05000362/LER-2008-003

LER-2008-003, Missed TS completion time results in TS Violation

Docket Number
Event date:	11-30-2008
Report date:	01-30-2009
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3622008003R00 - NRC Website

Event Date: November 30, 2008 Reactor Vendor: Combustion Engineering Mode: Mode 4 — Hot Shutdown Power: 0 Percent

Description of Event:

San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 has eight Class 1 E 125 VDC Station Batteries [E,1]; 4 for each unit. In Unit 3, 125 VDC Station Battery 3B010 supplies power to Vital Bus 3D4.

Technical Specification (TS) 3.8.6, "Battery Cell Parameters," provides the applicable Limiting Condition for Operation (LCO), Actions, and Surveillance Requirements (SR)s associated with the 125 VDC Station Batteries. If a battery has one or more cells that are not within TS required parameters, TS 3.8.6, Action "A.1" requires SCE to verify battery pilot cells meet certain Category "C" values are within one hour; Action "A.2" requires verification that all battery cells meet certain Category "C" parameters within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; Action "A.3" requires restoration of battery cell parameters to all Category "A" and "B" parameters within 31 days. If these actions are not met, SCE is required to immediately declare the affected battery inoperable and enter the actions required by applicable TS.

TS 3.8.4, "DC Sources — Operating," provides the Limiting Condition for Operation (LCO), Actions, and SRs associated with the four trains of DC electrical power subsystems for Modes 1 through 4.

TS 3.8.4. Action "A" requires that with one battery inoperable, the associated DC electrical power subsystem must be restored to operable status within two hours. If this is not met, TS 3.8.4. Action "B" requires that the plant be placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

On October 25, 2008, at about 1437 PDT, with Unit 3 in Mode 4, station battery 3B010 was removed from service for a battery service test. The test was successfully conducted and 3B010 was returned to service on October 30, 2008, at about 0745 PDT, with Unit 3 still in Mode 5. Performance of the service test caused battery 3B010 to not meet the battery cell parameter requirements specified in TS Table 3.8.6-1, "Battery Surveillance Requirements" and required SCE to comply with the TS 3.8.6, Actions "A.1" through "A.3." Completion of TS 3.8.6 Action "A.3" was due on November 30, 2008.

On December 1, 2008 (discovery date), at about 0859 PST,with Unit 3 in Mode 4, SCE recognized that TS 3.8.6 Action "A.3" was not completed within 31 days following the battery service test and declared the battery inoperable. SCE entered TS 3.8.4 Action "B" at 10:59 PST. By 14:15 on December 1, 2008, SCE had completed the action required by TS 3.8.6 Action A.3 and restored battery 3B010 to Operable status. This sequence of events resulted in a violation of TS 3.8.6 for failing to complete the required actions within the TS completion time.

On November 30, 2008 (event date), at about 1501 PST, Unit 3 entered Mode 4, "Hot Standby." In Mode 4, the TS required all four trains of Batteries to be Operable, including 3B010. At that time, the missed 31 day action had not been discovered and Plant Operators could not have known that 3B010 should have been considered inoperable. Nevertheless, the TS required Operators to follow the required actions of TS 3.8.4.

SCE is reporting these occurrences in accordance with 10CFR50.73(a)(2)(i)(B).

Cause of the event:

SCE cause evaluation concluded that this event occurred due to the lack of a formal process to track and ensure that battery related 7-day and 31-day actions are completed on time. Instead, SCE was relying on the Maintenance personnel to track these required actions. This was not a robust tracking process and was vulnerable to a single point error.

Corrective Actions:

SCE successfully completed the 31 day surveillance inspection on December 1, 2008. SCE will review this event with the appropriate personnel.

SCE will revise the template for the battery service test and the battery performance test to require the 7 day and 31 day actions to be included in the associated work plans as separate operations within each surveillance work order and to ensure appropriate scheduling within the applicable work orders.

SCEs formal cause evaluation for this event is ongoing. This LER will be updated if the cause evaluation reveals any new significant causes or corrective actions.

Safety Significance:

When SCE completed the 31 day action on December 1, 2008, all battery parameters were in specification and the battery was confirmed to be operable. Consequently, SCE concludes there was no safety significance to this event.

Additional Information:

In the last three years, SCE reported one other instance of failing to comply with a station battery related TS. Unit 2 LER 2008-008, dated December 19, 2008, reported a TS violation that resulted when spare battery BOOX was placed in service without all required surveillances completed. The cause of that event was a failure to properly implement a transition plan for scheduling TS surveillances while SONGS transitioned from a previous work tracking tool (MOSAIC) to the newer ERP System.