05000315/LER-2007-002

LER-2007-002, Failure to Declare Essential Service Water Inoperable

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
Initial Reporting
3152007002R00 - NRC Website

Conditions Prior to Event Mode 1 - 100 percent power

Description of Event

On October 5, 2007, with Unit 1 operating at 100% power and Unit 2 in a refueling outage (Mode 6 - defueled), a Unit 2 plant battery was removed from service. The Unit 1 control room crew was not aware of this Unit 2 activity. Later in the shift, while verifying equipment status to assure compliance with Technical Specifications (TS), the Shift Technical Advisor (STA) identified the cross-unit TS impact of removing the battery from service that the operating crew had not recognized.

At the time of discovery, Unit 1 West Essential Service Water (ESW) and Unit 2 East East ESW pump be OPERABLE. Also, for this condition, Unit 1 TS 3.8.4 requires that the Unit 2 250-volt DC power source (including the associated plant battery) supplying the Unit 2 East ESW pump be OPERABLE, and Unit 1 TS 3.8.9 requires that the Unit 2 250-volt DC distribution system supplying the Unit 2 East ESW pump be OPERABLE. With the Unit 2 250-volt DC buses cross-tied and the plant battery removed from service, the required power source and distribution systems supporting the Unit 2 East ESW pump were not OPERABLE. Because the Unit 2 East ESW pump was cross-tied with the Unit 1 West ESW pump, action requirements for Unit 1 TS 3.8.4 and 3.8.9 applied. The required action was to declare the Unit 1 West ESW pump inoperable.

At the time the STA identified the condition, the Unit 1 West ESW pump was already considered inoperable. However, a Unit 1 control room log entry was made documenting entry into the TS 3.8.4 and 3.8.9 action requirements.

An extent of condition review was performed to determine if unrecognized TS 3.8.4 or 3.8.9 entries had previously occurred under similar circumstances. Outage activities during the current Unit 2 refueling outage prior to October 5, 2007, were reviewed, as were activities during the Unit 1 refueling outage in the Fall of 2006.

Three cases were identified where unrecognized entry into TS 3.8.4 and 3.8.9 action requirements occurred and the required action to immediately declare the affected unit's ESW train inoperable was not taken. These cases are:

• Unit 1 East ESW train between 2040 hours0.0236 days <br />0.567 hours <br />0.00337 weeks <br />7.7622e-4 months <br /> on September 15, 2007, and 1605 hours0.0186 days <br />0.446 hours <br />0.00265 weeks <br />6.107025e-4 months <br /> on September 18, 2007

• Unit 1 East ESW train between 0622 and 0625 hours0.00723 days <br />0.174 hours <br />0.00103 weeks <br />2.378125e-4 months <br /> on September 19, 2007

• Unit 2 West ESW train between.2310 and 2320 hours0.0269 days <br />0.644 hours <br />0.00384 weeks <br />8.8276e-4 months <br /> on October 4, 2006 These events are reportable as a licensee event report in accordance with 10 CFR 50.73(a)(2)(i)(B).

Cause of Event

The cause of these events was a failure of the Improved TS implementation process to identify and establish appropriate barriers to ensure that the requirements of TS 3.8.4 and 3.8.9 would be met.

When the Improved TS were implemented, new provisions were incorporated in TS 3.8.4 and 3.8.9 specifically requiring OPERABILITY of opposite-unit 250-volt DC power sources and distribution systems for cross-tied ESW systems. However, the procedures that are used to cross-tie a unit's 250-volt DC buses and remove a plant battery from service were not modified to incorporate precautions or other procedure steps to ensure that the opposite unit was informed of the activity and the cross-unit TS impact was addressed. No positive controls were incorporated into the outage work control process to ensure that the cross-unit impact of removing a plant battery from service was addressed prior to performing the activity.

Analysis of Event

Although the condition rendered the ESW trains inoperable, they remained fully functional and capable of providing sufficient cooling water flow to the opposite unit if needed. Thus, the failure to declare the associated unit's ESW train inoperable did not alter the risk associated with the configuration to either unit for the event discussed above.

The required action of TS 3.8.4 and 3.8.9 is to declare an operating unit's ESW pump inoperable when it is cross-tied to the outage unit's pump for which the associated plant battery is out of service. This declaration of inoperability would invoke a 72-hour action requirement via TS 3.7.8 for restoration to OPERABLE status. In all three cases where declaration of inoperability was missed, the 72-hour time limit for restoration was not exceeded and the physical plant configuration was as allowed by TS. Therefore, the failure to complete the declaration of inoperability required by TS 3.8.4 and 3.8.9 had no impact on plant safety.

Corrective Actions

Both units' procedures for battery cross-tie operations will be enhanced to incorporate the necessary controls to address the cross-unit impact of removing a plant battery from service prior to performing that activity.

Training will be provided to licensed operators regarding the cross-unit impact of removing a plant battery from service with respect to the requirements of TS 3.8.4 and 3.8.9.

Previous Similar Events

None.