ENS 46709
ENS Event | |
|---|---|
04:10 Mar 30, 2011 | |
| Title | Control Rod Malfunction During Rod Testing Results in Operators Manually Opening Trip Breakers |
| Event Description | Rod L-13 did not function as expected during control rod movement test. This rod is in Shutdown Bank C. When withdrawing this bank, rod L-13 did not withdraw and when the bank was manually inserted, rod L-13 began to withdraw. The [operating] crew went to Enclosure 13.2 of the procedure to deal with the misaligned rods. This enclosure has procedural guidance to open the reactor trip breakers, if desired. The reactor trip breakers were opened and all 211 rods are fully inserted. The reactor was not critical. This activity was performed twice [at the request of reactor engineering].
The licensee will remain in Mode 5 (Cold Shutdown) until troubleshooting and repair is completed. The licensee will be notifying the NRC Resident Inspector.
This notification pertains to Event Number 46709. Based on further investigation, this event is being retracted. The event described in Event Number 46709 involved a control rod malfunction on Unit 2 while in Mode 5, during RCCA movement testing. Specifically, Control Rod 'L-13' in Shutdown Bank 'c' did not move with the bank when the bank was withdrawn from the bottom of the core. When the bank was reinserted to the bottom of the core, L-13 was observed to be 12 steps withdrawn. This condition was corrected by opening the reactor trip breakers which placed L-13 at the bottom of the core. The subsequent troubleshooting plan involved further manipulation of Shutdown Bank 'C' with additional instrumentation on the rod control cabinets. The same anomaly occurred and the reactor trip breakers were again opened. This event (both openings of the reactor trip breakers) was reported to the NRC on 3/30/11 as a valid RPS actuation (8-hour report; 10 CFR 50.72(b)(3)(iv)(A)). The event in question did not result in any consequences, given that the plant was in Mode 5 and not critical. NUREG-1022, Revision 2 states that actuations that need not be reported are those initiated for reasons other than to mitigate the consequences of an event (e.g., at the discretion of the licensee as part of a preplanned procedure). Notwithstanding the issue of whether opening the reactor trip breakers was to mitigate the consequences of an event, NUREG-1022 cites one valid example of actuations that need not be reported, namely if the actuation was 'at the discretion of the licensee as part of a preplanned procedure'. The purpose of the test being conducted was to identify issues with the control rod system. The malfunction that occurred is one of a host of possible issues that could reasonably be expected to occur. Although the test personnel did not go into the test expecting the need to open the reactor trip breakers, the malfunction that occurred resulted in a desire to open the reactor trip breakers in order to restore the plant to the desired configuration. This action was a choice as allowed by the test procedure, and the personnel involved were aware of the result of the action before it occurred. Therefore, the event constituted a 'pre-planned sequence during testing', and was 'at the discretion of the licensee as part of a preplanned procedure.' Based upon the above considerations, the event does not meet the aforementioned criteria for an 8-hour report, and Event Number 46709 is therefore retracted. The licensee has notified the NRC Resident Inspector of this update. Notified the R2DO (Seymour). |
| Where | |
|---|---|
Mcguire  North Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+2.85 h0.119 days <br />0.017 weeks <br />0.0039 months <br />) | |
| Opened: | Tony Cook 07:01 Mar 30, 2011 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Apr 26, 2011 |
| 46709 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 568022023-10-18T15:16:00018 October 2023 15:16:00
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