05000282/LER-2016-006, Regarding 121 Motor Driven Cooling Water Pump Auto Start
| ML17046A656 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/15/2017 |
| From: | Northard S Northern States Power Co, Xcel Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-PI-17-003 LER 16-006-00 | |
| Download: ML17046A656 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(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) |
| 2822016006R00 - NRC Website | |
text
Xcel Energy@
FEB 1 5 2017 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 Prairie Island Nuclear Generating Plant 1717 Wakonade Drive East Welch. MN 55089 L-PI-17-003 10 CFR 50.73 Licensee Event Report 50-282/2016-006-00, 121 Motor Driven Cooling Water Pump Auto Start Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), encloses Licensee Event Report (LER) 50-282/2016-006-00, 121 Motor Driven Cooling Water Pump Auto Start.
If there is any question or if any additional information is needed, please contact Frank Sienczak, at 651-267-1740.
Summary of Commitments This letter contains no new commitments and no changes to existing commitments
~~
Scott Northard Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company-Minnesota
Enclosures:
cc:
Regional Administrator, Region Ill, USNRC Project Manager, Prairie Island Nuclear Generating Plant, USNRC Resident Inspector, Prairie Island Nuclear Generating Plant, USNRC Department of Commerce, State of Minnesota
Document Control Desk Page 2 ENCLOSURE 1 LICENSEE EVENT REPORT 50-282/2016-006-00 4 Pages Follow
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1.
PAGE Prairie Island Nuclear Generating Plant 05000-282 1 OF 4
~*TITLE 121 Motor Driven Cooling Water Pump Auto Start
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR Prairie Island Unit 2 05000-306 FACILITY NAME DOCKET NUMBER 12 18 2016 2016
- - 006
- - 00 2
15 2017 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
Unit 1 Mode 1 D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
Unit 2 Mode 1 D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A)
IX! 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
- 10. POWER LEVEL D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5)
Unit 1 100%
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1)
Unit 2 100%
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT
~ELEPHONE NUMER (Include Area Code)
Frank Sienczak, Senior Licensing Engineer 651-267-1740
- 13. COMPLETE ONE UNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANU*
REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TOEPIX B
FK BKR ASEA Yes
- 14. SUPPLEMENTAL REPORT EXPECTED 15.EXPECTED MONTH DAY YEAR D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) rgj NO SUBMISSION DATE
~BSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On December 18, 2016, at 0818 COT, the Prairie Island Nuclear Generating Plant (PINGP) had a fire in the PINGP Switch Yard due to 8H8 Breaker-CT (Current Transformer) catastrophic failure. During the event, 121 Motor Driven Cooling Water Pump (MDCLP) auto-started on low header pressure (80 psi) as designed, and supplied load to the Cooling Water (CL) Header to increase header pressure. This event is reportable under 10 CFR 50. 73(a)(2)(iv)(A) as an event that resulted in automatic actuation of an emergency service water system.
The cause of the 121 MDCLP auto-start was a low-pressure transient in the cooling water pump discharge header that was caused by the trip of the Containment & Auxiliary Building Chiller. When the chiller tripped, Unit 2 Containment Fan Coil units automatically swapped to cooling water. This additional load on the CL system, which caused system pressure to drop below 80 psi. The health and safety of the public was not at risk.
NRC FORM 366 (06-2016)
DESCRIPTION OF EVENT
SEQUENTIAL NUMBER 006 REV NO.
00 On December 18, 2016, at 0818 COT, the Prairie Island Nuclear Generating Plant (PINGP) had a fire in the PINGP Switch Yard due to 8H8 Breaker-CT (Current Transformer) catastrophic failure. As the result of the 8H8 breaker fire, adjacent breakers 8H9, 8H7 and incoming lines from North Rochester (NRH) and Red Rock 2 (RRK2) were tripped and isolated from Bus 1 and Bus 2. Approximately 6 sec after the 8H8 CT catastrophic failure, automatic reclosing action to close the 8H7 breaker was initiated to place Red Rock 2 in service but failed. Approximately 15 sec after the 8H8 CT catastrophic failure, automatic reclosing action to close the 8H9 breaker was initiated to place North Rochester in service, which resulted in Bus 2 lock out (delay energized) due to relay 8782S/345kV actuation. It was identified that this was a relay mis-operation.
At the time of the event, the non-safety related 11 Cooling Water (CL) pump 1 was running to supply load to the CL header. Low CL header pressure was caused by a trip of the Containment & Aux Building Chiller (ZX)
System. The trip of the ZX system was caused by the electrical transient. The Containment Fan Coil Units (CFCU's) can be cooled by either ZX or by the safety related CL source. At the time of this event, the Unit 1 CFCU's were aligned to the CL system for cooling. The Unit 2 CFCU's were aligned to the ZX system. When the ZX Chiller tripped, the Unit 2 CFCU's lost ZX flow, and automatically swapped to the safety related cooling of the CL system, as designed. This caused an increased demand on the CL system, which caused the 121 MDCLP to auto-start on low header pressure (at 80 psi) as designed.
