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A finding of very low safety significance … A finding of very low safety significance with an associated non-cited violation of Technical Specification (TS) 3.0.4 was self-revealed on October 4, 2015, when the licensee inadvertently entered an operation with the potential to drain the reactor vessel (OPDRV) condition while in Mode 5 (refueling) without an operable secondary containment. The licensee failed to provide adequate configuration control of reactor recirculation system boundary isolation valves while establishing conditions to support maintenance during the Cycle 17 refueling outage. As an immediate corrective action, the licensee terminated the OPDRV and restored compliance with the TS by closing recirculation pump seal cavity drain valves to isolate the drain path. In addition, the licensee reviewed all remaining refueling outage system tagouts that interfaced with the reactor vessel to ensure appropriate configuration controls were established to prevent impacting reactor vessel water level, initiated actions to make procedure changes to improve its processes for review of system tagouts for conditions that drain systems that interface with the reactor vessel, and communicated lessons learned from this event with plant operators. The finding was of more than minor safety significance because it was associated with the Configuration Control and Human Performance attributes of the Initiating Events Cornerstone and adversely affected the cornerstone objective of limiting the likelihood of events that upset plant stability and challenge critical safety functions during shutdown, as well as power operations. Specifically, the system tagout error resulted in an inadvertent and uncontrolled loss of reactor coolant system inventory. The finding was determined to be a licensee performance deficiency of very low safety significance during a detailed Significance Determination Process review since the delta core damage frequency was determined to be less than 1.0E7/year. The inspectors concluded this finding affected the cross-cutting area of human performance and the cross-cutting aspect of avoiding complacency. The cause of the event was primarily attributed to a failure to properly use human error reduction techniques, specifically inadequate self-checking by the operators who prepared and reviewed the system tagout configuration for the maintenance, as well as inadequate identification of OPDRV conditions during refueling outage preparations.ions during refueling outage preparations.

Discovered date

23:59:59, 31 December 2015 +

Docket

05000341 +

Event date

23:59:59, 31 December 2015 +

Finding integer

1 +

Finding type

Non-cited violation +

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QA.4 +

IR 05000341/2015004 +

Inspector

R Walton +, T Bilik +, Garrett Hansen +, Billy Dickson +, Nathan Egan +, Brian Kemker +, Chuck Zoia +, Phillip Smagacz +, Thomas Briley + and Stephen Bell +

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>.

12:57:19, 25 September 2017 +

Person