On October 6, 2011,
PPL declared the Unit 2
HPCI inoperable when trending revealed that the systems EG-M output was erratic, and believed this to be an early indication of the potential governor failure.
PPL determined that the direct cause was a buildup of resistance on the
HPCI overspeed test controller which led to the output fluctuations.
PPLs RCA determined that this was caused by a lack of preventive maintenance or replacement of the
overspeed test controller. Maintenance had not been performed on the controller because it had been incorrectly classified as a criticality Code 6 component, a run to failure component, but should have been classified as a criticality Code 1 component, one requiring preventive maintenance (
PM). This issue was determined to be a violation of
TS 5.4.1, Procedures, which requires that written procedures be established, implemented and maintained as recommended in
Regulatory Guide 1.33, Revision 2, Appendix A, February 1978.
RG 1.33, Appendix A 9.b, requires the development of
PM schedules to specify inspection or replacement of parts that have a specific lifetime.
PPLs procedure NDAP-QA-0524, Revision 14, Equipment Reliability and Station Health Process states that accurate determination of component criticality is necessary to ensure that all equipment meets required levels of performance. Contrary to the above,
PPL did not establish preventive maintenance procedures for the
overspeed test controller because they had also failed to accurately determine the components criticality code. This performance deficiency is more than minor because the finding was associated with the
Mitigating Systems cornerstone attribute of equipment performance, and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that responded to
initiating events to prevent undesirable consequences. The inspectors evaluated the finding using
IMC 0609, Attachment 4, Initial Screening and Characterization of Findings, and determined the finding was Green since it was not a design or qualification deficiency and did not result in a loss of system safety function. The issue was entered into
PPLs CAP as CR 1474781.
