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A self-revealed finding of very low safety … A self-revealed finding of very low safety significance with an associated NCV of Technical Specification (TS) 3.7.7, Main Turbine Bypass Valves System, was identified on April 18, 2012, when an unplanned reactor scram occurred during generator voltage regulator testing. Inspectors subsequently determined the licensee had failed to identify elimination of a time delay that changed how the system responded to a load reject with no turbine trip during vendor design documentation review for the digital electro-hydraulic control (DEHC) system modification implemented in 2006. Failure to perform the review with the rigor required by CC-AA-103-1003, Owners Acceptance Review of External Engineering Technical Products, is a performance deficiency entered into the licensees corrective action program (CAP) as Issue Report (IR) 1355763. This finding resulted in exceeding the allowed out-of-service time for TS 3.7.7, Main Turbine Bypass System, on at least eleven occasions between the two units since the modifications were installed. The finding was determined to be more than minor because the performance deficiency adversely affected the Reactor Safety - Initiating Events Cornerstone objective to limit the likelihood of those events that upset plant stability and challenge critical safety functions. In this circumstance, the Design Control attribute of the cornerstone was adversely impacted when unintended consequences were introduced during a modification. Using IMC 0609, Attachment 4, Table 4a, Initiating Events Cornerstone, Transient Initiators, inspectors determined that the performance deficiency did not contribute to the likelihood of both a reactor trip and unavailability of mitigation equipment since the main steam safety and relief valves are the credited pressure mitigation equipment and were unaffected by the event. Therefore, this finding screens as Green, or very low safety significance. The inspectors did not identify a cross-cutting aspect for this performance deficiency since it occurred during the DEHC modification review in 2006 and was considered a legacy issue.in 2006 and was considered a legacy issue.

Discovered date

23:59:59, 30 June 2012 +

Docket

05000254 + and 05000265 +

Equipment trip

Turbine Trip + and Reactor Trip +

Event date

23:59:59, 30 June 2012 +

3 +

Non-cited violation +

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Identified by

Self-revealing +

Inspection Manual Chapter

NRC Inspection Manual 0609 +

Inspection procedure

IP 71153, Event Followup +

Inspection report

IR 05000254/2012003 +

Inspector

David Jones +, J Mcghee +, E Sanchez-Santiago +, M Ring +, B Cushman +, C Matthews +, Atif Shaikh + and Robert Orlikowski +

Issue report

AR 01355763 +

Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.

00:45:45, 21 February 2018 +

Person