ENS 55866
ENS Event | |
|---|---|
03:55 Apr 29, 2022 | |
| Title | Notice of Unusual Event |
| Event Description | The following is a summary of information provided by the licensee via telephone:
On 04/28/22, at 2355 EDT, with both Sequoyah Unit 1 and 2 in Mode-1, 100 percent, a Notice of Unusual Event was declared due to receiving two seismic alarms and security feeling ground movement. Additionally, security in a tower heard an explosion. Both units remain in Mode-1, 100 percent and they are investigating the validity of the seismic alarms before proceeding with the Abnormal Operating Procedure required shutdown. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee will notify the NRC Resident Inspector. The state of Tennessee and the Tennessee Valley Authority were notified. Notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS NRCC THD Desk(email), and DHS Nuclear SSA (email).
The following is a summary of information provided by the licensee via telephone: On 4/29/22, at 0406 EDT, Sequoyah Unit 1 and Unit 2 terminated the Notice of Unusual Event. The Civil Engineers determined that the alarms were due to a failed seismic indicator channel. Through interviews, only one security officer felt ground movement for a couple of seconds and heard a faint rumbling sound. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The licensee will notify the NRC Resident Inspector. The state of Tennessee and the Tennessee Valley Authority were notified. Notified R2DO (Miller), NRR EO (Miller), and IR MOC (Gott) via email. Additionally, notified DHS SWO, FEMA Operations Center, CISA Central, FEMA NWC (email), DHS NRCC THD Desk(email), and DHS Nuclear SSA (email).
The following information was provided by the licensee via email: SQN [Sequoyah Nuclear Plant] is retracting the previous NOUE [Notice of Unusual Event] declaration made on 4/28/22 at 2355 [EDT] based on Emergency Action Level HU2 for a seismic event greater than Operating Basis Earthquake levels. Following the declaration of the NOUE, the station reviewed all available indications and determined that a seismic event had not occurred. The instrumentation failure was documented under Event Notification #55867. Notified R2DO (Miller), and IR MOC (Gott), NRR EO (Miller) via email. |
| Where | |
|---|---|
Sequoyah  Tennessee (NRC Region 2) | |
| Reporting | |
| Emergency class: | Unusual Event |
| 10 CFR 50.72(a) (1) (i), Emergency Class Declaration | |
| Time - Person (Reporting Time:+-3.6 h-0.15 days <br />-0.0214 weeks <br />-0.00493 months <br />) | |
| Opened: | Brian Klein 00:19 Apr 29, 2022 |
| NRC Officer: | Ossy Font |
| Last Updated: | May 2, 2022 |
| 55866 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 558662022-04-29T03:55:00029 April 2022 03:55:00
[Table view]10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notice of Unusual Event ENS 537542018-11-26T05:00:00026 November 2018 05:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Declared for Excessive Smoke in Containment ENS 476602012-02-12T13:34:00012 February 2012 13:34:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Unusual Event Due to Electrical Fault in 161 Kv Switchyard ENS 462702010-09-23T01:54:00023 September 2010 01:54:00 10 CFR 50.72(a)(1)(i), Emergency Class Declaration Notification of Unusual Event Due to a Transformer Fire ENS 401132003-08-28T20:04:00028 August 2003 20:04:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Alert Declared Due to Reactor Protection System Failure 2022-04-29T03:55:00 | |