One self-revealed finding of very low safety significance was identified for the failure to install a
grommet seal on the
main turbine thrust bearing probes as required by a site design standard, VTD-SKFI-0001, Eddy Probe Systems Technical Manual, during the Unit 1 2009 turbine failure restoration project. Consequently, oil migrated into the thrust bearing probe conduit, which contributed to a main
turbine trip and resultant
automatic reactor trip on September 7, 2011. For corrective actions, the licensee separated the
main turbine thrust bearing probe cables into separate conduits; wrapped the cables in additional shielding and insulation to prevent signal
coupling; and installed sealing glands on the
main turbine thrust housing to eliminate oil intrusion into the conduits. This issue was entered into the licensees corrective action program (
CAP) as Action Request (
AR) 2011-10107. One self-revealed finding of very low safety significance was identified for the failure to install a
grommet seal on the
main turbine thrust bearing probes as required by a site design standard, VTD-SKFI-0001, Eddy Probe Systems Technical Manual, during the Unit 1 2009 turbine failure restoration project. Consequently, oil migrated into the thrust bearing probe conduit, which contributed to a main
turbine trip and resultant automatic
reactor trip on September 7, 2011. For corrective actions, the licensee separated the
main turbine thrust bearing probe cables into separate conduits; wrapped the cables in additional shielding and insulation to prevent signal
coupling; and installed sealing glands on the
main turbine thrust housing to eliminate oil intrusion into the conduits. This issue was entered into the licensees corrective action program (
CAP) as Action Request (
AR) 2011-10107.
