05000373/LER-2004-002, Re B Control Room Area Filtration Subsystem Inoperable Due to Unsecured Inspection Port Cover
| ML043370123 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/24/2004 |
| From: | Landahl S Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 04-002-00 | |
| Download: ML043370123 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3732004002R00 - NRC Website | |
text
Or ExekenSM Exelon Generation Company, LLC LaSalle County Station 2601 North 21"Road Marseilles, IL 61341-9757 www.exeloncorp.com Nuclear November 24, 2004 10 CFR 50.73 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 LaSalle County Station, Units 1 and 2 Facility Operating License No. NPF-11 and 18 NRC Docket No. 50-373 and 50-374
Subject:
Licensee Event Report In accordance with 10 CFR 50.73 (a)(2)(i)(B), Exelon Generation Company, (EGC), LLC, is submitting Licensee Event Report Number 04-002-00, Docket No. 050-373.
Should you have any questions concerning this letter, please contact Mr. Terrence W. Simpkin, Regulatory Assurance Manager, at (815) 415-2800.
Respectfully, Susan Landahl Plant Manager LaSalle County Station
Attachment:
Licensee Event Report cc:
Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - LaSalle County Station J222--
Abstract
On 9/29/04, during the performance of a surveillance, it was discovered that the 'B' control room area filtration (CRAF) subsystem was unable to maintain a positive pressure in the Auxiliary Electric Equipment Room of greater than or equal to 0.125 inches water gauge relative to adjacent areas during the pressurization mode of operation at a flow of less than or equal to 4000 CFM, as required by Technical Specification Surveillance Requirement 3.7.4.5.
Troubleshooting identified an unsecured inspection port cover in the suction ductwork associated with fire damper OVE39Y.
The cover was reinstalled and the surveillance was completed acceptably.
A root cause investigation was unable to determine the reason for the unsecured cover.
Corrective actions included taping the associated inspection port cover latches, and procedural changes to ensure configuration management and material condition of the inspection access port doors.
NRC FORM 366 (6-2004)
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)
The direct cause of this event was improperly secured latches on the inspection port cover. A root cause investigation was unable to identify the root cause of the latches being improperly secured.
The most probable root cause was that the latch on the access door for the OVE39Y fire damper was bumped while a mechanic was climbing on the ductwork to inspect the OVE40Y fire damper during the surveillance of LMS-FP-22, "Fire Damper Visual Inspection," on 02/25/04.
Due to the inadequately secured inspection port cover, the vibration and air flow of the system could have forced the cover off during swaps of 'A' and 'B' CRAF subsystems.
D.
SAFETY ANALYSIS
The safety significance of this event was minimal.
While the AEER did not meet the greater than or equal to 0.125 inch water gauge TS SR requirement, the AEER maintained positive differential pressure with respect to all adjacent spaces during the event.
LTS-400-17 was performed on the 'A' CRAF subsystem just prior to identifying the problem with the 'B' subsystem, and it was determined to be fully operable.
The control room envelope was always maintained within its design requirements.
E.
CORRECTIVE ACTIONS
- 1.
Safety-related tape was installed over the cover for the inspection port found open on OVE39Y (Complete).
- 2.
Surveillance procedure LMS-FP-22, "Fire Damper Visual Inspection," will be revised to include a sign off for configuration management and material condition of inspection port cover latches (AT# 258287-13).
F.
PREVIOUS OCCURRENCES
A review of Licensee Event Reports for the past 10 years identified no previous occurrences of events caused by unsecured ductwork covers.
G.
COMPONENT FAILURE DATA
No components failed during this event.