ENS 56241
ENS Event | |
|---|---|
09:00 Nov 28, 2022 | |
| Title | High Pressure Coolant Injection System Inoperable |
| Event Description | The following information was provided by the licensee via email:
At 0400 EST on November 28, 2022, during the performance of Division 2 Residual Heat Removal (RHR) cooling tower fan operability and RHR Service Water valve lineup verification, it was reported that the Mechanical Draft Cooling Tower (MDCT) Fan 'B' was making a loud metallic noise. The cause of the metallic noise is unknown at this time. 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 inoperable cooling water to the HPCI room cooler, per LCO 3.0.6. Investigation into the Division 2 MDCT Fan 'B' abnormal noise 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 following information was provided by the licensee via email: The purpose of this notification is to retract a previous Event Notification 56241 reported on 11/28/2022. On 11/28/22, an event notification to the NRC was made when mechanical draft cooling tower (MDCT) Fan B was declared inoperable and issued Limited Condition of Operation (LCO) 2022-0428 for Division 2 MDCT Fan B abnormal noise. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS) (Technical Specification [TS] 3.7.2). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system (TS 3.7.2), which cools various safety related components, including the High-Pressure Coolant Injection (HPCI) system room cooler (TS LCO 3.0.6). Subsequent inspection and evaluation determined that the brake noise is expected while fans are running at low speeds. This is supported by plant technical procedure, 24.205.10 `Div. 2 RHR Cooling Tower Fan Operability and RHRSW Valve Line-up Verification' (line item 2.2 in Precautions and Limitations) which states `Chatter from the brakes of the MDCT Fans is expected and no cause for discontinuing the test.' The equipment vendor stated that brake chatter is possible and common given that the internal components are free to move along the splined connections. Internal Operating Experience from experienced station operators and maintenance technicians confirmed that the condition is normal and expected. Both Division 2 MDCTs exhibited the same behavior at low speed and passed surveillance testing satisfactorily. No other concerns were noted during fan operation. Therefore, HPCI remained operable and there was no loss of safety function. The event did not involve a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). EN 56241 is retracted and no Licensee Event Report under 10 CFR 50.73(a)(2)(v)(D) is required to be submitted. The NRC Resident Inspector has been notified. Notified R3DO (Stoedter). |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+-0.37 h-0.0154 days <br />-0.0022 weeks <br />-5.06826e-4 months <br />) | |
| Opened: | Whitney Hemingway 08:38 Nov 28, 2022 |
| NRC Officer: | Adam Koziol |
| Last Updated: | May 4, 2023 |
| 56241 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |