05000282/LER-2012-002, For Prairie Island, Unit 1, Regarding Unplanned Actuation of 121 Motor Driven Cooling Water Pump
| ML12152A189 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 05/30/2012 |
| From: | Davison K Xcel Energy, Northern States Power Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-PI-12-035 LER 12-002-00 | |
| Download: ML12152A189 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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 10 CFR 50.73(a)(2)(iv)(B), System Actuation |
| 2822012002R00 - NRC Website | |
text
@ Xcel Energye May 30,2012 L-PI-12-035 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 Renewed License No. DPR-42 LER 50-28212012-002-00, Unplanned Actuation of 121 Motor Driven Cooling Water Pump Northern States Power Company, a Minnesota corporation (hereafter NSPM), doing business as Xcel Energy, herewith encloses Licensee Event Report (LER) 50-2821201 2-002-00.
On April 2, 2012, while Prairie Island Nuclear Generating Plant (PINGP) Unit 1 was operating at 100% power, 121 Motor Driven Cooling Water Pump (MDCLP) auto started. The 121 MDCLP auto started while shutting down 22 Diesel Driven Cooling Water Pump (DDCLP).
Five cooling water (CL) pumps are connected to a common pump discharge header that directs CL flow into two separate headers. There are three motor driven pumps (121 MDCLP, 11 CLP and 21 CLP) and two diesel driven pumps (12 DDCLP and 22 DDCLP). The Equipment Cause Evaluation (ECE) determined that when only one motor driven pump is supplying both CL headers while removing 12 or 22 DDCLP, the momentary drop in header pressure can auto start 121 MDCLP.
Summary of Commitments This letter contains no new commitments and no changes to existing commitments.
'~evin Davison Director, Site Operations, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, PINGP, USNRC Resident Inspector, PINGP, USNRC Department of Commerce, State of Minnesota 1717 Wakonade Drive East Welch, Minnesota 55089-9642 Telephone: 651.388.1 121
ENCLOSURE LICENSEE EVENT REPORT 50-2821201 2-002-00 3 Pages Follow
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digitstcharacters for each block)
APPROVED BY OMB NO 3150-0104 EXPIRES 1013112013
, the NRC may not conduct or sponsor, and a person is not required to respond to, the infonabon collection
- 1. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1
- 2. DOCKET NUMBER 05000 282
- 3. PAGE OF 3
- 4. TITLE Unplanned Actuation of 121 Motor Driven Cooling Water Pump
- 5. EVENT DATE
- 6. LER NUMBER SEQUENTIAL REV YEAR I NUMBER I NO 2012 - 002 - 00 MONTH 04
- 12. LICENSEE CONTACT FOR THIS LER
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check allthat apply)
C]
20.2201(b)
C]
20.2203(a)(3)(i)
C]
50.73(a)(2)(i)(C)
C]
50.73(a)(2)(vii)
C]
20.2201(d)
[7 20.2203(a)(3)(ii)
C]
50.73(a)(2)(ii)(A) [7 50.73(a)(2)(viii)(A)
C]
20.2203(a)(I)
C]
20.2203(a)(4)
C]
50.73(a)(2)(ii)(B) C]
50.73(a)(2)(viii)(B)
C]
20.2203(a)(2)(i)
C]
50.36(c)(l)(i)(A)
[7 50.73(a)(2)(iii)
C]
50.73(a)(2)(ix)(A)
[7 20.2203(a)(2)(ii)
[7 50.36(c)(l)(ii)(A) a 50.73(a)(2)(iv)(A) C]
50.73(a)(2)(x)
C]
20.2203(a)(2)(iii)
[7 50.36(~)(2)
C]
50.73(a)(2)(v)(A) C]
73.71(a)(4)
C]
20.2203(a)(2)(iv)
C]
50.46(a)(3)(ii)
[7 50.73(a)(2)(v)(B) C]
73.71(a)(5) 20.2203(a)(2)(v)
C]
50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C) C]
OTHER C]
20.2203(a)(2)(vi)
C]
50,73(a)(2)(i)(B)
C]
50,73(a)(2)(v)(D)
Spec~fy in Abstract below or in 9. OPERATING MODE Mode I
- 10. POWER LEVEL 100%
DAY 02 NAME Sam J. DiPasquale, P.E.
YEAR 2012
- 7. REPORT DATE TELEPHONE NUMBER (Include Area Code) 651.388.1 121 x7350 MONTH 05
- 8. OTHER FACILITIES INVOLVED FACILITY NAME FACILITY NAME DAY 30 DOCKET NUMBER DOCKET NUMBER
CAUSE
YEAR 2012 SYSTEM
- 14. SUPPLEMENTAL REPORT EXPECTED 0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE).
O NO COMPONENT ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 2, 2012, while Prairie Island Nuclear Generating Plant (PINGP) Unit 1 was operating at 100% power, 121 Motor Driven Cooling Water Pump (MDCLP) auto started. The 121 MDCLP auto started while shutting down 22 Diesel Driven Cooling Water Pump (DDCLP).