EVENT ANALYSIS
The PINGP CL System2 is a shared system for Units 1 and 2 and provides a heat sink for the removal of process and operational heat from safety-related components during a Design Basis Accident or transient.
During normal operation and shutdown, the CL System also provides this function for various safety-related and nonsafety-related components.
Five CL pumps are connected to a common pump discharge header that directs CL flow into two separate headers: three motor-driven pumps and two diesel-driven pumps. 121 MDCLP can function as a safeguards replacement when a diesel driven pump is taken out of service. In this configuration, the pump is aligned manually to the appropriate train of safeguards power and motor-operated valves are administratively disabled in accordance with technical specifications.
SAFETY SIGNIFICANCE
There was no radiological, environmental, or industrial impact associated with the 121 MDCLP auto-start, and the health and safety of the public were not affected. The auto-start of the 121 Motor Driven Cooling Water Pump did not challenge nuclear safety as all plant systems responded as designed; therefore, this event does not represent a safety system functional failure for Unit 1 or Unit 2.
11EEE Component Code-P 2EIIS System Code - Bl Page 2 of 4 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR Prairie Island Nuclear Generating Plant 05000-282 2016
CAUSE
SEQUENTIAL NUMBER 006 REV NO.
00 The cause of the 121 MDCLP auto-start was a low-pressure transient in the cooling water pump discharge header was caused by the trip of the ZX Chiller and the additional load on the CL system that reduced CL header pressure to the 121 MDCLP auto-start setpoint.
CORRECTIVE ACTION COMPLETED When the ZX Chiller tripped, the Unit 2 CFCU's lost ZX flow, and automatically swapped to the safety related cooling of the CL system, as designed. Since the system operated as expected, thus there are no corrective actions.
PREVIOUS SIMILAR OCCURRENCES LER 1-09-02, Unplanned Safety Related Actuation of 121 Cooling Water Pump (Agencywide Documents Access and Management System (ADAMS) Accession Number ML091390396). On 3/19/2009, 121 MDCLP auto-started when 12 DDCLP was tripped in accordance with procedure resulting in a transient of the cooling water system pressure. The momentary drop in pressure was large enough to auto-start the 121 MDCLP while it was aligned for safeguards service.
LER 50-282/2011-001-02, Unplanned Actuation of 121 Motor Driven Cooling Water Pump, Supplement 2 (ADAMS Access Number ML112840145). On 12/23/2010, the 121 MDCLP auto-started due to low header pressure. This low pressure condition was due to the failure of a header gasket on a non-safeguards chiller.
The gasket failure was due to an over-torque condition, gasket material, and the conditions under which the chiller was operating at the time of the failure. The 121 MDCLP was not aligned as a safeguards replacement pump and auto-started. The actuation of the 121 MDCLP was determined to be reportable under 10 CFR 50.
73(a)(2)(iv)(A). Corrective actions to resolve the issue included performing a Cooling Water System review to determine methods and any single point vulnerabilities that can be performed to minimize the potential for auto-starts of a cooling water pump. Operating procedures were evaluated to determine if procedural or operation period changes can be made to reduce the likelihood of auto-starting a Cooling Water Pump.
LER 50-282/2012-002-00, Unplanned Actuation of 121 Motor Driven Cooling Water Pump (ADAMS Accession Number ML12152A189). On 4/2/2012, while PINGP Unit 1 was operating at 100% power, 121 MDCLP auto-started while shutting down 22 DDCLP, this caused a low pressure condition in the header and the auto-start of the pump. The corrective action was to revise operating procedure C35 to ensure two MDCLPs are running prior to stopping the DDCLP.
LER 50-282/2016-002-00, Listed System Actuation - Motor-Driven Cooling Water Pump Auto-Start (ADAMS Accession Number ML16085A181). On 1/29/2016, PINGP performed a planned overspeed post-maintenance test (PMT) of 22 Diesel Driven Cooling Water Pump in accordance with plant maintenance procedure. During the overspeed trip test PMT, 22 DDCLP tripped as expected and 121 MDCLP unexpectedly started automatically on low pressure in the cooling water pump discharge header.
Page 3 of 4 (06-2016)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. LER NUMBER YEAR Prairie Island Nuclear Generating Plant 05000-282 2016 SEQUENTIAL NUMBER 006 REV NO.
00 LER 50-282/2016-005-00, 121 Motor Driven Cooling Water Pump Auto Started (ADAMS Accession Number ML16281A208). On 8/21/2016, PINGP 2RY Transformer locked out. 121 Motor Driven Cooling Water Pump (MDCLP) stopped due to loss of power and then automatically restarted when sequenced by the load sequencer. The pump auto started on low pressure in the cooling water pump discharge header.