05000282/LER-2006-001, Regarding Unit 1 Reactor Trip
| ML063380298 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 07/31/2006 |
| From: | Thomas J. Palmisano Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-PI-06-064 LER 06-001-00 | |
| Download: ML063380298 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B) |
| 2822006001R00 - NRC Website | |
text
NMC Prairie Island Nuclear Generating Plant Committed to Nuclear Ex ncelxe Operated by Nuclear Management Company, LLC July 31, 2006 L-PI-06-064 10 CFR 50.73 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Unit 1 Docket 50-282 License No. DPR-42 LER 1-06-01, Unit 1 Reactor Trip, Supplement 1 Supplement 1 to the Licensee Event Report (LER) for this occurrence is attached.
Nuclear Management Company, LLC (NMC) notified the NRC of this event, as required by 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A), on April 14, 2006. The original LER was submitted on June 13, 2006. This supplement incorporates the results of NMC's root cause evaluation of this event. Please contact us if you require additional information related to this event.
Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.
This letter completes the commitment made in the original LER to submit a supplement to this LER after the associated root cause evaluation was completed.
Thomas J. Palmisano Site Vice President, Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC Enclosure cc:
Administrator, Region III, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC Glenn Wilson, State of Minnesota 1717 Wakonade Drive East
- Welch, Minnesota 55089-9642 Telephone: 651.388.1121 In.
ENCLOSURE LICENSEE EVENT REPORT 1-06-01, Supplement 1 3 pages follow
NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 6-30-2007 COMMISSION (6-2004)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Prairie Island Nuclear Generating Plant Unit 1 05000 282 1
of 3
TITLE (4)
Unit 1 Reactor Trip EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER I NO MO DAY YEAR 4
14 06 06 01 1
7 31 06 FACILITYNAME DOCKETNUMBER OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 3: (Check all that apply) (11)
MODE (9) 20.2201 (b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B) 50.73(a)(2)(ix)(A)
POWER 20.2201(d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LEVEL (110) 100 20.2203(a)(1) 50.36(c)(1)(i)(A)
X 50.73(a)(2)(iv)(A) 73.71(a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 73.71(a)(5) 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)
OTHER 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C)
Specify in Abstract below or in 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)
LICENSEE CONTACT FOR THIS LER (12)
NAME 1
TELEPHONE NUMBER (Include Area Code)
Jeff Kivi 651.388.1121 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
REPORTABLE MANU-REPORTABLE MANU-TO EPIX
CAUSE
SYSTEM COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM COMPONENT FA CTURER Aging SD MO 1075 Y
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR SX SUBMISSIONSSIN TYES (if yes, complete EXPECTED SUBMISSION DATE).
X NO DATE (15) 1 1
1 ABSTRACT On April 14, 2006, Prairie Island Nuclear Generating Plant (PINGP) Unit 1 was operating at 100% power. At approximately 1425 CDT, an 11 FEEDWATER PUMP LOCKED OUT annunciator was received in the control room. Unit 1 operators responded per the alarm response procedure and manually tripped the reactor. The trip was uncomplicated and all systems operated as expected and operator response and recovery actions were as expected.
Initial investigation of the cause of the 11 Feedwater Pump trip determined the feedwater pump tripped because the 11 Condensate Pump had tripped. The 11 Condensate Pump motor was shipped off site for repairs and the stator windings were found to have grounded. The root cause evaluation (RCE) of this event determined the condensate pump trip was caused by degraded motor insulation due to aging and environmental conditions. The RCE further determined that the organizational root cause of the condensate pump motor trip was a lack of an adequate long range planning and budgeting process to prioritize and budget large motor maintenance.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER 2 LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION Prairie Island Nuclear Generating Plant Unit 1 05000282 NUMBER NUMBER 2 of 3 06 01 1
TEXT (If more space is required. use additional copies of NRC Form 366A) (17)
EVENT DESCRIPTION
On April 14, 2006, Prairie Island Nuclear Generating Plant (PINGP) Unit 1 was operating at 100%
power. At approximately 1425 CDT, an 11 FEEDWATER' PUMP 2 LOCKED OUT annunciator was received in the control room. Unit 1 operators responded per the alarm response procedure and manually tripped the reactor. The auxiliary feedwater 3 pumps started automatically in response to the low narrow range steam generator level, which was caused by shrink resulting from the reactor trip.
The trip was uncomplicated and all systems operated as expected and operator response and recovery actions were as expected.
EVENT ANALYSIS
The trip of the Unit 1 reactor and the actuation of the auxiliary feedwater system are required to be reported per 10 CFR 50.73(a)(2)(iv)(A).
Impact on Safety System Functional Failure Performance Indicator The affected condensate and feedwater pumps have no active safety function. All other systems performed as expected during the event. Therefore, this event does not represent a loss of safety function. Consequently, this event is not reportable per 10CFR 50.73(a)(2)(v).
SAFETY SIGNIFICANCE
The plant was stabilized in Mode 3 after the trip with all systems performing as expected in response to the reactor trip. Therefore, this event did not affect the health and safety of the public.
CAUSE
Initial investigation of the cause of the 11 Feedwater Pump trip determined the feedwater pump tripped because the 11 Condensate Pump had tripped. Troubleshooting identified the cause of the condensate pump trip to be a ground between the 11 Condensate 4 Pump and Bus 13. The condensate pump motor was determinated and a zero ohm ground was measured on the motor. The motor was shipped off site for repairs and the stator windings were found to have grounded.
1 EIIS System Code: SJ 2 EllS Component Identifier: P 3 EIIS System Code: BA 4 EIIS System Code: SD
I I bU.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION Prairie Island Nuclear Generating Plant Unit 1 05000282 NUMBER NUMBER 3 of 3 06 01 1
TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
NMC conducted a root cause evaluation (RCE) and determined that the equipment cause of the condensate pump motor trip was degraded motor insulation due to aging and environmental conditions. The RCE further determined that the organizational root cause of the condensate pump motor trip was a lack of an adequate long range planning and budgeting process to prioritize and budget large motor maintenance.
CORRECTIVE ACTION
Interim Actions:
- 1. NMC performed a baseline off-line monitoring for Unit 1 large balance of plant motors in the May 2006 (1R24) refueling outage. All data was in acceptable ranges.
Planned Actions:
- 2. Rewind all Unit 1 and Unit 2 condensate pump motors with Class F insulation.
- 3. Develop a Large Motor Plan for Prairie Island that includes frequency and scope of testing, preventative maintenance and frequency of major maintenance activities.
- 4. Revise long range plan and budgets to include major maintenance activities.
- 5. Investigate trip logic for the condensate pumps to determine the feasibility of modifying the logic to prevent a unit trip following a condensate pump trip.
PREVIOUS SIMILAR EVENTS
Both Unit 1 and Unit 2 have experienced unplanned reactor trips in the past, however, the most recent unplanned reactor trip of either unit occurred in 2002.