ENS 56278

v t e ENS Event
05:51 Dec 17, 2022
Title	Manual Reactor Scram
Event Description	The following information was provided by the licensee via email: On December 16, 2022 at 2351 CST, with the Unit in Mode 1 at 13 percent power, a manual scram was inserted due to lowering Reactor Pressure Vessel (RPV) pressure, which occurred following an unexpected opening of Main Turbine Bypass Valve 1. All control rods fully inserted. Following actuation of the manual scram, RPV pressure lowered, resulting in an automatic Primary Containment lsolation (PCIS) Group 1 isolation (expected response). The main steam isolation valves and steam line drain valves all closed. The Group 1 [isolation] has been reset allowing RPV pressure control with steam line drains to the main condenser. All systems responded as designed. The plant is stable in Mode 3. Investigation of the bypass valve opening is ongoing. This event is reportable under 10 CFR 50.72(b)(2)(iv)(B) RPS Actuation and 50.72(b)(3)(iv)(A) Specified System Actuation. There was no impact on health and safety of the public or plant personnel. The NRC Senior Resident Inspector has been notified.

ENS 56278 +/-
Where
Cooper Nebraska (NRC Region 4)
Reporting

10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation
LER:	05000298/LER-2022-004 Manual Reactor Scram and Group I Isolation Due to Main Turbine Bypass Valve Failing Open 05000298/LER-2022-004-01 1 for Cooper Nuclear Station Manual Reactor Scram and Group I Isolation Due to Main Turbine Bypass Valve Failing Open
Time - Person (Reporting Time:+-1.8 h-0.075 days <br />-0.0107 weeks <br />-0.00247 months <br />)
Opened:	Aric Harris 04:03 Dec 17, 2022
NRC Officer:	Lloyd Desotell
Last Updated:	Dec 17, 2022
56278 - NRC Website Loading map...
v • d • e

v t e Emergency Notification System
Cooper with 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation
WEEKMONTHYEAR2022-12-17T05:51:00 [Table view]
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