ENS 55346
ENS Event | |
|---|---|
01:54 Jul 9, 2021 | |
| Title | Automatic Reactor Trip Due to Main Turbine Trip |
| Event Description | At 2154 EDT on 7/8/2021, with the Unit in Mode 1 at 100% power, the reactor automatically tripped due to trip of the main turbine, caused by failure of a non-safety related breaker during functional testing. Following the reactor trip the Steam Feed Rupture Control System automatically initiated on low Steam Generator 1 level, actuating both turbine-driven Auxiliary Feedwater Pumps. The operators subsequently started the high pressure injection pumps manually per procedure in response to overcooling indications.
Operations responded and stabilized the plant. Decay heat was initially being removed via the Main Condenser. During post-trip response actions, while attempting to shut down the Auxiliary Feedwater Pumps, a low pressure condition was experienced in Steam Generator 2, resulting in isolation of the Main Condenser and steam being discharged through the Atmospheric Vent Valves for decay heat removal. There is no known primary to secondary leakage. Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported in accordance with 10 CFR 50.72(b)(2)(iv)(A) as a four-hour, non-emergency notification of emergency core cooling system (ECCS) discharge into the reactor coolant system, and in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an eight-hour, non-emergency notification of an event that results in a valid actuation of the Auxiliary Feedwater System. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Davis Besse  Ohio (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(B), RPS Actuation | |
| Time - Person (Reporting Time:+-1.17 h-0.0488 days <br />-0.00696 weeks <br />-0.0016 months <br />) | |
| Opened: | Nicholas Buehler 00:44 Jul 9, 2021 |
| NRC Officer: | Kerby Scales |
| Last Updated: | Jul 9, 2021 |
| 55346 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | A/R |
| Before | Power Operation (100 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 553462021-07-09T01:54:0009 July 2021 01:54:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Main Turbine Trip ENS 546112020-03-25T16:40:00025 March 2020 16:40:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Trip Due to Loss of Reactor Coolant Pumps ENS 542632019-09-07T17:09:0007 September 2019 17:09:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip ENS 522322016-09-10T07:43:00010 September 2016 07:43:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Unit Trip Due to Main Generator Lock-Out ENS 516962016-01-29T18:22:00029 January 2016 18:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip Due to Reactor Protection System Actuation ENS 510612015-05-09T22:55:0009 May 2015 22:55:00 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 Unusual Event Declared Due to Steam Leak in the Turbine Building ENS 491592013-06-30T01:20:00030 June 2013 01:20:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Automatic Reactor Trip Due to Reactor Coolant Pump Trip ENS 428282006-09-06T06:31:0006 September 2006 06:31:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Manual Reactor Trip on Loss of Condenser Vacuum ENS 409212004-08-04T14:24:0004 August 2004 14:24:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation Unexpected Reactor Trip During Maintenance Activities 2021-07-09T01:54:00 | |