ENS 42902
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ENS Event | |
|---|---|
22:30 Oct 12, 2006 | |
| Title | Steam Generator Instrumentation Nonconformance |
| Event Description | During a review of two nonconformances documented in the station's corrective action system, an unanalyzed condition which could significantly degrade plant safety was noted. The steam generator level instrumentation was not installed as documented in the UFSAR. Letdown valves and piping inside containment was not installed as described in the UFSAR. An unacceptable scenario is a postulated design basis accident in one of the steam generators and a single failure of the letdown piping in the vicinity of the instrumentation piping of the other steam generator, which could, produce conditions that would mislead the operator as to the condition of the plant during the accident.
This condition was discovered during steam generator replacement when the old steam generators were removed and the instrumentation piping became visible. The replacement piping will be routed in accordance with approved drawings. This piping is not required in the current mode. The licensee notified the NRC Resident Inspector.
Additional review of the situation previously reported has determined that there are no unanalyzed interactions between the SG level instrumentation tubing and the letdown system. The review determined that the previous determination was incorrectly postulating the occurrence of simultaneous accidents. This observation was not readily apparent during the initial review. Therefore this event is not reportable under 10CFR50.72. Event number 42902 is being withdrawn. However, the continuing review has identified a failure which will require reporting under part 50.73, but not 50.72. R4DO (Jeffrey Clark) notified. The NRC Resident Inspector was notified of the retraction of this event by the licensee. |
| Where | |
|---|---|
Ft Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-3.07 h-0.128 days <br />-0.0183 weeks <br />-0.00421 months <br />) | |
| Opened: | Erick Matzke 19:26 Oct 12, 2006 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Nov 7, 2006 |
| 42902 - NRC Website | |
WEEKMONTHYEARENS 522012016-08-25T20:23:00025 August 2016 20:23:00
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