ENS 52228
ENS Event | |
|---|---|
12:50 Jul 12, 2016 | |
| Title | Invalid Actuation of Both Trains Essential Spray Pond System |
| Event Description | The following event description is based on information currently available. If through subsequent reviews of this event additional information is identified that is pertinent to this event or alters the information being provided at this time a follow-up notification will be made via the ENS or under the reporting requirements of 10CFR50.73.
This telephone notification is being made pursuant to the reporting requirements of 10CFR50.73(a)(2)(iv)(A) and 50.73(a)(1) to describe an invalid actuation of both trains of the Palo Verde Nuclear Generating Station (PVNGS) Unit 2 essential spray pond (SP) system. The SP system serves as an emergency service water system that does not normally run and serves as an ultimate heat sink as described in 10CFR50.73(a)(2)(iv)(B)(9). On July 12, 2016, at approximately 0550, Mountain Standard Time, Unit 2 experienced a manual actuation of both trains of the SP system. Approximately 20 minutes earlier, the failure of a +15VDC power supply on the containment purge isolation actuation signal (CPIAS) module resulted in a trip of the B train CPIAS and a momentary cross trip of the A train CPIAS, and both trains of the control room essential filtration actuation system (CREFAS). These brief actuation signals resulted in starting of some but not all essential equipment because the actuation signals cleared before most of the equipment received a start signal. Both trains of the SP system were started manually in accordance with the alarm response procedure. The A train CPIAS and both trains of CREFAS were reset. The B train CPIAS remained in a partially tripped state because of the failed power supply. The manual actuation of both A and B trains of the SP system was complete. Both trains of the SP system started and functioned successfully. The invalid actuation was the consequence of a failed +15VDC power supply on the B train CPIAS module which resulted in momentary trips of both trains of CPIAS and CREFAS. The containment building radiation monitors that actuate CPIAS exhibited normal radiation levels which would not have required CPIAS actuation. The event was entered into the PVNGS corrective action program. There was no adverse impact to public health and safety nor to plant employees. The NRC Resident Inspectors have been informed. |
| Where | |
|---|---|
Palo Verde  Arizona (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1395.37 h58.14 days <br />8.306 weeks <br />1.911 months <br />) | |
| Opened: | Jorge Rodriquez 16:12 Sep 8, 2016 |
| NRC Officer: | Steve Sandin |
| Last Updated: | Sep 8, 2016 |
| 52228 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 559262022-04-12T03:45:00012 April 2022 03:45:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation ENS 550322020-12-11T07:00:00011 December 2020 07:00:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Option Telephonic Notification of an Invalid Specified System Actuation ENS 547012020-03-14T19:44:00014 March 2020 19:44:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Spray Pond Pump System - 60 Day Reports ENS 524132016-10-17T22:19:00017 October 2016 22:19:00 10 CFR 50.73(a)(1), Submit an LER Invalid Engineered Safety Features Actuation System (Esfas) Signal ENS 522282016-07-12T12:50:00012 July 2016 12:50:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of Both Trains Essential Spray Pond System ENS 498072013-12-12T03:11:00012 December 2013 03:11:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Report for an Invalid Main Steam Line Actuation ENS 486152012-10-26T04:08:00026 October 2012 04:08:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Actuation of the Essential Spray Pond System ENS 468982011-04-03T21:44:0003 April 2011 21:44:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Notification of Invalid Start of the 'A' Emergency Diesel Generator ENS 427342006-06-06T01:44:0006 June 2006 01:44:00 10 CFR 50.73(a)(1), Submit an LER Invalid Emergency Diesel Generator Start ENS 418042005-04-29T07:43:00029 April 2005 07:43:00 10 CFR 50.73(a)(1), Submit an LER Invalid System Actuation 2022-04-12T03:45:00 | |