14:35 Dec 4, 2018
En Revision Imported Date 1/31/2019
EN Revision Text: HPCI INOPERABLE DUE TO MECHANICAL DRAFT COOLING TOWER FAN BRAKE INVERTER FAILURE
At 0935 EST on December 4, 2018, the Division 2 Mechanical Draft Cooling Tower (MDCT) fans were declared inoperable due to failure of the over speed fan brake inverter. The brakes prevent fan over speed from a design basis tornado. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system. The EECW system cools various safety related components, including the High Pressure Coolant Injection (HPCI) system room cooler. An unplanned HPCI inoperability occurred based on a loss of the HPCI Room Cooler. Investigation into why the Division 2 MDCT fan over speed brake inverter failed is in progress. This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability.
The NRC Resident Inspector has been notified.
The purpose of this notification is to retract EN 53772 made on December 4, 2018. Subsequent to the initial notification, the event and site Technical Specifications (TS) were reviewed further. An evaluation determined that TS Limiting Condition for Operation (LCO) 3.0.9 for barriers could be applied to the MDCT fan brakes. As a result of applying TS LCO 3.0.9 to the MDCT fan brakes, it was not necessary to declare the UHS inoperable. With the Division 2 UHS operable on December 4, 2018, the HPCI system was also operable. With HPCI operable, there was no event or condition that could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). Therefore, EN 53772 is retracted and no Licensee Event Report (LER) under 10 CFR 50.73(a)(2)(v)(D) is required to be submitted.
The licensee has notified the NRC Resident Inspector.Notified R3DO (Cameron).
Michigan (NRC Region 3)
|10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident|
|LER:||look for an ler...|
|Time - Person (Reporting Time:+-1 h|
13:35 Dec 4, 2018
|NRC Officer:||Bethany Cecere|
|Last Updated:||Jan 30, 2019|
|53772 - NRC Website|