05000282/LER-2007-003
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2822007003R01 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 07 03
EVENT DESCRIPTION
On August 9, 2007, Nuclear Management Company, LLC (NMC) staff documented an apparent breach between the Prairie Island Nuclear Generating Plant (PINGP) Train A and Train B auxiliary feedwater1 pump rooms. The floor trench in the rooms is separated by a 12-inch thick concrete barrier. One of the penetrations in the barrier was a 4-inch pipe sleeve through which a 3-inch rubber hose has been run for several years. An evaluation of the as-found configuration determined on August 24, 2007, that the as-found configuration could have adversely affected the ability to safely shutdown in the event of a fire.
EVENT ANALYSIS
The as-found configuration was a breached fire barrier, such that the required degree of separation for redundant safe shutdown train was lacking, thus, this event is being reported in accordance with 10 CFR 50.73(a)(2)(ii) as an unanalyzed condition.
Impact on Safety System Functional Failure Performance Indicator No actual loss of function occurred as a result of the as-found condition. Consequently, this event is not reportable per 10CFR 50.73(a)(2)(v).
SAFETY SIGNIFICANCE
This event did not result in a loss of function. In the event of a fire, it is possible that flammable liquids could have passed between rooms in the space between the hose and the pipe sleeve. 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 had been established in the affected fire areas for other issues; of the several years the as-found configuration was in place, the only periods during which a formal fire patrol did not exist was from September 19, 2005, to December 12, 2005 and from December 22, 2005, to April 7, 2006 (with a brief exception during maintenance on January 18, 2006). Even though no formal fire patrol existed during the identified periods, a review of card reader logs indicates the fewest times the room was accessed on any day during this period was 15 times, which increases the likelihood any fire would have been detected prior to affecting redundant trains. Thus, this event did not affect the health and safety of the public and the safety significance of this event is considered minimal.
1 EIIS System Identifier: BA FACILITY NAME (1) � DOCKET NUMBER (2) LER NUMBER (6� PAGE (3) 07 -- 03 --
CAUSE
The root cause evaluation concluded there were two root causes for the condition: (1) requirements for use of the AFWP room trench and trench fire barrier pipe sleeve are not procedurally controlled, and (2) insufficient procedural direction, guidance, or criteria for evaluators to help them determine an appropriate threshold for issuing a new action request as a consequence of their evaluation findings.
CORRECTIVE ACTION
The hose was removed and the fire barrier was restored (filled with fire-retardant wool and capped with threaded caps).
Corrective Actions identified by the root cause evaluation include procedure changes to:
- prohibit the use of a hose in the AFWP room trench without an evaluation or temporary modification, and
- add guidance for criteria on when a new corrective action process action request is warranted during an apparent cause evaluation or condition evaluation.
PREVIOUS SIMILAR EVENTS
Review of Licensee Event Reports for Unit 1 and Unit 2 since 2004 found no previous similar events where a fire barrier was found to have been breached without compensatory measures.