A Condition Prohibited By Technical Specifications This Licensee Event Report (LER) addresses a condition prohibited by Technical Specifications.

An offsite circuit calculation credited a ten second time delay on 101 and 201 safeguard transformer tap changers in the automatic mode to maintain operability of the offsite circuits.

The associated offsite circuit should have been considered inoperable when the automatic voltage control (AVC) was operating in manual mode under certain configurations of the safeguard buses. A subsequent review of the three year reporting period identified occasions when the station operated in these configurations and did not take the required Technical Specification actions.

Report Number:

1-05-005 Revision:

00 Event Date:

October 5, 1992 Discovered Date:

November 3, 2005 Report Date:

December 30, 2005 This LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(i)(B).

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

Sincerely, Original signed by Ron J. DeGregorio Vice President - Limerick Exelon Generation Company, LLC cc: S. J. Collins, Administrator Region I, USNRC S. L. Hansell, USNRC Senior Resident Inspector, LGS

SUMMARY OF EXELON NUCLEAR COMMITMENTS LS-AA-117-1003 Rev.2 The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)

Commitment #1 Committed date (or "outage"):

3/31/06 A modification will be implemented to change the AVC time delays on 10, 20, 101 and 201 transformers. As a result the offsite circuits will remain operable when 101 and 201 transformer AVCs are placed in manual mode.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-2004)

LICENSEE EVENT REPORT (LER)

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

APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007

, 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 1

2. DOCKET NUMBER 05000352

3. PAGE 1 OF 4

4. TITLE Missed Surveillance Resulted In A Condition Prohibited By Technical Specifications

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 Limerick Unit 2 DOCKET NUMBER 05000353 10 05 1992 2005 - 005 -

0 12 30 2005 FACILITY NAME DOCKET NUMBER 05000

9. OPERATING MODE 1

10. POWER LEVEL 100

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)

OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 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)

As a result of this event, a modification will be implemented to change the 10 and 20 transformer AVC time delay to 10 seconds. The modification also will change the 101 transformer AVC time delay from 10 seconds to 17 seconds, and 201 transformer AVC time delay from 10 seconds to 20 seconds. This modification will allow the AVC for the safeguard transformer on each OSC to be placed in manual mode without requiring the OSC to be declared inoperable.

The AVC on both station auxiliary transformers (10 and 20) must be maintained in automatic mode to support OSC operability. Otherwise, engineering analysis of the specific conditions will be required to determine OSC operability.

Cause of the Event

The event was caused by a failure to properly implement the requirement to maintain the 101 and 201 safeguard transformers AVC in the automatic mode following a modification that changed the AVC time delays from 30 seconds to 10 seconds.

Corrective Action Completed An interim corrective action was implemented which revised procedures to ensure that the OSC is declared inoperable when 101 or 201 transformer AVC is placed in manual mode.

Corrective Actions Planned A modification will be implemented to change the AVC time delays on 10, 20, 101 and 201 transformers. As a result the OSCs will remain operable when 101 and 201 transformer AVCs are placed in manual mode. This action will be complete by March 31, 2006.

Previous Similar Occurrences There were no previous events where OSCs were rendered inoperable as a result of inadequate implementation of a modification.