05000237/LER-2003-002, High Pressure Coolant Injection Room Cooler Bearing Degradation
| ML032580458 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/08/2003 |
| From: | Hovey R Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RHLTR: #03-0061 LER 03-002-00 | |
| Download: ML032580458 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2372003002R00 - NRC Website | |
text
9-Exek5nlsm Exelon Generation www.exeloncorp.com Nuclear Dresden Generating Station 6500 North Dresden Road Morris, IL 60450-9765 Tel 815-942-2920 10 CFR 50.73 September 08, 2003 RHLTR: #03-0061 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 Facility Operating License No. DRP-19 NRC Docket No.50-237
Subject:
Licensee Event Report 2003-002-00, High Pressure Coolant Injection Room Cooler Bearing Degradation" Enclosed is Licensee Event Report 2003-002-00 "High Pressure Coolant Injection Room Cooler Bearing Degradation," for the Dresden Nuclear Power Station Unit 2. This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D), Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident."
Should you have any questions concerning this report, please contact Jeff Hansen, Regulatory Assurance Manager at (815) 416-2800.
Respectfully, M
R. J. Hovey Site Vice President Dresden Nuclear Power Station Enclosure cc:
Regional Administrator - NRC Region l NRC Senior Resident Inspector - Dresden Nuclear Power Station
I C-FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OBM NO. 3150-0104 EXP 7-31-2004 (7-2001)
COMMISSION
, 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)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION Dresden Nuclear Power Station Unit 2 05000237 NUMBER NUMBER 2003 002 00 2 of 3 (If more space Is required, use additional copies of NRC Form 366A)(17)
A.
Plant Conditions Prior to Event:
Unit: 02 Event Date: 07-10-2003 Event Time: 1645 CDT Reactor Mode: 1 Mode Name: Run Power Level: 100 percent Reactor Coolant System Pressure: 1000 psig B.
Description of Event
This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident."
On July 10, 2003, Operations personnel observed excessive noise and vibration from the Unit 2 High Pressure Coolant Injection (HPCI) room cooler. The room cooler was secured, restarted later for troubleshooting, secured again and taken out of service. On July 11, 2003, personnel replaced the inboard and outboard fan shaft bearings and the system was declared operable. The rotating equipment component engineer examined the removed bearings. The outboard bearing was found to be in good condition. However, the inboard bearing, though still round, was severely worn and pitted on the entire surface of each ball, indicating inadequate lubrication.
C.
Cause of Event
The root cause for the event was that the lubrication frequency for the HPCI room cooler was incorrectly changed in 1996 from quarterly to every two years, which resulted in inadequate bearing lubrication. Quarterly lubrication of the bearings would have prevented this condition from developing. Additionally, the root cause determined that at the time the frequency was changed, there were inadequate controls in place to prevent this event from occurring.
(NRC Cause Code E)
An extent of condition review was performed and determined that during the last two years there have been major revisions to the Performance Centered Maintenance (PCM) templates, including relays, turbine generators, emergency diesel generators, heating, ventilation and air conditioning, air operated valves, pumps, compressors, motor operated valves, and switchyard components. There were two areas that were considered to be applicable to the extent of condition for this issue. These areas were in oil and grease applications. The oil change and sampling program underwent a one hundred percent review in the second half of 2001 and early 2002. This effort rebaselined the oil program system by system, consistent with post-extended power uprate operation. This effort has not been applied to the grease preventative maintenance tasks. Although this level of review has not been performed specifically from a grease perspective, there have only been two grease related issues during the last two years. The two grease related issues were this issue and an issue with a misinterpreted preventative maintenance (PM) change request, which also originated from a 1994 vintage PM change.
A V4IRC FORM 366A U.S. NUCLEAR REGULATORY APPROVEDBYOMBNO.31500104 COMMISSION EXPIRES 0713112004 (7-2001)
, 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)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION Dresden Nuclear Power Station Unit 2 05000237 NUMBER NUMBER 2003 002 00 3 of 3 (If more space is required, use additional copies of NRC Form 366A)(17)
D.
Safety Analysis
The main function of the HPCI System is to provide make up coolant to the reactor in the event of a small-break loss of coolant accident. An inoperable HPCI room cooler fan would not have prevented the HPCI System from initiating and injecting to the reactor. Continued operation of the HPCI System under these conditions would result in a room temperature for which the equipment in the HPCI room is not designed to withstand. The potential for early loss of HPCI as a consequence of loss of the room cooler has been investigated. While room cooler mixing is necessary to support extended operation of the HPCI system, the HPCI turbine would operate for considerable time without the fan.
Had the HPCI System become unable to operate due to elevated room temperatures, the Isolation Condenser, Automatic Depressurization System, and Low Pressure Emergency Core Cooling Systems, (Low Pressure Coolant Injection, Core Spray) were available to provide reactor pressure and inventory control during any postulated Design Basis Accident. Therefore, the consequences of this event were minimal and the event had minimal impact on the health and safety of the public and reactor safety.
E.
Corrective Actions
The Unit 2 HPCI room cooler fan shaft bearings were replaced.
The Unit 3 HPCI room cooler was observed to verify that no abnormal condition associated with the room cooler was present and the Unit 3 HPCI bearings were greased.
The frequency of the bearing lubrication for the Unit 2 and Unit 3 HPCI room coolers was changed to quarterly from every two years.
The Component Maintenance Organization will review grease preventative maintenance items for critical components.
The preventative maintenance program has undergone extensive revision since the event resulting in a robust program requiring a multi-discipline review of all revisions prior to implementation. This program incorporates industry experience, vendor information, OPEX, and plant specific application of a system or component.
F.
Previous Occurrences
None G.
Component Failure Data
N/A