05000293/LER-2008-004, Regarding High Pressure Coolant Injection System Inoperable Due to Undervoltage Relay Failure in Valve Power Supply Circuit
| ML083590345 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/10/2008 |
| From: | Bronson K Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 08-004-00 | |
| Download: ML083590345 (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)(i)(B), Prohibited by Technical Specifications |
| 2932008004R00 - NRC Website | |
text
Entergy Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 Kevin H. Bronson Site Vice President December 10, 2008 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555
SUBJECT:
Entergy Nuclear Operations, Inc.
Pilgrim Nuclear Power Station Docket No.: 50-293 License No.: DPR-35 Licensee Event Report 2008-004-00 LETTER NUMBER: 2.08.065
Dear Sir or Madam:
The enclosed Licensee Event Report (LER) 2008-004-00, "HPCI System Inoperable Due to Undervoltage Relay Failure in Valve Power Supply Circuit" is submitted in accordance with 10 CFR 50.73.
This letter contains no commitments.
Please do not hesitate to contact Mr. Joseph R. Lynch, (508) 830-8403, if there are any questions regarding this submittal.
Sincerely, Kevin H. Bronson FXM/dl Enclosure cc:
Mr. James S. Kim, Project Manager Plant Licensing Branch I-1 Division of Operator Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission One White Flint North O-8C2 11555 Rockville Pike Rockville, MD 20852 INPO Records 700 Galleria Parkway Atlanta, GA 30399-5957 Mr. Samuel J. Collins Regional Administrator, Region 1 U.S. Nuclear Regulator Commission 475 Allendale Road King of Prussia, PA 19406 Senior Resident Inspector Pilgrim Nuclear Power Station
- 1.
NRC Form 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104
, 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)
PILGRIM NUCLEAR POWER STATION 05000-293 1 of 4 TITLE (4)High Pressure Coolant Injection System Inoperable Due to Undervoltage Relay Failure in Valve Power Supply Circuit EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
SEQUENTIAL NUMBER REVISION FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER MONTH DAY YEAR N/A 05000 FACILITY NAME DOCKET NUMBER 10 21 2008 2008 004 00 12 10 2008 N/A 05000 E
OPERATING 1 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR: (Check one or more) (11)
MODE (9)
N 20.2201 (b) 22.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
POWER 0'
22.2202(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A)
LEVEL (10)_
100 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(3)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(3)(1)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x)
I 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)
X 50.73(a)(2)(v)(D)
Specify in Abstract below Ior in NRC Form 366A LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER (Include Area Code)
Joseph Lynch - Licensing Manager 508-830-8403 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
REPORTABLE REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER TO EPIX
CAUSE
SYSTEM COMPONENT MANUFACTURER TO EPIX B
El 27 C7770 Y
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR YES I
NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE)
DATE(15)
ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On October 21, 2008, at 1944 hours0.0225 days <br />0.54 hours <br />0.00321 weeks <br />7.39692e-4 months <br />, with the plant operating at 100% power, the Control Room received a Motor Control Center (MCC) D9 trouble alarm. Operators noted that the indicator light for the High Pressure Coolant Injection (HPCI) Injection Valve MO-2301-8 was extinguished. Investigation at the MCC revealed that the 125V DC valve control power circuit for the normally closed HPCI Injection Valve MO-2301-8 was deenergized due to failure of the undervoltage relay in the 250V DC power feed to the valve motor operator. HPCI was declared inoperable and applicable Technical Specification (TS) Limiting Conditions for Operation (LCO) were applied. The undervoltage relay was replaced, and HPCI was returned to operable standby status at 0404 hours0.00468 days <br />0.112 hours <br />6.679894e-4 weeks <br />1.53722e-4 months <br /> on October 22, 2008.
The most probable root cause of the event was identified to be an isolated premature failure of the undervoltage relay due to a manufacturing defect.
Immediate corrective actions taken included the replacement of the undervoltage relay. Corrective actions planned include destructive failure analysis of the undervoltage relay; and engineering evaluation of installed DC powered motor operated valve undervoltage relays and associated preventative maintenance requirements.
The event posed no threat to public health and safety.
NRC FORM 366U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
SEQUENTIAL REVISION YEAR NUMBER NUMBER PILGRIM NUCLEAR POWER STATION 05000-293 2008 004 00 2 of 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
BACKGROUND The Pilgrim Station Core Standby Cooling Systems (CSCS) consist of the High Pressure Coolant Injection (HPCI) System, Automatic Depressurization System (ADS), Residual Heat Removal (RHR) System Low Pressure Injection (LPCI) mode, and Core Spray (CS) System. The HPCI System is designed to pump water into the reactor vessel for high pressure core cooling. Although not part of the CSCS, the Reactor Core Isolation Cooling (RCIC) System is also designed to pump water into the reactor vessel for high pressure core cooling, similar to the HPCI System.
The HPCI System injection piping includes two motor operated valves, MO-2301-8 and MO-2301-9, and a check valve, CK-2301-7. Valve MO-2301-8 is normally closed and is designed to automatically open on a system initiation signal. Motor Control Center (MCC) D9 provides 250V DC power to MO-2301-8. A separate 125V DC control power source is used in the valve's control power circuit. Valve position indication is also powered by the same 125V DC control power circuit.
