Browse wiki

The inspectors identified an URI associate … The inspectors identified an URI associated with the unplanned power changes per 7000 critical hours performance indicator related to events that occurred on June 17, 2016. Description. On June 17, 2016, during turbine stop valve testing, stop valve B was to be cycled closed. Upon performing that action, stop valve B closed as expected; however, stop valve D unexpectedly closed. In response to the unexpected valve closure, the electro-hydraulic control trip fluid pressure fluctuated at an increased rate which caused the turbine control valves to cycle. This valve cycling resulted in numerous unplanned reactor pressure and power changes for approximately 42 minutes. During this time, operations personnel repeatedly performed troubleshooting activities by attempting to reset the stop valves, which caused additional system instability and increased the magnitude of the power oscillations. Ultimately, operations personnel decided to insert control rods in an attempt to stabilize the power and pressure oscillations. The operator action to insert control rods failed to stabilize the power and pressure oscillations, and approximately 1 minute later, an automatic reactor scram occurred due to a valid oscillating power range monitor input to the reactor protection system. This event was documented in Licensee Event Report 05000416/2016004-00, and NRC Inspection Reports 05000416/2016002 and 05000416/2016003. The unplanned power changes per 7000 critical hours performance indicator measures the rate of unplanned power changes per year of operation at power and provides an indication of initiating event frequency. The licensee did not include any unplanned power changes as inputs into this performance indicator for the second quarter of 2016. The inspectors questioned whether any unplanned power changes should have been reported with this performance indicator, and the licensee submitted a frequently asked question (FAQ) to the NRC reactor oversight process working group (ADAMS Accession No. ML17100A235, 03/23/2017 Reactor Oversight Process Working Group Public Meeting). This FAQ (FAQ 17-01) is currently under review to determine whether the above events should be captured as inputs to the unplanned power changes performance indicator. The inspectors concluded that additional inspection would be required to assess whether the unplanned power changes should have been reported in the unplanned power changes per 7000 critical hours performance indicator. This issue was identified as URI 05000416/2017001-02, Grand Gulf Unplanned Power Changes per 7000 Critical Hours Performance Indicator.7000 Critical Hours Performance Indicator.

Discovered date

23:59:59, 31 March 2017 +

Docket

05000416 +

Document

ML17100A235 +

Event date

23:59:59, 31 March 2017 +

Finding

05000416/FIN-2017001-02 + and 05000416/FIN-2016004-00 +

Finding integer

2 +

Finding type

URI +

Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.

IR 05000416/2016002 +, IR 05000416/2017001 + and IR 05000416/2016003 +

Inspector

M Phalen +, E Uribe +, Louis Carson +, Paul Elkmann +, Greg Warnick +, Neil Day +, Matt Young + and Sean Hedger +

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>.

06:02:16, 16 November 2017 +

Person