ENS 55522
ENS Event | |
|---|---|
17:20 Oct 14, 2021 | |
| Title | Traversing IN-CORE Probe a Ball Valve Inoperable |
| Event Description | At 1320 EDT, during a Traversing In-Core Probe (TIP) run for a scheduled Local Power Range Monitors (LPRM) calibration, it was reported to the Main Control Room that TIP A would not fully retract to the In-Shield position. With TIP A unable to fully retract to the In-Shield position the TIP A Ball Valve was declared Inoperable due to not being able to close and meet its safety function in that configuration.
Furthermore the TIP A Shear Valve was previously declared Inoperable due to the Firing Fuses being removed. With the two valves Inoperable the penetration could not be isolated and Primary Containment boundary isolation could not be established. TIP A was subsequently manually hand cranked and placed back into its In-Shield position at 1333 EDT restoring TIP A Ball Valve Operable. This report is being made pursuant to 10CFR50.72(b)(3)(v)(C) based on control the release of radioactive material. The Senior NRC Resident Inspector has been notified.
The purpose of this notification is to retract a previous report made on October 14, 2021 (EN 55522). At 1320 EDT on October 14, 2021 while performing Traversing In-Core Probe (TIP) Machine Gain Adjustment in support of Local Power Range Monitor (LPRM) calibration, an unplanned inoperability of the TIP 'A' Primary Containment Isolation Valve (PCIV) was reported pursuant to 10CFR50.72(b)(3)(v)(C) by EN 55522. On October 14, it was reported to the Main Control Room that TIP 'A' would not fully retract to the In-Shield position. With TIP 'A' unable to fully retract to the In-Shield position, the TIP 'A' Ball Valve PCIV was declared Inoperable due to not being able to close and meet its safety function in that configuration. The TIP 'A' Shear Valve PCIV was previously declared inoperable due to firing fuses being removed. Further investigation determined that a "FAULT: MOVEMENT LIMITED" error was received. This TIP error condition did not present a primary containment isolation issue in the event of a primary containment isolation signal. The Automatic TIP Control Unit (ATCU) is designed to command the TIP drive mechanism to continuously retract a TIP probe to the in-shield position in the event of a containment isolation signal with this condition. In the event of a containment isolation signal, the TIP machine would withdraw the TIP detector back to the in-shield position and the TIP A ball valve PCIV would have closed to perform its safety function. Therefore, the inoperability of TIP 'A' ball valve reported under criterion 10CFR50.72(b)(3)(v)(C) was not met, and EN 55522 is hereby retracted. The NRC Resident Inspector has been notified. Notified R3DO (Peterson) |
| Where | |
|---|---|
Fermi  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material | |
| Time - Person (Reporting Time:+2.12 h0.0883 days <br />0.0126 weeks <br />0.0029 months <br />) | |
| Opened: | Nikolas Schafer 19:27 Oct 14, 2021 |
| NRC Officer: | Bethany Cecere |
| Last Updated: | Nov 24, 2021 |
| 55522 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |