River Bend: Unreliable Nuclear Plant instrumentation Power Supplies

One is safety related instrumentation power supplies and the other one is a so called non safety instrumentation power supplies. Either way, it effects plant reliability. I believe any plant scram prematurely wears out safety equipment.

 

Basically these two LERs are the ones on the last two plant scram.

Licensee Event Report 50-458 /2014-006-00 

The Christmas plant trip: Power was lost when the output breaker on the RPS motor-generator (MG) in the Division 2 subsystem tripped. The mostly likely cause of the output breaker trip was an intermittent failure of the MG field flash card due to a degraded capacitor. The capacitor was replaced, and the MG was tested and returned to a standby condition as a backup power supply. The alternate power supply will remain in service carrying the bus until completion of a modification to eliminate the field flash card as a potential source of recurrence of this problem

Licensee Event Report 50-458 /2015-005-00

On June 1, 2015, at 9:09 p.m. CDT, with the plant operating at 90 percent power, an unplanned automatic reactor scram occurred due to low reactor water level. This event resulted from the loss of a non-safety related instrument power panel, apparently caused by an internal electrical transient in a 125-volt AC / DC inverter. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A)as the automatic actuation of the reactor protection system.