A violation of
TS 3.3.6.1(A.1),
Primary Containment Isolation Instrumentation was identified by the licensee during a review of recent operations logs and
CAP documents on September 7, 2015 by on-shift operators. On September 5, 2015, operators performing shiftly TS rounds identified that the Unit 3, A
main steam line (
MSL) steam flow detector, 3-0261-2A, was reading more than 25 pounds per square inch differential (psid) lower than the other three steam flow detectors on the A
MSL contrary to
Surveillance Requirement 3.3.6.1.1. This issue was entered into the licensees
CAP at this time as
IR 2551890, where the on-shift Senior Reactor Operator (
SRO) recommended performing DIS 0250-01, Dresden Unit 3 Quarterly
Main Steam Line High Flow Switch Calibration and incorrectly assessed
TS 3.3.6.1 function 1.d
Main Steam Line Flow High as being
inoperable but not requiring the failed channel to be placed in trip for the failed steam flow switch. The
SRO incorrectly applied the
operable logic of two required channels on each
MSL per trip system and did not recognize that one failed channel would require entry into
TS 3.3.6.1(A.1).
TS 3.3.6.1(A.1) requires that operators place the failed channel in trip within
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of discovery. Operations on-shift reviews of recent logs and issue reports identified the missed entry into
TS 3.3.6.1(A.1) on September 7, 2015 more than
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> later. The missed TS entry was entered into the licensees
CAP as
IR 2552152. Subsequent performance of DIS 0250-01 identified two additional channels outside of TS required trip values for
MSL high steam flow. The failure to enter a required TS action statement when declaring A
MSL flow detector 3-0261-2A
inoperable was considered a performance deficiency. The finding was determined to be more than minor in accordance with
IMC 0612, Power Reactor Inspection Reports, Appendix B, Issue Screening, dated September 7, 2012, because if left uncorrected, the performance deficiency would have the potential to
lead to a more significant safety concern. Specifically, if left uncorrected, a separate single failure could have prevented the safety function of isolating the A
MSL on a steam line rupture casualty. The inspectors evaluated the finding using
IMC 0609,
Significance Determination Process, Attachment 0609.04, Initial Characterization of Findings, Tables 2 and 3, and Appendix A, The
Significance Determination Process (
SDP) for Findings at Power, Exhibit 3,
Barrier Integrity Screening Questions, dated June 19, 2012. The inspectors answered No to the Appendix A, Exhibit 3
Barrier Integrity Screening Questions, therefore, the finding was determined to be of very low safety significance (Green). Licensee corrective actions included disqualifying the
SRO from shift duties pending remedial training, performing an apparent cause evaluation concerning the missed TS action statement entry, replacing the failed A
MSL flow switch, and calibrating all other channels which were outside the required operating band of DIS 0250-01.
