05000461/LER-2004-001, Generator Neutral Over-Voltage / Lockout Leads to Reactor Scram
| ML041540438 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 05/21/2004 |
| From: | Bement R AmerGen Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-603673 LER 04-001-00 | |
| Download: ML041540438 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| 4612004001R00 - NRC Website | |
text
Amerfeta An Exelon Company Clinton Power Station R. R.3, Box 228 Clinton, IL 61727 10 CFR 50.73 U-603673 May 21, 2004 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Licensee Event Report 2004-001 -00 Enclosed is Licensee Event Report (LER) No. 2004-001-00: Generator Over-Voltage /
Lockout Leads to Reactor Scram. This report is being submitted in accordance with the requirements of 10CFR50.73.
Should you have any questions concerning this report, please contact Mr. William Iliff, Regulatory Assurance Manager, at (217)-937-2800.
Respectfully, R. emnt Site Vice President Clinton Power Station RSF/blf
Enclosure:
Licensee Event Report 2004-001-00 cc:
Regional Administrator - NRC Region Ill NRC Senior Resident Inspector-Clinton Power Station Office of Nuclear Facility Safety - IEMA Division of Nuclear Safety
- - G NRC ORM 66
.S. UCLER RGULAORY APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004
Abstract
On March 22, 2004, at about 1931 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.347455e-4 months <br />, an automatic reactor scram occurred with the plant at 93 percent power. Operators received a trouble alarm in the Main Control Room for the Hydrogen and Stator Cooling Cabinet followed by a Main Generator neutral over-voltage trip and Generator Trip System 2 Lockout. The Generator trip caused a Main Turbine trip and Turbine Control Valve fast closure, resulting in an automatic reactor scram. All control rods fully inserted. Following the reactor scram, reactor water level dropped, as expected, to the Low Level 3 trip setpoint, initiating the Reactor Protection System. Operators entered.
Emergency Operating Procedures due to the low reactor water level transient. The root cause for the reactor scram is still under investigation and components within the 'B' Isolated Phase Bus Duct Cooling System are a focus of the investigation. Corrective action to date for this event include inspecting all 3 Isolated Phase Bus Ducts for degradation, removing the Partial Discharge Analysis System cables from all 3 Isolated Phase Bus Ducts, and repairing an expansion link on a conductor in the 'B' Isolated Phase Bus Duct.
NRC FORM 366 (7-2001)
(If more space Is required, use additional copies of (If more space Is required, use additional copies of NRC Form 366A) (17)
CAUSE OF THE EVENT
A complex troubleshooting plan was initiated to investigate this event. The cause of the Generator neutral over-voltage trip / lockout that resulted in a reactor scram is still under investigation and components within the 'B' Isolated Phase Bus Duct Cooling System [BDUC]
[EL] are a focus of the investigation. During the troubleshooting a severed Partial Discharge Analysis (PDA) System cable [CBL] and a torn conductor expansion link were both discovered in the 'B' Isolated Phase Bus Duct.
The root cause determination for this event will be provided in a supplement to this report. The expected submittal date for the supplemental report is July 30, 2004.
SAFETY ANALYSIS
There were no actual safety consequences associated with his event. The event was reviewed for analyzed transients discussed in Chapter 15 of the Clinton Power Station Updated Safety Analysis Report. The analysis determined that this event was within the design basis of the plant.
No safety system functional failures occurred during this event.
CORRECTIVE ACTIONS
Corrective actions will be established following determination of the cause of this event and will be provided in a supplement to this report. All three Isolated Phase Bus Ducts have been inspected for degradation, the Partial Discharge Analysis System cables have been removed from all three Isolated Phase Bus Ducts, and an expansion link on the conductor in the 'B' Isolated Phase Bus Duct has been repaired.
PREVIOUS OCCURRENCES
A review for previous events will be completed following the cause determination and the results of the review will be provided in the supplement to this report. Based on current information, no previous similar events are known.
COMPONENT FAILURE DATA
Component failure data will be provided in the supplemental report for this event.
NHU FORHM 366bA tl-z001)