05000353/LER-2005-002, Regarding Unit 2 High Pressure Coolant Injection (HPCI) Inoperable
| ML051460339 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/26/2005 |
| From: | Degregorio R Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 05-002-00 | |
| Download: ML051460339 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(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)(i)(B), Prohibited by Technical Specifications |
| 3532005002R00 - NRC Website | |
text
10CFR50.73 May 26, 2005 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 2-05-002, Unit 2 High Pressure Coolant Injection (HPCI) Inoperable This Licensee Event Report (LER) addresses a Limerick Unit 2 condition that could have prevented the fulfillment of a safety function. The HPCI system was rendered inoperable due to a degraded control power fuse clip for the outboard suppression pool suction motor operated valve (MOV).
Report Number:
2-05-002 Revision:
00 Event Date:
March 28, 2005 Discovered Date:
March 28, 2005 Report Date:
May 26, 2005 This LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(v)(D).
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 Attachment 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. These actions are described to the NRC for the NRCs information and are not intended as regulatory commitments.
Commitment #1 Committed Date (or Outage):
The procedure for periodic maintenance of Westinghouse 250 VDC magnetic starters will be revised to include a closer examination of the fuse block rivets by July 29, 2005.
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 2
- 2. DOCKET NUMBER 05000353
- 3. PAGE 1 OF 4
- 4. TITLE High Pressure Coolant Injection System Inoperable due to a Degraded Control Power Fuse Clip
- 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 03 28 2005 2005 - 002 - 0 05 26 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 NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME John G. Hunter III, Acting Manager-Regulatory Assurance TELEPHONE NUMBER (Include Area Code) 610 718-3400 CAUSE SYSTEM COMPONENT MANU-FACTURER REPORTABLE TO EPIX
CAUSE
SYSTEM COMPONENT MANU-FACTURER REPORTABLE TO EPIX B
BJ 20 B250 Y
B BJ FUB W120 N
MONTH DAY YEAR
- 14. SUPPLEMENTAL REPORT EXPECTED YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO
- 15. EXPECTED SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
The Unit 2 High Pressure Coolant Injection System (HPCI) was declared inoperable due to loss of the suction automatic transfer function when the HPCI outboard suppression pool suction motor operated valve (MOV) lost control power due to a manufacturing defect in the control power fuse clip for the MOV. The fuse clip was replaced and the HPCI MOV was satisfactorily tested. The HPCI system was then declared operable. The procedure for periodic maintenance of Westinghouse 250 VDC magnetic starters will be revised to include a closer examination of the fuse block rivets.
NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPER (1-2001)
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL NUMBER REVISION NUMBER Limerick Generating Station, Unit 2 05000353 2005 002 00 2
OF 4
NARRATIV (If more space is required, use additional copies of NRC Form 366A) (17)
E Unit Conditions Prior to the Event Unit 2 was in Operational Condition (OPCON) 1 (Power Operation) at approximately 100%
power. There were no structures, systems or components out of service that contributed to this event.
Description of the Event On Monday March 28, 2005, at 17:38 hours, while Unit 2 was operating at approximately 100%
power, the Main Control Room position indication on the High Pressure Coolant Injection (HPCI) [EIIS: BJ] system outboard suppression pool suction motor operated valve (MOV) HV-055-2F041 was lost and the HPCI out-of-service alarm annunciated. HPCI was declared inoperable and Technical Specification 3.5.1 Action c.1 was entered, which requires system restoration to operable status within 14 days.
An investigation determined that the condition was caused by a loose control power fuse clip [EIIS: FUB] located on the 250 VDC circuit breaker, which resulted in loss of control power to the MOV. The degraded fuse clip was replaced and the MOV was successfully stroked. The Unit 2 HPCI system was restored to operability at 21:30 hours.
The Reactor Core Isolation Cooling (RCIC) [EIIS: BN] system remained operable during the entire period from when the loss of control power to the HPCI MOV occurred until the HPCI system was restored to operability at 21:30 hours.
This event involved the potential loss of safety function of the Unit 2 HPCI system for 3.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> from March 28, 2005 17:38 to March 28, 2005 21:30. The 8-hour ENS notification required by 10CFR50.72(b)(3)(v)(D), was completed on March 28, 2005 at 23:56 EDT hours (Event#
41540).
This event involved a condition that could have prevented the fulfillment of the safety function of the HPCI system to mitigate the consequences of an accident; therefore, this LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(v)(D).
Analysis of the Event
There were no actual safety consequences associated with this event. The potential safety consequences of this event were also minimal. HPCI suction was aligned to the condensate storage tank (CST) at the time of the failure; therefore, the initial system response to a loss of coolant accident was unaffected. The HPCI pump suction would not have automatically transferred from the CST to the suppression pool on a CST low level condition or a suppression pool high level condition. The CST has the capacity to provide full flow HPCI injection for approximately 15 minutes before needing to transfer to suction from the suppression pool. The HPCI response to a station black out (SBO) accident was potentially adversely affected since the follow-up operator actions require transferring the HPCI suction to the suppression pool. The reactor core isolation cooling (RCIC) system was operable during the period when HPCI was adversely affected by the fuse clip failure. (1-2001)
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL NUMBER REVISION NUMBER Limerick Generating Station, Unit 2 05000353 2005 002 00 3
OF 4
NARRATIV (If more space is required, use additional copies of NRC Form 366A) (17)
E The terminal block, fuse clip, and rivets are part of a single assembly supplied by Westinghouse with Eaton Electric as the dedicated supplier (part number TBAF3).
These terminal blocks/ fuse clips are utilized in safeguard DC Motor Control Center applications for both the Limerick Unit 1 and Unit 2 HPCI and RCIC.
The laboratory analysis of the failure of the fuse clip determined that the loss of continuity was due to a loose rivet on the fuse clip that was not properly swagged during manufacturing.
The preventive maintenance (PM) procedures in place include inspection of the terminal block and fuse clips for loose connection, cracks, and other visible damage. The terminal block is not removed during the PM inspection. It was determined that the PM procedure should be enhanced to include inspection of the fuse block rivets for complete roll and tightness.
Cause of the Event
The cause of the event was a loss of control power to the HPCI pump suction outboard motor operated valve as a result of a manufacturing defect in the control power fuse clip.
Corrective Action Completed The degraded fuse clip was replaced. Storeroom inventories of replacement parts for the fuse clips were visually inspected and no deficiencies were identified.
Corrective Action Planned The procedure for periodic maintenance of Westinghouse 250 VDC magnetic starters will be revised to include a closer examination of the fuse block rivets by July 29, 2005.
Previous Similar Occurrences There were no previous occurrences of a loss of MOV control power rendering HPCI inoperable. (1-2001)
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL NUMBER REVISION NUMBER Limerick Generating Station, Unit 2 05000353 2005 002 00 4
OF 4
NARRATIV (If more space is required, use additional copies of NRC Form 366A) (17)
E Component data:
Cause
B (Design, Manufacturing, Construction/Installation)
System:
BJ (High Pressure Coolant Injection System)
Component:
FUB (Fuse Block)
Manufacturer:
W120 (Westinghouse)
Part Number TBAF3