ENS 52539
ENS Event | |
|---|---|
18:32 Dec 15, 2016 | |
| Title | 60 Day Optional Telephonic Notification for an Invalid Containment Ventilation 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 Ventilation Isolation (CVI) actuation at Watts Bar Nuclear Plant (WBN) Unit 2.
On December 15, 2016 at 1332 Eastern Standard Time (EST), Unit 2 maintenance personnel were preparing to perform a breaker swap for the normal feed to the 2B1B C and A vent board. When the power was removed from Radiation Monitor 2-RM-90-131, the B Train master isolation signal status panel was unexpectedly lit for CVI. The only automatic action observed from the containment isolation status panel was that 2-FCV-30-037, Lower Compartment Purge Control valve, went closed. The loss of power to 2-RM-90-131 de-energized the relay associated with the high radiation setpoint, resulting in an invalid Train B CVI actuation. During this event, the train B CVI actuation was complete and equipment functioned as designed. Upon identification of the Train B CVI, maintenance activities were halted and a prompt investigation was initiated. WBN found that the work order to perform the breaker swap was planned to lift leads to disable actuation of CVI. The work order lifted the lead for the K622 relay, which was insufficient to prevent the actuation. Two other leads on relays should have been lifted to prevent the actuation in Mode 1. A contributor to this error was that this work had been rescheduled several times prior to actual performance. From the time it was planned to the actual performance, mode changes had been performed on the Unit and no further reviews were performed. 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:+1314.53 h54.772 days <br />7.825 weeks <br />1.801 months <br />) | |
| Opened: | John Tuite 13:04 Feb 8, 2017 |
| NRC Officer: | Dong Park |
| Last Updated: | Feb 8, 2017 |
| 52539 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 570772024-02-16T02:24:00016 February 2024 02:24:00
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