05000282/LER-2009-007
| Prairie Island Nuclear Generating Plant | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 2822009007R01 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)
EVENT DESCRIPTION
Battery Rooms 11 and 12 are separated by an eight-inch concrete block wall that contains a penetration seal. The penetration seal contains two conduits (a five-inch conduit and a one-inch conduit) that are filled and sealed to form a fire barrier. On September 13, 2009, Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, documented the breach between the Prairie Island Nuclear Generating Plant (PINGP) 11 and 12 BatterylRooms.
The five-inch conduit was breached on September 3, 2009 to run temporary cable for maintenance between the two Battery Rooms. The conduit end caps and thermal insulating wool fill were removed. The temporary cable was run through the conduit which resulted in an unanalyzed fire barrier. On September 13, 2009, PINGP documented the breach between the 11 and 12 Battery Rooms.
An evaluation of the as-found configuration completed on October 28, 2009, determined that the as found configuration met the reportability requirement of 10 CFR 50.73(a)(2)(ii)(B).
EVENT ANALYSIS
The as-found configuration was a breached fire barrier, such that the required degree of separation for redundant safe shutdown trains was lacking, thus, this event is being reported in accordance with 10 CFR 50.73(a)(2)(ii)(B) as an unanalyzed condition that significantly degraded plant safety. The PINGP fire protection program requires compensatory measures be taken for missing or breached fire barriers (specifically, establish a fire patrol in the affected fire areas). A formal fire patrol was not established for the breached fire barrier. No actual loss of function occurred as a result of the as found condition, thus the condition was not a safety system functional failure.
SAFETY SIGNIFICANCE
The concrete block wall forms a fire barrier with a three-hour rating. Fire detection equipment on both sides of the fire barrier was operable during the breach. Should a fire have occurred on either side of the fire barrier, it would have been detected in its early stages by the fire detection equipment. This would have initiated a prompt response by the PINGP fire brigade. It is considered that fire detection and plant response along with the as-found barriers would have mitigated the potential adverse effects to the redundant equipment. There were no actual consequences to the health and safety of the public.
EIIS System Code: El FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)
CAUSE
The causal evaluation concluded that the site does not have a Fire Barrier Impairment Permit form so it was not included in the work package as required by fleet procedures. In addition, the pre maintenance walkdown failed to identify shortcomings in the planning process with respect to the temporary cable routing. Maintenance personnel should have "Stopped When Unsure" when the appropriate detail was not included in the work package.
CORRECTIVE ACTION
Upon discovery, NSPM initiated hourly fire watches to patrol the five-inch fire penetration seal until the maintenance work was complete.
This issue was discussed with General Supervisor Electrical Maintenance, Planning Manager, and Assistant Operations Manager with the expectation that responsibilities with respect to breaching fire penetrations be discussed with their departments.
Corrective Actions identified by the causal evaluation include:
- Creating a Fire Barrier Impairment Permit to be utilized when preparing work packages that require breaching a fire barrier.
- Planning Supervision will discuss planner responsibilities to include the Fire Barrier Impairment Permit in work packages that require breaching a fire barrier.
- Electrical Maintenance Supervision will discuss with maintenance personnel the following:
o The requirements to utilize the Fire Barrier Impairment Permit in work packages that affect fire barrier penetrations.
o Notifying Operations of the need for compensatory measures for fire barrier impairments.
- Revise maintenance procedures to include procedural guidance that addresses temporary cabling which is routed through multiple fire areas.
PREVIOUS SIMILAR EVENTS
A review of Licensee Event Reports for PINGP since 2004 found one similar event where a fire barrier was found to have been breached without compensatory measures. The event was documented in LER 1-07-03 (Unanalyzed Condition due to Breached Fire Barrier).