05000237/LER-2004-005, Regarding Plants Inoperable Turbine Condenser Vacuum - Low Switches
| ML042530097 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 08/30/2004 |
| From: | Bost D Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR: #04-0058 LER 04-005-00 | |
| Download: ML042530097 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2372004005R00 - NRC Website | |
text
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Exelon Generation Company, LLC www.exeloncorp.com ExeI 1
Dresden Nuclear Power Station Nuclear 6500 North Dresden Road Morris, IL 60450-9765 10 CFR 50.73 August 30, 2004 SVPLTR: #04-0058 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Facility Operating License Nos. DRP-19 and DRP-25 NRC Docket Nos. 50-237 and 50-249
Subject:
Licensee Event Report 2004-005-00, "Units 2 and 3 Inoperable Turbine
- Condenser Vacuum - Low Switches" Enclosed is Licensee Event Report 2004-005-00, "Units 2 and 3 Inoperable Turbine Condenser Vacuum - Low Switches," for Dresden Nuclear Power Station. This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), 'Any operation or condition which was prohibited by the plant's Technical Specifications."
Should you have any questions concerning this report, please contact Jeff Hansen, Regulatory Assurance Manager, at (815) 416-2800.
Respectfully, Danny G. Bost Site Vice President Dresden Nuclear Power Station Enclosure cc:
Regional Administrator - NRC Region III NRC Senior Resident Inspector - Dresden Nuclear Power Station C
z,
Abstract
On May 16, 2004, with Unit 2 at approximately 100 percent power in Mode 1, the 2A Turbine Condenser Vacuum - Low switch for the Reactor Protection System became inoperable due to the collection of water In its vacuum sensing line. The inoperable switch was not immediately detected and the condition existed for a period of time that exceeded the Completion Times associated with Required Actions of Technical Specification 3.3.1.1, *Reactor Protection System (RPS)
Instrumentation.
The root cause of the event was that previous efforts to correct the vacuum sensing line errors were too narrowly focused and did not inspectfrepair all internal and external sensing lines to all turbine hoods. Temporary vent valves have been installed on Turbine Condenser Vacuum - Low switches 2A, 2C, 3A and 3C to continuously purge and clear condensation from the line. The corrective action to prevent recurrence is to perform internal and external condenser walk downs to determine Turbine Condenser Vacuum - Low switch sensing line slope and repair or modify as necessary.
(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 Form 366A)
F.
Previous Occurrences
A review of Dresden Nuclear Power Station Licensee Event Reports (LERs) and operating experience over the previous six years identified the following similar occurrence associated with a failed Turbine Condenser Vacuum -
Low switch.
LER 98-006-00, "RPS Condenser Vacuum Switch Potentially Inoperable Due To Improper Instrument Sensing Line Slope," dated July 15, 1998. The LER discussed an event in which a Turbine Condenser Vacuum - Low switch was determined to be inoperable due to water collecting in the sensing line. The corrective action to correct the slope of the 3C Turbine Condenser Vacuum - Low switch sensing line was not successful in preventing this event.
G.
Component Failure Data
N.A.