Event Notification Report for April 25, 2006

UNANALYZED CONDITION - CONTROL LOGIC ERROR

"TMI Issue Report # 482679 identified an issue while performing reviews of fire abnormal operating procedures to assure compliance with the Fire Hazards Analysis Report (FHAR), in that a control logic error was identified in the circuitry elementary drawing for the isolation valves DH-V-6A and DH-V-6B between the Borated Water Storage Tank (BWST) and the Reactor Building (RB) sump. Plant circuitry was verified to be wired as per the elementary drawing. This circuitry design was to prevent a hot short, due to a fire, from opening the valve.

"However, the identified control logic error could allow a spurious opening to occur on DH-V-6A or DH-V-6B due to a fire. The FHAR credits these valves as being protected from spuriously opening due to a fire in AB-FZ-5 (Auxiliary Building 281' general area). If this protection is not provided, then spurious opening could result in draining the BWST inventory to the RB sump. This hot short condition would result in the depletion of the BWST inventory and loss of the High Pressure Injection (HPI) makeup capability, resulting in an unanalyzed condition that significantly degrades plant safety.

"This condition is reportable under 10 CFR 50.72(b)(3)(ii)(B), 'Any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.' A 60-day LER is also required under 10 CFR 50.73(a)(2)(ii)(B) for the same degraded condition.

"An hourly fire-watch has been established in the affected fire zone in the 281' elevation Auxiliary Building as an interim compensatory measure. Additionally, the control circuitry at the 1A and 1B ES MCCs will be modified to prevent the RB sump isolation valves DH-V-6A and DH-V-6B from spuriously opening due to a hot short."

The licensee notified the NRC Resident Inspector.

SERVICE WATER PIPING FLOODING CONCERN IMPACTS RHR

"At 0500 hours on April 25, 2006 with the plant in mode 5 and RCS loops filled, Operations declared the 21 and 22 Residual Heat Removal (RHR) pumps inoperable (see IP2-CR-2006-2133). This is reportable under 10 CFR 50.72(b)(3)(v)(B) as an event that at the time of discovery could have prevented the RHR pumps from removing residual heat. Residual heat removal is still available through the steam generators. The pumps were declared inoperable, but remained in operation, after a degraded horizontal section of Service Water (SW) line 405 was identified. SW line 405 is a non-ASME Section XI, non-Class A, seismically supported 24 inch return line routed through the Steam Generator Blowdown (SGBD) Tank room in the Plant Auxiliary Building (PAB) about 15 feet above the floor elevation of 51 feet. The ability of the pipe to withstand a seismic event has not currently been demonstrated. The consequence of a failure of this pipe is the flooding of the SGBD Tank room, cascading water down to the pipe case and then to the 15 foot PAB elevation. Water can drain to the transformer yard through a door at that elevation but the bottom of the RHR pump motors is lower than the door sill.

"Compensating actions have been implemented. These include provisions to open the door to the transformer yard with a security guard to monitor the open door, install sand bags at the entrance to the RHR pump room to prevent water entry, and install blocking devices to prevent backflow through the RHR pump room floor drains. A 24 hour watch is being provided for implementation of these compensatory measures. The watch will have a sump pump should it be necessary for leaks. The RHR pumps were declared operable at 1200 hours. Corrective action for SWS pipe 405 is being planned."

The licensee notified the NRC Resident Inspector.

* * * UPDATED ON 6/21/06 AT 0920 EDT BY B. ROKES TO J. ROTTON * * *

"Indian Point 2 is withdrawing the 8-hour non-emergency notification made on April 25, 2006, at 1231 hours. (Log No. 42524).

"The notification on April 25, 2006, reported an event or condition that could have prevented the Residual Heat Removal pumps from removing residual heat [10CFR54.72{b}(3)(v)(B)]. On April 25, 2006, at approximately 0500 hours, Operations declared the 21 and 22 Residual Heat Removal (RHR) pumps inoperable after a degraded horizontal section of Service Water (SW) line 405 was identified. SW line 405 is a non-ASME Section XI, non-Class A, seismically supported 24 inch return line routed through the Steam Generator Slowdown (SGBD) Tank room in the Plant Auxiliary Building (PAS) about 15 feet above the floor elevation of 51 feet. The ability of the degraded pipe to withstand a seismic event had not been demonstrated. The consequence of a failure of this pipe is the flooding of the SGBD Tank room, cascading water down to the 15 foot PAB elevation where the RHR pumps are located potentially flooding the RHR pump motors. Compensating actions were implemented and the RHR pumps declared operable at 1200 hours. Subsequently, a detailed engineering calculation was performed that included development of a finite element model of the piping using the SAP 2000 software package. The calculational methodology was based on ASME Section XI, Appendix H, Code Case N-513-1 and was augmented with stress intensity factor solutions from API-579. Stresses resulting from pressure, deadweight, and seismic loads were evaluated and found acceptable demonstrating that the overall structural integrity of the piping is maintained for all loading conditions. Based upon the observed pipe leak rate of approximately 15 gallons per hour (gph), an evaluation of the potential flaw size corresponding to this leak for the lower bound internal pressure was performed. It was concluded that the small stress contribution that would result from seismic loading would cause the flaw to have negligible propagation during a seismic event. Since it was determined that the pipe could support stable flaws much larger than the small flaw that corresponded to the observed leak rate, engineering concluded that the through wall flaws that produced the leakage did not threaten the structural integrity of the pipe. The estimated leakage that could have occurred from the pipe during a seismic event is bounded at 26 gph. Because the 26 gph leakage rate is well within the capacity of the two PAB sump pumps (50 gallons per minute each), there was never any threat to flooding the PAB or a challenge to the operability of the RHR pumps."

The licensee notified the NRC Resident Inspector and will be notifying the New York Public Service Commission.

Notified R1DO (M. Sykes).