ENS 51965
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ENS Event | |
|---|---|
16:30 May 30, 2016 | |
| Title | Manual Opening Of Reactor Trip Breakers Due To Rod Position Error Greater Than 12 Steps |
| Event Description | On 5/30/2016 at 0930 [PDT], Unit 2 was in its 19th refueling outage in Mode 4 (hot shutdown, reactor subcritical). Routine post-maintenance testing of digital rod position indication (DRPI) was in progress in accordance with Surveillance Test Procedure (STP) R-1C. Rod Shutdown Bank A was being withdrawn. With Shutdown Bank A Group 1 demand indicating 14 steps, and Group 2 demand indicating 13 steps, Bank A DRPI indicated 12 steps but control rod B4 DRPI indication remained at Step 0. With the bank demand position exceeding rod B4's DRPI indication by greater than 12 steps, Operators manually opened the Reactor Trip Breakers, placing all the rods in a known position due to an inoperable DRPI system. All systems actuated as required and rods fully inserted.
Manual initiation of a reactor trip where the actuation is not part of a pre-planned evolution is reportable under 10 CFR 50.72 (b)(3)(iv)(A). While the reactor trip was initiated in accordance with the STP's instructions, the manual actuation was not a preplanned outcome of the STP. Subsequently, it was determined that rod B4 had remained on the bottom at Step 0 as indicated by DRPI. A moveable gripper fuse was blown, preventing that rod from being withdrawn. The blown fuse was replaced and testing continued in accordance with the procedure. There was no impact to public, employee, or plant safety. The NRC Resident Inspector was notified. |
| Where | |
|---|---|
Diablo Canyon  California (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+2.68 h0.112 days <br />0.016 weeks <br />0.00367 months <br />) | |
| Opened: | Russ Cruzen 19:11 May 30, 2016 |
| NRC Officer: | Jeff Herrera |
| Last Updated: | May 30, 2016 |
| 51965 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Shutdown (0 %) |
| After | Hot Shutdown (0 %) |
WEEKMONTHYEARENS 567692023-10-01T03:14:0001 October 2023 03:14:00
[Table view]10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip ENS 555262021-10-16T00:49:00016 October 2021 00:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip and Automatic Auxiliary Feedwater Actuation ENS 537642018-12-01T08:00:0001 December 2018 08:00:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Reactor Trip of Unit 2 Due to a Load Rejection ENS 519652016-05-30T16:30:00030 May 2016 16:30:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Opening of Reactor Trip Breakers Due to Rod Position Error Greater than 12 Steps ENS 505862014-11-01T00:40:0001 November 2014 00:40:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Automatic Emergency Diesel Generator Start Due to Loss of Offsite 230Kv Startup Power Supply ENS 497862014-02-02T19:29:0002 February 2014 19:29:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Automatic Reactor Trip ENS 492872013-08-16T01:24:00016 August 2013 01:24:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Startup Power Results in Valid Starts of All Three Emergency Diesel Generators ENS 491842013-07-10T16:50:00010 July 2013 16:50:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Automatic Reactor Trip ENS 491432013-06-24T04:20:00024 June 2013 04:20:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of 230 Kv Offsite Power Results in the Automatic Start of Emergency Diesel Generators ENS 487962013-03-01T05:54:0001 March 2013 05:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Bus Inadvertently De-Energized with Unit Defueled ENS 484002012-10-11T19:08:00011 October 2012 19:08:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Experienced an Automatic Reactor Trip on a 500Kv Line Differential Relay Actuation ENS 469002011-05-27T19:12:00027 May 2011 19:12:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Unit 1 Startup Power Results in Starting All Emergency Diesel Generators ENS 468942011-05-26T09:26:00026 May 2011 09:26:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Loss of Startup Power Due to Fault in Switchyard Causes All Edgs to Start ENS 468562011-05-17T16:54:00017 May 2011 16:54:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generators Start Due to Maintenance Activities ENS 467012011-03-26T21:49:00026 March 2011 21:49:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip When a Loss of the 2-1 Main Feedwater Pump Occurred ENS 445882008-10-22T03:51:00022 October 2008 03:51:00 10 CFR 50.72(b)(2)(xi), Notification to Government Agency or News Release, 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unit 2 Manual Reactor Trip Due to Jellyfish Intrusion ENS 444192008-08-17T07:12:00017 August 2008 07:12:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unusual Event Declared Due to Fire in Main Bank Tranformer ENS 433932007-05-29T05:50:00029 May 2007 05:50:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generator Actuation Due to Momentary Undervoltage Condition ENS 433912007-05-27T18:17:00027 May 2007 18:17:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Manual Reactor Trip in Mode 3 During Control Rod Testing ENS 433602007-05-12T17:25:00012 May 2007 17:25:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Emergency Diesel Generators Start Due to Loss of Off Site Start Up Power ENS 430472006-12-12T21:22:00012 December 2006 21:22:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Circulating Water Pump Failure Causes Explosion in Intake Structure ENS 430422006-12-11T00:08:00011 December 2006 00:08:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rapid Shutdown and Manual Reactor Trip Due to High Reactor Coolant Pump Stator Temperature ENS 421572005-11-19T23:51:00019 November 2005 23:51:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Diesel Generator Starts on a Vaild Bus Undervoltage Signal ENS 412502004-12-09T10:04:0009 December 2004 10:04:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Rps Actuation While Shutdown Due to Failed Fuse ENS 411682004-11-02T19:05:0002 November 2004 19:05:00 10 CFR 50.72(b)(3)(iv)(A), System Actuation Unplanned Diesel Generator Start on a Valid Bus Undervoltage Signal 2023-10-01T03:14:00 | |
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