Five cooling water (CL) pumps are connected to a common pump discharge header that directs CL flow into two separate headers. There are three motor driven pumps (121 MDCLP, 11 CLP and 21 CLP) and two diesel driven pumps (12 DDCLP and 22 DDCLP). The Equipment Cause Evaluation (ECE) determined that when only one motor driven pump is supplying both CL headers while removing 12 or 22 DDCLP, the momentary drop in header pressure can auto start 121 MDCLP.
NRC FORM 366 (10-2010)
MANU-FACTURER YEAR
- 15. EXPECTED SUBMISSION DATE REPORTABLE TO EPlX MONTH DAY
CAUSE
SYSTEM COMPONENT MANU-FA CTURER REPORTABLE TO EPlX
EVENT DESCRIPTION LICENSEE EVENT REPORT (LE R)
U.S. NUCLEAR REGULATORY COMMISSION (1 0-201 0)
CONTINUATION SHEET On April 2, 2012, while Prairie Island Nuclear Generating Plant (PINGP) Unit 1 was operating at 100% power, Operations performed a post-maintenance test (PMT) of the 22 Diesel Driven Cooling Water pump' (DDCLP) as part of a Work Order (WO) at approximately 02:24 CDT.
- However, because no work had been performed on the pump and the monthly surveillance procedure (SP) was not scheduled, 22 DDCLP was operated per Operations procedure C35, Cooling Water. The 121 Motor Driven Cooling Water Pump (MDCLP) auto started while shutting down 22 DDCLP even though 11 Cooling Water Pump (CLP) was running. The manual or automatic actuation of the CL system (equivalent to an emergency service water system) is reportable under 10 CFR 50.73(a) (2)(iv) (A).
- 1. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1
EVENT ANALYSIS
At PINGP, the Cooling Water (CL) system2 is a shared system common to both Units (1 and 2) that 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 non-safety related components.
- 2. DOCKET NUMBER 05000 282 Five CL pumps are connected to a common pump discharge header that directs CL flow into two separate headers. There are three motor driven pumps (121 MDCLP, 11 CLP and 21 CLP) and two diesel driven pumps (12 DDCLP and 22 DDCLP). The 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.
On April 2, 2012, 121 MDCLP was not aligned as a safeguards replacement pump. An autostart of 121 MDCLP occurred even though 11 CLP was running. Due to previous auto starts of 121 MDCLP, step 7.9.1.1 was added to SP 1106B (22 DIESEL COOLING WATER PUMP MONTHLY TEST), that states, "IF only one (1) motor driven cooling water pump is running, THEN start an additional motor driven cooling water pump per C35.
- 6. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO 2012 -
002
- - 00 Procedure C35 was previously revised with a note that states an additional cooling water pump may be required. The additional step in SPI 106B to require starting an additional pump prior to shutting down the 22 DDCLP provides more definitive guidance than C35 in this situation.
- 3. PAGE 2 OF 3
SAFETY SIGNIFICANCE
The 121 MDCLP and the two DDCLPs automatically start on low cooling water header pressure. The water header pressure setpoint that starts the 121 MDCLP is slightly higher to ensure that it will 1 Ells Component Identifier: P Ells System Code: BI
automatically start before the DDCLPs. For this event, the 121 MDCLP started on the low pressure signal as expected. The 121 MDCLP and other equipment operated as intended during the event, therefore, there were no radiological, environmental, or industrial impacts associated with this event and PlNGP did not affect the health and safety of the public. This event 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. LICENSEE EVENT REPORT (LER)
U.S. NUCLEAR REGULATORY COMMISSION (1 0-201 0)
CONTINUATION SHEET
CAUSE
- 1. FACILITY NAME Prairie Island Nuclear Generating Plant Unit 1 The Equipment Cause Evaluation (ECE) determined that low pressure in the header was reached due to having only one pump in service at the time of removing 22 DDCLP. If only one motor driven pump is supplying both headers while removing 12 or 22 DDCLP, the momentary drop in header pressure can auto start 121 MDCLP.
CORRECTIVE ACTION
- 2. DOCKET NUMBER 05000 282 The C35 Operating Procedure guidance and instruction will be revised to align with the changes made to the Surveillance Procedures.
PREVIOUS SIMILAR EVENTS
- 6. LER NUMBER YEAR SEQUENTIAL REV NUMBER NO 2012 -
002
- - 00 LER 1-09-02 was submitted on May 18, 2009. This LER reported the automatic actuation of 121 MDCLP when it was aligned as a safeguards pump. The actuation occurred following planned maintenance of the 12 DDCLP. During post maintenance testing, 12 DDCLP was tripped per procedure. This resulted in a transient of the cooling water system pressure. The momentary drop in pressure was large enough to automatically start the 121 MDCLP while it was aligned for safeguards service.
- 3. PAGE 3 OF 3 LER 50-2821201 1-001-02 was submitted on October 7, 201 1. The LER reported that an auto start of the 121 Motor Driven Cooling Water Pump (MDCLP) when not aligned as a safeguards replacement pump is included in the list of systems in 10 CFR 50.73(a)(2)(iv)(B). As a result, an actuation of the 121 MDCLP on 12/23/2010 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.