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Title 10 of the CFR, Part 50.65(a)(4) requ … Title 10 of the CFR, Part 50.65(a)(4) requires, in part, that before performing maintenance activities the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activities. Wolf Creek Procedure APF 22B-001, Safety Function Status and Assessment Sumary, revision 3, requires that two or more steam generators have greater than 66 percent wide-range water level to be credited for core decay heat removal risk during Mode 5. Otherwise, the assessment escalates risk due to the absence of one method core decay heat removal. Procedure APF 22B-001 is required to be performed daily. Contrary to the above, on February 6, 2012, the licensee failed to assess risk by identifying entry into a Yellow shutdown risk assessment for core decay heat removal due to three of four steam generators being drained to less than 66 percent wide range level. Specifically, while performing the daily shutdown risk assessment, operators failed to identify that planned work to drain and refill the steam generators for cold wet layup chemistry control was to occur on several steam generators simultaneously. Concurrently, the reactor coolant system power operated relief valves were unavailable for feed and bleed, another method of decay removal. Operators recognized the elevated risk after 8 hours with three steam generators being drained below 66 percent water level. This finding is more than minor because it is associated with the equipment performance attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). Specifically, operators failed to identify that they had crossed a shutdown risk management threshold, from Green to Yellow. A Region IV senior reactor analyst verified that the finding was of very low safety significance (Green) and the delta-CDF was less than 1E-6. The licensee has entered this issue into their corrective action program as condition report 48775. action program as condition report 48775.

Discovered date

23:59:59, 31 March 2012 +

Docket

05000482 +

Event date

23:59:59, 31 March 2012 +

Finding integer

4 +

Finding type

Non-cited violation +

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Hours

9.259259e-5 d (0.00222 hours, 1.322751e-5 weeks, 3.044e-6 months) +

Identified by

Licensee-identified +

Inspection report

IR 05000482/2012002 +

Inspector

N O'Keefe +, C Long +, Jim Melfi +, Charley Peabody +, Gary Callaway + and Zachary Hollcraft +

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>.

15:44:42, 30 May 2018 +

Person