For valve motor operator protection purposes, an undervoltage relay is installed in the 250V DC valve power feed circuit. If an undervoltage condition exists, the relay will deenergize and open contacts in the 125V DC valve control circuit to denergize control power. Without valve control power, MO-2301-08 will not open or close in response to automatic initiation signals.
Technical Specification (TS) 3.5.C.1 specifies HPCI System operability when irradiated fuel is in the reactor vessel, reactor pressure is greater than 150 psig, and reactor coolant temperature is greater than 3650 F. TS 3.5.C.2 specifies a 14-day Limiting Condition for Operation (LCO) from and after the date the system is made or found inoperable for any reason provided that during such 14 days all active components of the ADS, RCIC System, RHR System (LPCI mode), and Core Spray Systems are operable. 'TS 3.5.C.3 specifies a 24-hour timeframe for the initiation of an orderly shutdown (to a cold shutdown condition) if the requirements of TS 3.5.C cannot be met.
The CSCS and the RCIC Systems were operable prior to failure of HPCI Injection Valve MO-2301-8.
EVENT DESCRIPTION
On October 21, 2008, at 1944 hours0.0225 days <br />0.54 hours <br />0.00321 weeks <br />7.39692e-4 months <br />, with the plant operating at 100% power and the mode switch in RUN, the Control Room received a Motor Control Center (MCC) D9 trouble alarm. Operators noted that the indicator light for the HPCI Injection Valve MO-2301-8 was extinguished. Investigation at the MCC revealed that the 125V DC valve control power circuit for the normally closed HPCI Injection Valve MO-2301-8 was deenergized due to failure of the undervoltage relay in the 250V DC power feed to the valve motor operator. HPCI was declared inoperable and applicable TS LCO requirements were applied. The undervoltage relay was replaced, and HPCI was returned to operable, standby status at 0404 hours0.00468 days <br />0.112 hours <br />6.679894e-4 weeks <br />1.53722e-4 months <br /> on October 22, 2008.
The NRC was notified of the event at 2345 hours0.0271 days <br />0.651 hours <br />0.00388 weeks <br />8.922725e-4 months <br /> on October 21, 2008 via Event Report Number 44587.U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE 3 SEQUENTIAL REVISION YEAR NUMBER NUMBER PILGRIM NUCLEAR POWER STATION 05000-293 2008 004 00 3 of 4
CAUSE
The most probable root cause (RC) of this event was identified to be an isolated premature failure of the Cutler Hammer Model Number BFD33T undervoltage relay due to a manufacturing defect.
CORRECTIVE ACTION
Corrective actions taken included replacement of the undervoltage relay.
Corrective action planned include the following:
Undervoltage relay destructive failure analysis.
Engineering evaluation of installed DC power motor operated valve undervoltage relays and associated preventative maintenance requirements.
These corrective actions are being tracked by the site Corrective Action Program (CAP).
SAFETY CONSEQUENCES
The condition posed no threat to public health and safety.
The event occurred during normal power operation while at 100% power with the mode switch in the RUN position. The reactor vessel pressure was approximately 1030 psig with reactor water temperature at saturation temperature for that pressure.
The Core Standby Cooling Systems (CSCS) consist of the HPCI System, Automatic Depressurization System (ADS), Core Spray System, and the Residual Heat Removal (RHR) System in the Low Pressure Core Coolant Injection (LPCI) mode. Although not part of the CSCS, the Reactor Core Isolation Cooling (RCIC) System is capable of providing water to the reactor vessel for high pressure core cooling, similar to the HPCI System.
The HPCI System provides high pressure makeup water to the reactor vessel after isolation of the vessel.
The HPCI System was inoperable for approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and 30 minutes due to the loss of 125V DC control power to HPCI Injection Valve MO-2301-8. During this time frame the ADS, Core Spray, RHR, and RCIC Systems were operable and met the 14 day Technical Specification 3.5.C.2 limiting condition for operation requirements for operating the plant with an inoperable HPCI System. These systems provided capability to supply makeup water to the vessel and ensured adequate core cooling while the HPCI System was not operable. The HPCI System was restored to operable status, there was no long term safety significance associated with the event.U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
SEQUENTIAL REVISION YEAR NUMBER NUMBER PILGRIM NUCLEAR POWER STATION 05000-293 2008 004 00 4 of 4
REPORTABILITY
This report was submitted in accordance with 10 CFR 50.73(a)(2)(v)(D).
SIMILARITY TO PREVIOUS EVENTS A review was conducted of previously issued Pilgrim Station LERs. The review focused on LERs that involved a similar event where system function was lost due to loss of control power to motor operated valve control circuits. The review identified similar events where HPCI System valve function was lost:
LER-2002 "High Pressure Injection System Inoperable due to Fuse Failure," LER-2004 "High Pressure Injection System Fuse Failure While System Inoperable for Planned Maintenance and Testing,"
and LER 2005 "HPCI System Inoperable Due to Fuse Failure in Motor Operated Valve Control Circuit." No LERs were located which involved loss of system function due to failure of the DC power undervoltage relays.
ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) CODES The EIIS codes for Components and Systems referenced in this report are as follows:
COMPONENTS CODES Valve, Injection INV Relay, Undervoltage 27 SYSTEMS High Pressure Coolant Injection (HPCI)'
BJ DC Power System - Class 1 E EJ