05000266/LER-2005-002

LER-2005-002,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition
2662005002R00 - NRC Website

FACILITY NAME (1_1 DOCKET NUMBER (2) I YEAR I SEQUENTIAL REVISION LER NUMBER (6 PAGE (3)

Event Description:

On April 8, 2005, NMC staff identified a potential deficiency in the Point Beach Appendix R Safe Shutdown Charging Pumps' for a fire in Fire Area A06, 1B32 motor control center (MCC2) area.

• A review of the control cables' associated with charging pump 1P-2C indicated that cables were located within Fire Area A06. If a fire occurred in this area and damaged the control cables, the ability to start the pump from the control room would be lost.

• Fire Organization Plan, FOP 1.2 (Revision 6) for fire area A06 stated the strategy that should be used if reactor coolant pump4 (RCP) seal injection flow is lost for 10 minutes. Specifically, it states to ensure seal injection remains isolated. This is in conflict with the Safe Shutdown Analysis, which states that RCP seal cooling must be restored in a timely manner. If a prolonged loss of seal cooling occurs, the RCP seals could fail, resulted in leakage in excess of makeup capability.

charging pump capability and coolant pump seal cooling.

On April 28, 2005, a similar issue was documented for the Unit 2 charging pumps. Specifically, neither FOP 1.2, nor the Safe Shutdown Analysis Compliance Strategies, provided adequate guidance for manual actions necessary to restart these pumps to ensure adequate RCP seal cooling is established.

FOP 1.2 was revised on May 9, 2005 to revision 8, to ensure adequate manual actions are in place to maintain and establish Unit 2 charging pump capability and reactor coolant pump seal cooling.

On June 7, 2005, a continuing review of further information related to this condition, determined that the available charging pump capability was affected. The system would not provide sufficient reactor coolant pump seal cooling, thereby degrading the level of plant safety.

Event Analysis:

Unit 1:

The Safe Shutdown Analysis for this area discusses a problem where control and power cables for all three (3) Unit 1 charging pumps are routed within the fire area. An exemption was provided by the NRC, based upon adequate separation of the power cables between the A train charging pumps (1P-2A and 1P-2B) and the B train pump (1P-2C). For a fire in the vicinity of motor control center 1B32, charging pump 1P-2C is credited, since its associated power cables have adequate separation. However, control cables could be damaged resulting in a loss of speed control. With the loss of control cables, the pump will continue to run at minimum speed, which would be adequate for normal make-up when the RCP seals are not challenged.

The Safe Shutdown Analysis stresses the importance of ensuring continuity of charging, such that the seals are protected from sustained loss of cooling. The coping strategy, contained within the Safe Shutdown Analysis indicates that no manual actions are required outside the control room if control power is lost.

(EIIS Component Identifier: P) 2 (EIIS Component Identifier: MCC) (EIIS Component Identifier: CBL) 4 (EIIS Component Identifier: P) FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) A review of the control cables associated with 1P-2C, indicates that cables are located within Fire Area A06.

If damaged by fire, the pump would not be able to be started from the control room. The Safe Shutdown Analysis did not identify the control cables as required for safe shutdown, and the circuit analysis did not consider the impact of fire damage on the associated control circuit. There are three reasons that the pump may not be running and require a start. First, the pump could be in standby as part of normal pump line-up.

Second, the pump could be tripped on under voltage. Third, the pump could trip due to intra-cable or inter- cable shorts in the control cable. A loss of off-site power is assumed for this scenario. A review of power cables in this fire area confirm that off-site power to Unit 1 could be lost if a fire occurred.

FOP 1.2 (Revision 6) for fire area A06 stated the strategy that should be used if RCP seal injection flow is lost for 10 minutes. Specifically, it requires that seal injection remain isolated. This is in conflict with the Safe Shutdown Analysis, which states that RCP seal cooling must be restored in a timely manner to ensure make-up capability would not be lost as a result of failure of the RCP seals.

Unit 2:

charging pumps. Specifically, a fire in the east side of this Fire Area credits the use of either charging pump 2P-2A or 2P-2B. In this portion of the fire area, power and control power to charging pump 2P-2C is affected and the pump is not credited. The power cables for 2P-2A and 2P-2B are routed through the western portion of the fire area (in the vicinity of 2B-32). An exemption is provided for this separation to ensure availability of the 2P-2A and/or 2P-2B in the event of a fire in the eastern portion of the room. It is also recognized that the fire would affect the speed control of 2P-2A and 2P-2B. For this reason it is important to minimize the interruption of charging flow to RCP seal cooling. If seal cooling would be lost for too long a duration, the resulting leakage could exceed the capability of charging pump(s) operating at minimum flow.

Through a physical walk down of cable routing, it was confirmed that at least one of the control power circuit cables for each of the Unit 2 'A' Train Charging Pumps is routed through the eastern portion of the fire area.

Fire damage to the control cables in this area could result in a total loss of the control circuit.

Neither FOP 1.2 nor the Safe Shutdown Analysis Compliance Strategies provide adequate guidance of manual actions necessary to restart these pumps as necessary to ensure adequate RCP cooling.

Safety Significance:

The plant maintains administrative controls for the introduction of combustible materials and ignition sources to limit the probability of a fire. These areas are also provided with automatic fire detection and suppression systems. The safety significance of this condition continues to be evaluated. Based on these administrative controls and fire protection features, NMC considers the safety significance of this issue to be very low.

NMC will provide a supplement to this LER if the result of the final evaluation indicates more than very low safety significance.

Point Beach Nuclear Plant Unit 1 05000266 i YEAR 1 SEQUENTIAL REVISION LER NUMBER (6 PAGE (3)

Cause:

The cause of this condition was a result of only considering the impact of control circuit damage on the speed control of an operating charging pump, and not the manual actions required to operate the pump should the pump be in standby or tripped due to under voltage or short circuit.

Corrective Action:

Completed:

• Implemented twice per shift compensatory fire watches for Fire Area A06 until resolution of manual actions is complete.

• Revised FOP 1.2 with selected method of recovery and remove option to isolate RCP seal cooling from FOP 1.2, Fire Area A-06.

• Implemented a Mode 4 hold during the Unit 2 outage until FOP 1.2 was revised.

• Revised FOP 1.2 with selected method of recovery and removed options to isolate seal cooling from FOP 1.2 for Fire Area A-15.

Planned:

• Evaluate potential manual actions to resolve this issue.

• Update the Safe Shutdown Analysis with selected method of recovery.

Previous Similar Events:

A review of recent LERs (past three years) identified one event that involved improper routing of electrical cables resulting in inadequate train separation.

LER Number Title 266-2002-002-00 Unit 1 A-Train Reactor Protection Cable Routed in B-Train Cable Trays