ENS 47859: Difference between revisions
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| event date = 02/25/2012 01:38 EDT | | event date = 02/25/2012 01:38 EDT | ||
| last update date = 04/24/2012 | | last update date = 04/24/2012 | ||
| title = Invalid Actuation | | title = Invalid Actuation of Standby Gas Treatment Secondary Containment Isolation Valves (Scivs) | ||
| event text = During restoration of Unit 1 reactor protection system (RPS) following preventive maintenance (PM), a link was closed on February 25, 2012 at 0138 EST that resulted in the automatic actuation of the standby gas treatment (SGT) trains for Units 1 and 2 and the automatic isolation of the associated SCIVs (Secondary Containment Isolation Valves). The instruments that input to the actuation logic were in the tripped condition during the performance of the PM with links opened to preclude the automatic response of the SCIVs. The PM procedure did not contain the necessary steps to ensure that the associated instruments that input into the actuation logic were reset prior to reclosing the links that were previously opened to disable their input to the logic. Reclosing the first link associated with a Unit 1 reactor building high radiation monitor trip resulted in an actuation signal that caused the Unit 1 and 2 SGT trains to automatically start as designed, Unit 1 and 2 reactor building normal ventilation to shut down and the Unit 1 and 2 SCIVs to automatically close. This actuation was therefore not the result of a valid signal. The automatic actuation of the SGT system and the isolation of Unit 1 and 2 SCIVs are considered an invalid actuation since the parameters that cause this actuation to occur had not been exceeded. For this reason the actuation is considered invalid and a report to the NRC is not required by 10CFR50.72(b)(3)(iv); however, because the secondary containment isolation signals affected containment isolation valves in more than one system (Unit 1 and 2 components affected) the event is reportable as required by 10CFR50.73(a)(2)(iv)(B)(2). A licensee event report (LER) is required, but a telephone notification is allowed by 10CFR50.73. In the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. The affected procedure(s) will be revised to ensure the affected instruments are reset prior to returning the system to service to preclude recurrence during the performance of future RPS PM activities. | | event text = During restoration of Unit 1 reactor protection system (RPS) following preventive maintenance (PM), a link was closed on February 25, 2012 at 0138 EST that resulted in the automatic actuation of the standby gas treatment (SGT) trains for Units 1 and 2 and the automatic isolation of the associated SCIVs (Secondary Containment Isolation Valves). The instruments that input to the actuation logic were in the tripped condition during the performance of the PM with links opened to preclude the automatic response of the SCIVs. The PM procedure did not contain the necessary steps to ensure that the associated instruments that input into the actuation logic were reset prior to reclosing the links that were previously opened to disable their input to the logic. Reclosing the first link associated with a Unit 1 reactor building high radiation monitor trip resulted in an actuation signal that caused the Unit 1 and 2 SGT trains to automatically start as designed, Unit 1 and 2 reactor building normal ventilation to shut down and the Unit 1 and 2 SCIVs to automatically close. This actuation was therefore not the result of a valid signal. The automatic actuation of the SGT system and the isolation of Unit 1 and 2 SCIVs are considered an invalid actuation since the parameters that cause this actuation to occur had not been exceeded. For this reason the actuation is considered invalid and a report to the NRC is not required by 10CFR50.72(b)(3)(iv); however, because the secondary containment isolation signals affected containment isolation valves in more than one system (Unit 1 and 2 components affected) the event is reportable as required by 10CFR50.73(a)(2)(iv)(B)(2). A licensee event report (LER) is required, but a telephone notification is allowed by 10CFR50.73. In the case of an invalid actuation reported under 10CFR50.73(a)(2)(iv), other than actuation of the reactor protection system (RPS) when the reactor is critical, the licensee may, at its option, provide a telephone notification to the NRC Operations Center within 60 days after discovery of the event instead of submitting a written LER. The affected procedure(s) will be revised to ensure the affected instruments are reset prior to returning the system to service to preclude recurrence during the performance of future RPS PM activities. | ||
The four Standby Gas Treatment (SBGT) fans auto started and both Unit 1 and Unit 2 reactor building and refueling floor normal ventilation systems automatically shutdown and isolated as designed. The SBGT initiation and the ventilation system shutdown were both complete actuations. | The four Standby Gas Treatment (SBGT) fans auto started and both Unit 1 and Unit 2 reactor building and refueling floor normal ventilation systems automatically shutdown and isolated as designed. The SBGT initiation and the ventilation system shutdown were both complete actuations. | ||
Latest revision as of 21:04, 1 March 2018
| Where | |
|---|---|
Hatch  Georgia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1419.23 h59.135 days <br />8.448 weeks <br />1.944 months <br />) | |
| Opened: | Daniel Komm 07:52 Apr 24, 2012 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Apr 24, 2012 |
| 47859 - NRC Website
| |