AUTOMATIC ACTUATION OF THE PRIMARY CONTAINMENT ISOLATION SYSTEM
"At 05:35 Eastern Standard Time (EST) on March 5, 2019, with Unit 2 in Mode 5 at 0% power, an actuation of the Primary Containment Isolation System occurred during hydrolazing of the reactor water level variable leg instrumentation line nozzle N011B in the reactor cavity. The hydrolazing activity caused low reactor water level to be sensed on Division II of the shutdown range level instrumentation. Per design, the low level 1 signal resulted in Group 2 (i.e., floor and equipment drain isolation valves), Group 6 (i.e., monitoring and sampling isolation valves) and Group 8 (i.e., shutdown cooling isolation valves) isolations.
"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the Primary Containment Isolation System.
"There was no impact on the health and safety of the public or plant personnel. The Group 8 was reset and shutdown cooling was restored at approximately 05:45 EST.
"The safety significance of this event was minimal. Although there was a brief interruption of the shutdown cooling, the Residual Heat Removal (RHR) shutdown cooling system operation was restored in approximately 10 minutes without extensive troubleshooting or maintenance, and remained operable. The RHR shutdown cooling system is not credited in any Updated Final Safety Analysis Report Chapter 6 or 15 accidents or transients.
"The NRC Resident Inspector has been notified." |