05000416/FIN-2017001-02
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Grand Gulf Unplanned Power Changes per 7000 Critical Hours Performance Indicator |
| Description | 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. |
| Site: | Grand Gulf  |
|---|---|
| Report | IR 05000416/2017001 Section 4OA1 |
| Date counted | Mar 31, 2017 (2017Q1) |
| Type: | URI: |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71151 |
| Inspectors (proximate) | E Uribe G Warnick L Carson M Phalen M Young N Day P Elkmann S Hedger |
| INPO aspect | |
| ' | |
Finding - Grand Gulf - IR 05000416/2017001 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Grand Gulf) @ 2017Q1
Self-Identified List (Grand Gulf)
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||