05000413/LER-2003-001, From Catawba, Unit 1 Regarding High Steam Generator Level Turbine Trip Causes Reactor Trip & Automatic Start of Motor Driven Auxiliary Feedwater System Pumps
| ML030920019 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/24/2003 |
| From: | Gordon Peterson Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 03-001-00 | |
| Download: ML030920019 (10) | |
| Event date: | |
|---|---|
| Report date: | |
| 4132003001R00 - NRC Website | |
text
11 /I rr
-.11 Duke
- rPower A D"k E-m COp-Gary R. Peterson Vice President Duke Power Catawba Nuclear Station 4800 Concord Road York, SC 29745 (803) 831-4251 OFFICE (803) 831-3221 FAX March 24, 2003 U.S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555
Subject:
Catawba Nuclear Station, Unit 1 Docket No. 50-413 Licensee Event Report 413/03-001 Attached is Licensee Event Report 413/03-001 titled "High Steam Generator Level Turbine Trip Causes Reactor Trip and Automatic Start of Motor Driven Auxiliary Feedwater System Pumps."
There are no regulatory commitments contained in this letter or its attachment.
This event is considered to be of no significance with respect to the health and safety of the public.
If there are any questions on this report, please contact L.J. Rudy at (803) 831-3084.
Attachment T 6 0-1
?
Document Control Desk Page 2 March 24, 2003 xc (with attachment):
Mr. Luis A. Reyes Regional Administrator, Region II U.S. Nuclear Regulatory Commission 61 Forsyth Street, S.W., Suite 23T85 Atlanta, GA 30303 Mr. Robert E. Martin (addressee only)
U.S. Nuclear Regulatory Commission Mail Stop 08-H12 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Eugene F. Guthrie NRC Senior Resident Inspector Catawba Nuclear Station INPO Records Center 700 Galleria Place Atlanta, GA 30339-5957 Marsh & McLennan, Inc.
Mr. Kenneth W. Gannaway 100 N. Tryon Street Charlotte, NC 28202
I I I
Abstract
'On February 4, 2003, at 1005 hours0.0116 days <br />0.279 hours <br />0.00166 weeks <br />3.824025e-4 months <br />, Catawba Unit 1 tripped from 100%
power.
A Main Feedwater (MFW) System header pressure transmitter was being returned to service following replacement.
As the transmitter was valved in, its hydraulic interaction with the other two nearby transmitters caused MFW header pressure indication to the MFW control system to fluctuate.
In response to the transient, the MFW control system switched from automatic to manual control, as designed, at a pre-determined pressure difference between the transmitters.
As control room operators attempted to control steam generator levels manually, a high-high level on steam generator B resulted in a turbine trip, which resulted in a reactor trip.
The high-high level also resulted in a trip of the MFW pumps, which caused an automatic start of the motor driven Auxiliary Feedwater (AFW) System pumps.
This event was caused by an inadequate understanding of the MFW control system response to a common impulse line hydraulic interaction.
Corrective actions planned in response to this event include training appropriate plant personnel concerning MFW control system design and response and revising procedures associated with the calibration and maintenance of selected transmitters.
NRC FORM 366 (7-2001)
2r (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Forn 366A) (17)
- Actual moderator temperature coefficient value at the time of the trip.
- Actual plant configuration and maintenance activities at the time of the trip.
- Credit for recent Nuclear Service Water to AFW System modifications to minimize clam intrusion.
The conditional core damage probability for this event is 2.OE-07, which is less than the accident sequence precursor threshold of 1.OE-06.
The dominant core damage sequences associated with this event have
,the significant containment safeguards systems available.
These
?include the containment spray and hydrogen mitigation systems.-
Furthermore, most have low to moderate reactor coolant system pressures at reactor vessel failure.
Sequences of this nature contribute insignificantly to the Large Early Release Frequency (LERF), which is dominated by the interfacing systems loss of coolant accidents and seismic initiating events.
Therefore, this event is judged to have no significance with respect to the LERF for Catawba.
While this event resulted in an automatic isolation of MFW, post-trip MFW flow could have been reestablished by the control room operators if desired.
Therefore, this event did not meet the initiating event criterion for a reactor trip with loss of the normal heat sink.
This event was of no significance with respect to the health and safety of the public.
ADDITIONAL INFORMATION
Within the last three years, four other reactor trip events occurred from power operation at Catawba as follows:
LER 413/00-001 described a Unit 1 reactor trip due to actuation of the turbine trip instrumentation inputs to the Solid State Protection System logic.
This resulted from an electrical short within an electrical connector on the normally energized turbine (if more space is required, use additional copies of NRC Form 366A) (17) electrical trip solenoid valve.
The root cause of the event was a misapplication of the connector insert insulating material.
LER 414/00-003 described a Unit 2 reactor trip following a MFW transient caused by rainwater entering the turbine building and affecting control of one of the MFW pumps.
The root cause of this event was determined to be inadequate oversight of a turbine building roof modification.
LER 413/01-001 described a Unit 1 reactor trip caused by a turbine trip.
The root cause of this event was determined to be incomplete troubleshooting analysis associated with the main turbine protection system mechanical trip solenoid valve.
LER 414/01-003 described a Unit 2 reactor trip resulting from low reactor coolant flow when the 2D reactor coolant p~ump 6900 VAC feeder breaker opened in response to protective relay actuation caused by an electrical fault internal to the pump, motor.
The corrective actions taken in response to these events would not have prevented this latest event from occurring.
Therefore, this event was determined to be non-recurring in nature.
Energy Industry Identification System (EIIS) codes are identified in the text as [EIIS: XX].
This event is not considered reportable to the Equipment Performance and Information Exchange (EPIX) program.
This event did not involve a Safety System Functional Failure.
There were no releases of radioactive materials, radiation exposures, or personnel injuries associated with this event.