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The inspectors documented a self-revealing … The inspectors documented a self-revealing Green NCV of TS 5.4.1.a for Exelons failure to implement procedures as required by RG 1.33, Appendix A, Section 8, Procedures for Control of Metering and Testing Equipment and for Surveillance Tests, Procedures, and Calibrations, during maintenance which resulted in a manual isolation valve (1HVFW-1804) being incorrectly placed in the closed position. This human performance error isolated the number 12 steam generator (SG) wide range level transmitter (1LT1124C) and subsequently rendered the auxiliary feedwater actuation system (AFAS) sensor channel ZF inoperable for 33 hours and 39 minutes, a condition prohibited by TS 3.3.4, Engineered Safety Features Actuation System (ESFAS) Instrumentation. The inspectors determined that the failure to properly implement procedure STP M-525AT-1 and place 1HVFW-1804 in its required position was a performance deficiency that was reasonably within Exelons ability to foresee and prevent. Upon identification, Exelon staff entered this issue into their CAP as condition report (CR)-2014-003320. Exelons immediate corrective action was to enter TS 3.3.4.A, to determine and correct the cause, and to retest the system for proper operation. The inspectors reviewed IMC 0612, Appendix B, Issue Screening, and determined the issue is more than minor because it adversely affected the configuration control attribute of the Mitigating Systems cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, Exelon operated with manual isolation valve, 1HVFW-1804 closed which resulted in the inoperability of the AFAS sensor channel ZF for approximately 33 hours and 39 minutes. In accordance with IMC 0609, Attachment 4, Initial Characterization of Findings, issued on June 19, 2012, and IMC 0609, Appendix A, The Significance Determination Process for Findings at Power, Exhibit 2, Mitigating Systems Screening Questions, issued on June 19, 2012, the inspectors determined that a detailed risk evaluation was necessary to disposition the significance of this finding because the finding represented an actual loss of function of at least a single train of AFAS for greater than its TS allowed outage time. A regional SRA performed a detailed risk evaluation. The finding was determined to be of very low safety significance (Green) because the redundant AFAS sensor was operable and functional to ensure actuation of the system if it had been required, therefore there was no loss of the system function. Additionally, the unit was in Mode 3 with very low decay heat levels during the time the ZF sensor channel was determined to be inoperable and plant procedures exist to manually start the AFW system if failure of automatic actuation were to occur. The inspectors determined that the finding has a cross-cutting aspect in the area of Human Performance, Challenge the Unknown, because Exelon did not stop when faced with an uncertain condition about the position of 1HVFW- 1804. Specifically, personnel conducting the second verification did not appropriately question the position of isolation valve 1HVFW-1804 because of the higher experience level of the personnel conducting the first verification.rsonnel conducting the first verification.

Discovered date

23:59:59, 31 December 2015 +

Docket

05000317 +

Event date

23:59:59, 31 December 2015 +

Finding integer

2 +

Finding type

Non-cited violation +

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Hours

3.819444e-4 d (0.00917 hours, 5.456349e-5 weeks, 1.25565e-5 months) +

INPO aspect

QA.2 +

Identified by

NRC identified +

Inspection Manual Chapter

NRC Inspection Manual 0609 +, NRC Inspection Manual 0612 Appendix B + and NRC Inspection Manual 0609/Appendix A, The Significance Determination Process (SDP) for Findings At-Power +

Inspection procedure

IP 71153, Event Followup +

Inspection report

IR 05000317/2015004 +

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12:58:23, 25 September 2017 +