05000263/LER-2003-001, Degraded Fire Barrier Penetration Discovered During Walkdown
| ML031400643 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 05/09/2003 |
| From: | Denise Wilson Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-03-029 LER 03-001-00 | |
| Download: ML031400643 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 2632003001R00 - NRC Website | |
text
N 1iA Monticello Nuclear Generating Plant Committed to NucIearExcetl' Operated by Nuclear Management Company, LLC May 09, 2003 L-MT-03-029 10 CFR Part 50 Section 50.73 US Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 LER 2003-001 Degraded Fire Barrier Penetration Discovered during a Walkdown A Licensee Event Report for this occurrence is attached. This report contains no new NRC commitments.
Contact Ron Baumer at (763) 295-1357 if you require further information.
David L. Wilson Site Vice President Monticello Nuclear Generating Plant Enclosure c:
Regional Administrator - IlIl NRC NRR Project Manager, NRC Sr. Resident Inspector, NRC Minnesota Department of Commerce 2807 West County Road 75
- Monticello, Minnesota 55362-9637 Telephone: 763-295-5151
- Fax: 763-295-1454 bt.
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Abstract
On March 13, 2003 during a walkdown of fire barrier penetration FZ-4900 in the upper 4KV room it was discovered that a portion of a penetration seal was degraded allowing the upper and lower 4KV rooms to communicate with each other. The barrier was declared inoperable and a continuous fire watch was established. In accordance with 10 CFR 50.72(b)(3)(ii), an 8-hour event notification was made. The Updated Fire Hazards Analysis was reviewed to identify other locations where gypsum board assemblies are used as penetrations. No other penetrations were found to be inoperable as a result of this walk-down. On March 15, 2003 the barrier was repaired and declared operable.
NRC FORM 366 (7-2001) i (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)
Several possible causes including improper construction were considered during the investigation of the
%" x 4" breach.
- 1. Turbine Building vibration, which over time may have shaken loose the joint compound material, exposing the hole.
- 2. It may be possible that incidental maintenance work around the duct could have loosened the sealant and created the hole. For example, bus duct inspections may have resulted in movement of the back of the duct creating the hole.
- 3. This penetration was modified in the early 1980s, making it approximately 20 years old indicating possible age-related degradation. This failure mode was considered, but determined to be unlikely due to previous penetration inspections.
The most likely cause of the breach developing was due to the improper construction of the penetration along with some contribution of items 1, 2, and 3 above. The actual cause of the breach developing in penetration FZ4900 is indeterminate.
Corrective Action
The station performed repairs to penetration FZ-4900 under Work Order 0307578, which restored operability.
Investigation of the extent of condition with respect to the installation non-conformances continues to be evaluated under our corrective action program.
Failed Component Identification There was no failed component for this event.
Previous Similar Event No previous events were found similar to the event in LER 2003-001. However, a review of previous station events found the following events related to degraded fire barriers:
LER 263-50/87011, "Fire Barrier Penetration Found Inoperable due to Inadequate Procedure" LER 263-50/88004, "Fire Barrier Found Inoperable in Turbine Building due to Inadequate Procedures" LER 263-50/89001, Discovery of Fire Barrier Penetration Inoperable due to Error in Identification of Required Fire Barriers" LER 263-50/89013, Fire Barrier Penetration Inoperability as a Result of Failure to Adequately Assess Original Seal Configuration" LER 263-50/90009, Inoperable Fire Barrier Penetration Seal due to Non-compliance with Approved Plant Procedures" (If more space is required, use additional copies of NRC Form 366A) (17)
LER 263-50/91021, "Inoperable Fire Penetration due to Pipe Movement Resulting from Possible Water Hammer" LER 263-50/94007, Surveillances Failed to Identify an Unsealed Fire Barrier'