05000266/LER-2015-006-01, Regarding Automatic Reactor Trip - Revision
| ML15362A365 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 12/28/2015 |
| From: | Mccartney E Point Beach |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC 2015-0077 LER 15-006-01 | |
| Download: ML15362A365 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 2662015006R01 - NRC Website | |
text
ENERGY December 28, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 1 Docket 50-266 Renewed License No. DPR-24 Licensee Event Report 266/2015-006-01 Unit 1 Automatic Reactor Trip - Revision POINT BEACH NRC 2015-0077 10 CFR 50.73 Enclosed is Licensee Event Report (LER) 266/2015-006-01 for Point Beach Nuclear Plant, Unit 1. NextEra Energy Point Beach, LLC is providing this revised LER regarding the Unit 1 automatic reactor trip.
This letter contains no new regulatory commitments.
If you have any questions please contact Mr. Bryan Woyak, Licensing Manager, at 920/755-7599.
Very truly yours, NextEra Energy Point Beach, LLC Eric McCartney Site Vice President Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014\\
, the NRC may not conduct or sponsor, and a person Is not required to respond to, the infonnation collection.
- 6. LERNUMER YEAR I SEQUENTIAL I NUMBER REV NO.
2015 -
006 01
- 3. PAGE 2
OF 2
At 1912 on November 28, 2015 with Unit 1 in MODE 1 at full power, an automatic reactor trip was actuated as the result of a failure of the Main Generator Automatic Voltage Regulator (AVR). All control rods fully inserted into the core. The Auxiliary Feedwater Pumps started as expected on low steam generator level. The Auxiliary Feedwater system was secured and decay heat removal was provided by the Condenser Steam Dumps utilizing the Main Feedwater system. All other safety systems functioned as designed.
The Unit 1 Main Generator AVR was repaired, returned to service and the unit returned to full power operations.
This 60-day licensee event report is being submitted in accordance with the requirements of 10 CFR 50. 73(a)(2)(iv)(A) for I the automatic actuation of the reactor protection system and auxiliary feedwater system.
Cause of the Event
The cause of the automatic reactor trip was due to the failure of an isolation transducer module in the Main Generator AVR.
Analysis of the Event
Troubleshooting activities completed as part of the post trip investigation identified a failed isolation transducer module within the main generator AVR. The main generator AVR isolation transducer module failure resulted in an indicated over excitation protection set point being exceeded causing a generator lockout. The generator lockout caused the turbine to trip. The reactor tripped as a result of the turbine trip.
Corrective Actions
The Unit 1 Main Generator AVR was repaired, returned to service and the unit returned to full power operations.
Safety Significance
The event was determined to be of very low safety significance. During the event and subsequent recovery actions, there was no loss of any safety systems, structures or components. All control rods fully inserted into the core as designed to control reactivity and temperature of the core. This event had no impact on the safety of the core. The Auxiliary Feedwater Pumps started as expected on low steam generator level. The Auxiliary Feedwater system was secured and decay heat removal was provided by the Condenser Steam Dumps utilizing the Main Feedwater system. There was no impact on the health and safety of the public as a result of this event.
Similar Events
There have not been similar events of automatic reactor trips in the past three years.
Component Failure Data
Main Generator Automatic Voltage Regulator DC-DC Isolation Transducer Module Style 1A96166G11 -Cutler-Hammer
ENERGY December 28, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 1 Docket 50-266 Renewed License No. DPR-24 Licensee Event Report 266/2015-006-01 Unit 1 Automatic Reactor Trip - Revision POINT BEACH NRC 2015-0077 10 CFR 50.73 Enclosed is Licensee Event Report (LER) 266/2015-006-01 for Point Beach Nuclear Plant, Unit 1. NextEra Energy Point Beach, LLC is providing this revised LER regarding the Unit 1 automatic reactor trip.
This letter contains no new regulatory commitments.
If you have any questions please contact Mr. Bryan Woyak, Licensing Manager, at 920/755-7599.
Very truly yours, NextEra Energy Point Beach, LLC Eric McCartney Site Vice President Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014\\
, the NRC may not conduct or sponsor, and a person Is not required to respond to, the infonnation collection.
- 6. LERNUMER YEAR I SEQUENTIAL I NUMBER REV NO.
2015 -
006 01
- 3. PAGE 2
OF 2
At 1912 on November 28, 2015 with Unit 1 in MODE 1 at full power, an automatic reactor trip was actuated as the result of a failure of the Main Generator Automatic Voltage Regulator (AVR). All control rods fully inserted into the core. The Auxiliary Feedwater Pumps started as expected on low steam generator level. The Auxiliary Feedwater system was secured and decay heat removal was provided by the Condenser Steam Dumps utilizing the Main Feedwater system. All other safety systems functioned as designed.
The Unit 1 Main Generator AVR was repaired, returned to service and the unit returned to full power operations.
This 60-day licensee event report is being submitted in accordance with the requirements of 10 CFR 50. 73(a)(2)(iv)(A) for I the automatic actuation of the reactor protection system and auxiliary feedwater system.
Cause of the Event
The cause of the automatic reactor trip was due to the failure of an isolation transducer module in the Main Generator AVR.
Analysis of the Event
Troubleshooting activities completed as part of the post trip investigation identified a failed isolation transducer module within the main generator AVR. The main generator AVR isolation transducer module failure resulted in an indicated over excitation protection set point being exceeded causing a generator lockout. The generator lockout caused the turbine to trip. The reactor tripped as a result of the turbine trip.
Corrective Actions
The Unit 1 Main Generator AVR was repaired, returned to service and the unit returned to full power operations.
Safety Significance
The event was determined to be of very low safety significance. During the event and subsequent recovery actions, there was no loss of any safety systems, structures or components. All control rods fully inserted into the core as designed to control reactivity and temperature of the core. This event had no impact on the safety of the core. The Auxiliary Feedwater Pumps started as expected on low steam generator level. The Auxiliary Feedwater system was secured and decay heat removal was provided by the Condenser Steam Dumps utilizing the Main Feedwater system. There was no impact on the health and safety of the public as a result of this event.
Similar Events
There have not been similar events of automatic reactor trips in the past three years.
Component Failure Data
Main Generator Automatic Voltage Regulator DC-DC Isolation Transducer Module Style 1A96166G11 -Cutler-Hammer