10 CFR 50 Appendix B, Criterion V, Instructions, Procedures, and Drawings, requires activities affecting quality be prescribed by documented procedures which include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. On February 6, 2014,
PPL identified that the startup and shutdown procedures for both Units 1 and 2 were inadequate such that they allowed operation of the
RPV at a vacuum. This resulted in twenty-seven separate violations of
TS 3.4.10,
Reactor Coolant System Pressure and Temperature Limits, which requires
RPV pressure to be maintained within limits at all times. The limits specified by
TS 3.4.10 do not permit operating the
RPV at a vacuum. Contrary to these requirements, on multiple occasions during startup and shutdowns over the past 3 years,
PPL operated the
RPV at a vacuum.
PPL entered this issue into the corrective action program as CR-2014-06949. The inspectors determined that the finding was more than minor because it was associated with the procedure quality attribute of the
Barrier Integrity cornerstone and adversely affected the cornerstone objective to provide reasonable assurance that physical design barriers protect the public from radionuclide releases caused by accidents or events. The inspectors determined through a review of
IMC 0609.04, Initial Characterization of Findings, and Exhibit 3 of
IMC 0609, Appendix A, The
Significance Determination Process for Findings At-Power, issued June 19, 2012, that the finding required a detailed risk evaluation since it was associated with the
reactor coolant system boundary (e.g., pressurized thermal shock). Inspectors determined the finding to be of very low safety significance (Green) based on a qualitative assessment that there was no appreciable effect on the
reactor pressure vessel as a barrier. Specifically, this conclusion was based on review of
PPLs evaluation of acceptability of the
RCS for continued operation, which determined that the stresses on a postulated crack, when the
RPV is under vacuum conditions, would be less than the stresses when the
RPV is under positive pressure conditions.
