ENS 40686
ENS Event | |
|---|---|
19:59 Mar 20, 2004 | |
| Title | Invalid Actuation of the Motor Driven Emergency Feedwater Pumps |
| Event Description | By design, the Steam Generator (SG) Dry-out Protection Circuit actuates whenever two level indications (two of two actuation logic) in either SG are lower than the setpoint for more than 30 seconds. This start circuit is not credited in any ONS safety analysis, therefore this signal is considered an INVALID signal with respect to 50.73 (a)(2)(iv)(A). Upon actuation, the circuit starts both Motor Driven Emergency Feedwater Pumps (MDEFWPs) on the affected unit. It does not send a start signal to the Turbine Driven Emergency Feedwater Pump.
Shortly after entering Mode 4, a control operator stopped one of two operating Reactor Coolant Pumps per the Unit shutdown procedure. A second control operator was manually controlling Feedwater and reduced flow to control the system cooldown rate, without recognizing that the 2B SG had reached the low level setpoint for SG Dry-out Protection Circuit actuation. In this event, the 2B SG level trains A and B indicated lower than the setpoint value (-21 inches) for more than 30 seconds, so the SG Dry-out Protection Circuit started the 2A and 2B MDEFWPs. The actuation was considered complete and the system started and functioned successfully. Both MDEFWPs started. The 2B SG control valve, 2FDW-316, opened and fed the 2B SG from the 2B MDEFWP for approximately one minute until the SG level reached the EFDW control setpoint (30 inches). The 2A pump did not feed the 2A SG because 2A SG level remained well above the EFDW control setpoint so there was no demand for the 2A SG control valve, 2FDW-315, to open. The licensee notified the NRC Resident Inspector.
|
| Where | |
|---|---|
Oconee  South Carolina (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+735.93 h30.664 days <br />4.381 weeks <br />1.008 months <br />) | |
| Opened: | Randy Todd 10:55 Apr 20, 2004 |
| NRC Officer: | Arlon Costa |
| Last Updated: | Apr 26, 2004 |
| 40686 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Shutdown (0 %) |
| After | Hot Shutdown (0 %) |
WEEKMONTHYEARENS 480302012-04-23T00:58:00023 April 2012 00:58:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Keowee Hydro Power Station Automatically Started Based on an Invalid Signal ENS 465442010-11-18T07:45:00018 November 2010 07:45:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Motor Driven Emergency Feedwater System ENS 451802009-05-19T20:09:00019 May 2009 20:09:00 10 CFR 50.73(a)(1), Submit an LER Invalid Feedwater System Actuation While Shutdown ENS 431462006-12-09T02:43:0009 December 2006 02:43:00 10 CFR 50.73(a)(1), Submit an LER Invalid Efw Actuations Due to an Issue in Sg Dryout Protection Circuit ENS 416492005-04-29T05:05:00029 April 2005 05:05:00 10 CFR 50.73(a)(1), Submit an LER Emergency Hydro Generators Auto Start - Unknown Cause ENS 406862004-03-20T19:59:00020 March 2004 19:59:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of the Motor Driven Emergency Feedwater Pumps 2012-04-23T00:58:00 | |