ENS 44561
ENS Event | |
|---|---|
10:08 Oct 11, 2008 | |
| Title | Steam Generator Water Level Trip Actuation Initiated Reactor Trip System |
| Event Description | During plant shutdown to begin a scheduled refueling outage, with the plant at 0% power in Mode 3, an actuation of the reactor trip system (RTS) occurred when a steam generator (S/G) Low-Low water level trip inadvertently occurred during recovery from a feedwater isolation actuation that had previously occurred in response to a steam generator high water level trip condition.
At approximately 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />, plant operators were closing the main steam isolation valves (MSIVs) for plant shutdown. Once the MSIVs were closed, the reactor coolant system (RCS) cooldown rate decreased significantly. The 'A' atmosphere steam dump valve (ASD) was then opened. Shortly after the ASD was opened, the MSIV was also opened. With both the MSIV and ASD open, however, the 'A' S/G water level swelled until the P-14 S/G Hi Level protective interlock setpoint was reached, resulting in a feedwater isolation (FWIS) actuation at 0505 hours0.00584 days <br />0.14 hours <br />8.349868e-4 weeks <br />1.921525e-4 months <br />. Subsequent to the FWIS actuation, plant operators took action to recover from the FWIS in accordance with off-normal operating procedure OTO-SA-00001, 'Engineered Safety Feature Actuation Verification and Restoration.' The motor-driven auxiliary feedwater pumps were started to restore S/G water level. However, S/G water level lowered rapidly in response to the cold auxiliary feedwater flow to the S/G. A S/G Low-Low water level trip signal was then reached on the 'A' S/G, thus resulting in a reactor trip system actuation at 0508 hours0.00588 days <br />0.141 hours <br />8.399471e-4 weeks <br />1.93294e-4 months <br />. All systems functioned normally in response to plant conditions. The NRC Senior Resident Inspector has been informed.
This report is an update to information reported under ENS notification 44561. The original notification reported a valid reactor trip system actuation as a 4-hour notification under 10CFR50.72(b)(2)(iv)(B). The correct reporting requirement is 10CFR50.72(b)(3)(iv)(A), an 8-hour notification, as the plant was in Mode 4 with the reactor subcritical at the time of the event. The [NRC] Resident Inspector will be notified. Notified R4DO (Powers). |
| Where | |
|---|---|
Callaway  Missouri (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+-0.02 h-8.333333e-4 days <br />-1.190476e-4 weeks <br />-2.7396e-5 months <br />) | |
| Opened: | J.R.Weekley 10:07 Oct 11, 2008 |
| NRC Officer: | John Knoke |
| Last Updated: | Oct 12, 2008 |
| 44561 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Shutdown (0 %) |
| After | Hot Shutdown (0 %) |
WEEKMONTHYEARENS 570432024-03-22T01:56:00022 March 2024 01:56:00
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