05000373/LER-2004-002
| Event date: | 09-29-2004 |
|---|---|
| Report date: | 2-4-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3732004002R00 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
- General Electric - Boiling Water Reactor, 3489 Megawatts Thermal Rated Core Power
A. CONDITION PRIOR TO EVENT
� Event Time: 2105 Unit(s): 1/2 Event Date: 09/29/04� � Reactor Mode(s): 1/1 Power Level(s): 100/100 Mode(s) Name: Run/Run
B. DESCRIPTION OF EVENT
On 9/29/04, during the performance of surveillance LTS-400-17, "Control Room and Auxiliary Electric Equipment Room HVAC Isolation Damper Surveillance, Smoke and Radiation Detection," it was discovered that the 'B' control room area filtration (CRAF) subsystem was unable to maintain adequate positive pressure in the Auxiliary Electric Equipment Room (AEER). Technical Specification (TS) Surveillance Requirement (SR) 3.7.4.5. requires that each CRAF subsystem maintain 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.
The LTS-400-17 test results for 'B' train pressurization indicated the AEER did not have a positive pressure of greater than or equal to 0.125 inches water gauge with respect to the following four areas:
- U2 cable room in U2 switchgear
- U2 Div 2 switchgear room
- Ul Cable spreading room
- U2 Cable spreading room The 'B' CRAF subsystem was declared inoperable at 2105 hours0.0244 days <br />0.585 hours <br />0.00348 weeks <br />8.009525e-4 months <br /> on 9/29/04, and TS 3.7.4 Required Action (RA) A.1 was entered to restore the CRAF subsystem to operable status within 7 days.
On 9/30/04, at 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br />, an 8 inch x 8 inch inspection port was found open
- in the suction ductwork associated with fire damper OVE39Y. The cover was lying on top of ductwork next to the access port opening. When it was reinstalled, the Unit 2 AEER ventilation (VE)[VI] differential pressure increased by 0.21 inches water gauge.
Surveillance LTS-400-17 was re-performed satisfactorily. On 10/1/04, at 0418 hours0.00484 days <br />0.116 hours <br />6.911376e-4 weeks <br />1.59049e-4 months <br />, the 'B' CRAP subsystem was declared operable, and TS RA 3.7.4.A.1 was exited.
Because it is probable that the inspection port cover was missing and the 'B' subsystem could not meet its surveillance requirement during periods that the 'A' subsystem has been inoperable, this event is reportable under 10CFR50.73(a)(2)(i)(B) as a condition prohibited by the plant's Technical Specifications.
C. CAUSE OF EVENT
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 Dampei 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.C 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.
CORRECTIVE ACTIONS E.
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.C PREVIOUS OCCURRENCES A review of Licensee Event Reports for the past 10 years identified no previous occurrences of events caused by unsecured ductwork covers.
COMPONENT FAILURE DATA G.
No components failed during this event.