ENS Event | |
|---|---|
17:25 Nov 26, 2017 | |
| Title | Unplanned Emergency Core Cooling System (Eccs) Injection During a Planned Safety Injection Test |
| Event Description | On November 26, 2017, at 1225 Eastern Standard Time (EST), the Watts Bar Nuclear Plant (WBN) Unit 2 experienced an unplanned ECCS discharge to the Unit 2 Reactor Coolant System (RCS) while de-pressurized, in Mode 5, with the Pressurizer vented to the Pressurizer Relief Tank. ECCS injection via the Boron Injection flow path occurred during planned Safety Injection system Engineered Safety Features Actuation System (ESFAS) testing. The Boron Injection flow path should have been isolated and should not have resulted in any injection flow to the Unit 2 RCS. Since the injection was not a part of the pre-planned test this is reportable under 10 CFR 50.72(b)(2)(iv), System Actuation.
All other systems responded as expected in accordance with the ESFAS testing procedure. The unintended ECCS injection flow was isolated and flow through the Boron Injection path was verified to be stopped at 1232 EST. The Unit 2 Pressurizer level and pressure remained below any limits and no safety limits were challenged. NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge | |
| Time - Person (Reporting Time:+-1.15 h-0.0479 days <br />-0.00685 weeks <br />-0.00158 months <br />) | |
| Opened: | Brian Mcilnay 16:16 Nov 26, 2017 |
| NRC Officer: | Michael Bloodgood |
| Last Updated: | Nov 26, 2017 |
| 53092 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 530922017-11-26T17:25:00026 November 2017 17:25:00
[Table view]10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Unplanned Emergency Core Cooling System (Eccs) Injection During a Planned Safety Injection Test ENS 519822016-06-05T16:27:0005 June 2016 16:27:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation, 10 CFR 50.72(b)(2)(iv)(A), System Actuation - ECCS Discharge Reactor Trip and Eccs Actuation Caused by Turbine Governor Valve Failure 2017-11-26T17:25:00 | |