The following information was provided by the licensee via facsimile:
A Technical Specification (TS)-required plant shutdown was initiated on Point Beach Unit 2 at 11:58 a.m. CST on February 27, 2005. The initiation of the unit shutdown was required by TS 3.8.4, Condition 13, due to the Completion Time of TS 3.8.4 Condition A not being met. Both units were operating at 100% power prior to the event.
At 09:48 CST, offsite transmission network line 151 was lost. The associated electrical transient resulted in the loss of all four required battery chargers. This condition resulted in TS 3.8.4 not being met; however, no associated Actions are provided in TS 3.8.4 for the Condition of four inoperable DC power subsystems, requiring entry of both operating units into TS LCO 3.0.3. LCO 3.0.3 specifies that action be initiated within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to shut down both units. Three of the four required battery chargers were subsequently restored to operable status by 10:00 a.m. CST. As a result, LCO 3.0.3 was exited prior to initiation of power reduction on either unit. During the 12 minutes while less than 3 battery chargers were available, the associated station DC loads were being provided by the station batteries. The DC battery drain during this time was minimal and the DC electrical subsystems remained within their analyzed condition.
At 10:00 a.m. CST, the only remaining inoperable battery charger was swing battery charger D09. D09 had been powering the D02 electrical subsystem at the time due to previously ongoing maintenance on normal battery charger D08.
The continued unavailability of D09 resulted in TS 3.8.4 not being met for both Unit 1 and Unit 2 due to D02 electrical power subsystem becoming inoperable, Required Action 3.8.4 A.1 directs restoring the electrical power subsystem to operable status with a Completion Time of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. At 11:48 a.m. CST, Required Actions 3.8.4 B.1 and B.2 were entered for both units due to the Completion Time of TS 3.8.4 Condition A not being met. This Required Action directs that the units be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Plant operators planned an orderly sequential shutdown of both units and initiated the process by beginning a shutdown of Unit 2 at 11:58 a.m. CST. This condition is reportable per 10 CFR 50.72(b)(2)(i).
At 12:02 p.m. CST, battery charger D09 and electrical subsystem D02 were restored to operable status. This resulted in TS 3.8.4 being met and Conditions 3.8.4 A and B were exited. Reactor power on Unit 2 had only been reduced to approximately 99% power at that time. No shutdown was initiated on Unit 1, which remained at 100% power.
The power reduction on Unit 2 continued in accordance with normal plant procedures governing loss of offsite transmission network line 151. Plant procedures specify a reduction to less than 50% power as a precautionary measure associated with a potential for grid instability under certain postulated conditions.
Both reactors continue to operate in a safe and stable manner.
The licensee stated that the loss of offsite power line 151 (345KV) was due to an insulator problem on a high voltage tower about 7 miles from the plant. The estimated repair and restoration time for line 151 is approximately 2100 CST tonight.
The licensee has notified the NRC Resident Inspector.
