ENS 51152
ENS Event | |
|---|---|
16:07 Apr 15, 2015 | |
| Title | Invalid Actuations of the Containment Ventilation Isolation System |
| 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 two related invalid actuations of the Containment Vent Isolation System at Watts Bar Nuclear Plant Unit 1 (WBN-1).
On April 14, 2015 at 2101 EDT, a sample pump failed on the WBN-1 Train B containment purge exhaust radiation monitor (1-RM-90-131), prompting control room operators to enter Conditions A and B of Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.6, Containment Vent Isolation Instrumentation and Condition A of LCO 3.6.3, Containment Isolation Valves. On April 15, 2015 at 1207 EDT, 1-RM-90-131 radiation readings increased sharply (spiked), initiating an invalid Containment Vent Isolation (CVI) actuation. The spike occurred following troubleshooting and repairs to 1-RM-90-131 when maintenance technicians agitated the motor starter enclosure in an attempt to free a stuck auxiliary contact that controls local indication. As a result of the CVI actuation, flow to lower containment radiation monitor (1-RM-90-106) was isolated, prompting control room operators to enter Condition B of LCO 3.4.15, RCS Leakage Detection Instrumentation. At 1634 EDT, control room operators exited the TS 3.4.15 condition when 1-RM-90-106 was returned to service. On April 17, 2015 at 1327 EDT, control room operators exited LCO 3.3.6 Conditions A and B and LCO 3.6.3 Condition A when sample pump repairs were completed on 1-RM-90-131. On April 19, 2015 at 1550 EDT, 1-RM-90-131 radiation readings spiked and initiated a CVI, prompting control room operators to enter TS LCO 3.4.15 Condition B and LCO 3.3.6 Condition A, until flow was restored to 1-RM-90-106 at 1636 EDT and 1-RM-90-131 was returned to service on April 26, 2015 at 1229 EDT. Each CVI was documented in accordance with the corrective action program, and TVA completed an equipment apparent cause evaluation (CR 1015781) that revealed the cause of the two CVI actuations was the result of a faulted Start/Stop control unit. TVA replaced the faulted control unit. In both instances, the CVI actuations resulted from invalid signals and were limited to a single piece of Train B equipment. There was no loss of safety function and there were no actual safety consequences during the events. The NRC Resident Inspector has been informed. |
| Where | |
|---|---|
Watts Bar  Tennessee (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1390.75 h57.948 days <br />8.278 weeks <br />1.905 months <br />) | |
| Opened: | Matthew Miller 14:52 Jun 12, 2015 |
| NRC Officer: | Daniel Mills |
| Last Updated: | Jun 12, 2015 |
| 51152 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 562742022-11-24T21:21:00024 November 2022 21:21:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-DAY Optional Telephonic Notification of Invalid Actuation of Containment Ventilation Isolation Valves ENS 548702020-07-23T13:56:00023 July 2020 13:56:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for Two Invalid Containment Ventilation Isolation Actuations ENS 542202019-07-26T14:03:00026 July 2019 14:03:00 10 CFR 50.73(a)(1), Submit an LER Invalid Containment Ventilation Isolation Actuation ENS 538402018-12-02T05:28:0002 December 2018 05:28:00 10 CFR 50.73(a)(1), Submit an LER Invalid Containment Ventilation Isolation Actuation ENS 527902017-04-28T09:00:00028 April 2017 09:00:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Auxiliary Feedwater Actuation ENS 525392016-12-15T18:32:00015 December 2016 18:32:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Optional Telephonic Notification for an Invalid Containment Ventilation Isolation Actuation ENS 520012016-04-14T18:06:00014 April 2016 18:06:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Containment Vent Isolation Actuation ENS 511522015-04-15T16:07:00015 April 2015 16:07:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuations of the Containment Ventilation Isolation System ENS 510792015-03-17T17:06:00017 March 2015 17:06:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Auxiliary Feedwater System During Electrical Testing ENS 501332014-04-16T05:48:00016 April 2014 05:48:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for Inadvertent Fast Start of Diesel Generator During Testing ENS 482042012-06-19T03:49:00019 June 2012 03:49:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Ventilation Isolation ENS 441602008-02-23T04:00:00023 February 2008 04:00:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Verbal Notification of Invalid Specified System Actuation ENS 411832004-09-15T14:14:00015 September 2004 14:14:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Containment Vent Isolation Valve 2022-11-24T21:21:00 | |