ENS 52001
ENS Event | |
|---|---|
18:06 Apr 14, 2016 | |
| Title | 60-Day Optional Telephonic Notification for an Invalid Containment Vent Isolation Actuation |
| Event Description | This 60-day telephone notification is being submitted in accordance with paragraphs 10 CFR 50.73(a)(1) and 50.73(a)(2)(iv)(A) to report an invalid Containment Vent Isolation (CVI) actuation at Watts Bar Nuclear Plant (WBN) Unit 2.
On April 14, 2016 at 1344 Eastern Daylight Times (EDT), Unit 2 technicians performing calibration checks on the Auxiliary Building general supply fan, connected test equipment to the wrong intake temperature switch, causing an invalid train B auxiliary building isolation (ABI) signal in both Unit 1 and Unit 2. Because the Unit 2 containment purge system was, at that time, configured in the 'refuel' mode, the invalid train B ABI concurrently initiated a train B CVI in WBN Unit 2. Consequently, the train B CVI caused the Unit 2 containment lower compartment radiation monitor to trip and control room operators entered Technical Specification Limiting Condition for Operation (LCO) 3.4.15 RCS Leakage Detection Instrumentation at 1344 EDT. By 1422 EDT, Unit 2 control room personnel had reset the containment purge system and by 1854 EDT had completed procedural steps to restore auxiliary building ventilation to its normal alignment. By 1858 EDT, Unit 2 control room personnel had completed the procedural steps to restore the containment purge system. During this event, the train B ABI and CVI actuations were complete and equipment functioned as designed. Upon identification of the train B ABI/CVI condition, the calibration activities were halted and a prompt investigation was initiated. WBN evaluators determined the apparent cause of the event was incorrect work instructions, with a contributing cause that technicians failed to use human performance error prevention tools to ensure they were calibrating the correct equipment. Personnel responsible for performing the calibration checks have been coached and corrective actions have been taken to correct the work instructions. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1430.57 h59.607 days <br />8.515 weeks <br />1.96 months <br />) | |
| Opened: | David Allen 08:40 Jun 13, 2016 |
| NRC Officer: | Donald Norwood |
| Last Updated: | Jun 13, 2016 |
| 52001 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 570772024-02-16T02:24:00016 February 2024 02:24:00
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