Event Notification Report for August 24, 2007

FIRE BARRIER SEPARATION CRITERIA NOT MET FOR AFWP ROOMS

"On August. 24, 2007, Prairie Island staff completed a past operability evaluation of a condition involving a missing fire barrier, such that the required degree of separation for redundant safe shutdown trains was lacking. The floor trench which transverses the auxiliary feedwater pump (AFWP) rooms has a 12 inch thick concrete barrier at the interface of Fire Areas 31 and 32 (Unit 1 and Unit 2 AFWP rooms). That barrier is required by NRC commitment to prevent the flow of flammable liquid (i.e., oil) and fire suppression water from transferring fire from one AFWP room to the other. That barrier contains penetrations which shall be controlled like any other fire barrier penetration.

"One of those penetrations is a 4 inch pipe sleeve. When stuffed with fire-retardant wool and capped with provided threaded caps, it is a qualified seal. However, for approximately ten years, the 4 inch sleeve has contained a 3 inch hose. During most of this 10 year period there were hourly fire watches in these two fire areas, which were an acceptable compensatory measure. However; for a period between Sept. 19, 2005 and April 9, 2006 there were no hourly fire watches in place. Prairie Island staff concluded the required degree of separation was lacking with no compensatory measures, thus the as-found condition is reportable per 10 CFR 50.72(b)(3)(ii) as an unanalyzed condition that significantly degraded plant safety."

This condition was discovered and corrected on 8/10/07.

The licensee notified the NRC Resident Inspector.

REACTOR TRIP BREAKER UNDERVOLTAGE TRIP FAILURE DURING SURVEILLANCE TESTING

"During routine surveillance testing on Unit 1 'B' Train Solid State Protection System, per FNP-1-STP-33.2B, the 'B' Train Rx Trip Breaker Failed to trip when a trip signal was sent from one of the manual function test push buttons. Indicated voltage did go to zero, but the Reactor Trip Breaker did not open. Per the testing sequence, the shunt trip for this breaker was being blocked at this time. A timeout was taken to determine the best course of action. Following discussions with Shift Manager, Duty manager, Emergency Director, and Electrical Maintenance supervision, it was decided to determine if the breaker would trip via the shunt trip mechanism. The surveillance testing was continued, and the 'B' Reactor Trip Breaker opened when the test signal was again inserted with the shunt trip unblocked. The 'B' Reactor Trip Breaker was replaced with a new breaker, and was subsequently tested sat per applicable sections of the surveillance test procedure.

"***This event did not result an any offsite radiation release, and did not pose a threat to the general public.***"

The licensee informed the NRC Resident Inspector.

PARTIAL LOSS OF PROCESS COMPUTER PARAMETERS TO ERDS

"A portion of the Palisades Plant Process Computer (PPC) including a significant number or Emergency Response Data System (ERDS) trended input became inoperable due to a host computer failure. The cause of the host computer failure is unknown.

"Necessary redundant control room parameters exist and are functioning. Palisades is currently in no associated Technical Specification LCOs.

"Repair of the host computer will be prudently pursued. NRC notification of repair completion will occur."

The licensee notified the NRC Resident Inspector.

* * * UPDATE AT 2005 ON 8/26/07 FROM MULFORD TO SNYDER * * *

The licensee restored the host computer at 1757 on 8/26/07 so it is now providing accurate data.

The licensee notified the NRC Resident Inspector. Notified R3DO (Lara).