ENS 52640
ENS Event | |
|---|---|
05:42 Mar 25, 2017 | |
| Title | Refueling Water Tank Level Inadvertently Lowered Below Ts |
| Event Description | While performing a purification subsystem alignment on the Unit-2 Refueling Water Tank, an inadvertent transfer of Refueling Water Tank level to the common Spent Fuel Pool occurred. This transfer resulted in lowering Unit-2 Refueling Water Tank level below the Technical Specification [TS] required limit for the current mode of operation at 0142 [EDT] on 3/25/17. Upon recognition of the inadvertent transfer, Operations secured the lineup and restored Unit-2 Refueling Water Tank level to its normal operating band at 0225 on 3/25/17.
This event is reportable under 10 CFR 50.72(b)(3)(v)(D) '...any event or condition that at the time of discovery could have prevented the fulfillment of the safety function structures or systems that are needed to mitigate the consequences of an accident.' With less than the required Technical Specification volume in the Refueling Water Tank, insufficient volume existed in the Refueling Water Tank to maintain 30 minutes of full flow Safety Injection, and subsequent continued pump operation after transition to recirculation mode of operation. This level is required by Technical Specification 3.5.4.B and has a one hour action statement to restore level. The NRC Resident Inspector has been notified.
The purpose of this notification is to retract ENS notification 52640 made on March 25, 2017 for Calvert Cliffs. After further evaluation, it has been determined that the volume of water in the Unit 2 Refueling Water Tank was never below the TS required volume of 400,000 gallons. The evaluation considered the as-found condition of the level transmitter and the existing environmental conditions of the tank in determining the actual RWT water volume on the day of the event. Therefore, this event does not meet the criteria of 10 CFR 50.72(b)(3)(v)(D) and the ENS report is being retracted. The licensee will notify the NRC Resident Inspector. Notified R1DO (Cook). |
| Where | |
|---|---|
Calvert Cliffs  Maryland (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+3.77 h0.157 days <br />0.0224 weeks <br />0.00516 months <br />) | |
| Opened: | Andrew Mcneil 09:28 Mar 25, 2017 |
| NRC Officer: | Karl Diederich |
| Last Updated: | Mar 30, 2017 |
| 52640 - NRC Website
Loading map... {"minzoom":false,"maxzoom":false,"mappingservice":"leaflet","width":"350px","height":"250px","centre":false,"title":"","label":"","icon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"zoom":6,"defzoom":14,"layers":["OpenStreetMap"],"image layers":[],"overlays":[],"resizable":false,"fullscreen":false,"scrollwheelzoom":true,"cluster":false,"clustermaxzoom":20,"clusterzoomonclick":true,"clustermaxradius":80,"clusterspiderfy":true,"geojson":"","clicktarget":"","imageLayers":[],"locations":[{"text":"\u003Cb\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003E\u003Ca class=\"mw-selflink selflink\"\u003EENS 52640\u003C/a\u003E - \u003Ca href=\"/Calvert_Cliffs\" title=\"Calvert Cliffs\"\u003ECalvert Cliffs\u003C/a\u003E\n\u003C/p\u003E\u003C/div\u003E\u003C/b\u003E\u003Cdiv class=\"mw-parser-output\"\u003E\u003Cp\u003ERefueling Water Tank Level Inadvertently Lowered Below Ts\n\u003C/p\u003E\u003C/div\u003E","title":"ENS 52640 - Calvert Cliffs\n","link":"","lat":38.434263888888886,"lon":-76.44219722222222,"icon":"/w/images/b/be/Constellation_icon.png"}],"imageoverlays":null} | |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |