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ENS 53793
Show incoming properties
Category
ENS Notification  and Power Reactor
CFR
10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation +  and 10 CFR 50.72(b)(3)(iv)(A), System Actuation +
Current power
0  +
Current reactor mode
Hot Standby +
Description
On December 18, 2018 at 1126 CST, Arkansas … On December 18, 2018 at 1126 CST, Arkansas Nuclear One, Unit 1 (ANO-1) reactor automatically tripped due to a loss of the A-1, non-vital 4160V bus. All control rods fully inserted. Loss of the A-1 bus resulted in de-energizing A-3 vital 4160V bus. Emergency Diesel Generator #1, K-4A, started automatically and is currently powering A-3 vital bus. Non-vital buses A-2, H-1, and H-2 and vital bus A-4 transferred power automatically to the Startup Transformer #1. Off-site power remains energized and available for ANO-1. The reason for loss of A-1 bus is unknown at this time. Currently, ANO-1 has stabilized in Mode 3, Hot Standby.</br>Decay heat is being removed by the main condenser using the turbine bypass valves. The loss of the A-1, non-vital bus, is under investigation. The licensee has notified the NRC Resident Inspector and the state. the NRC Resident Inspector and the state.  +
Discovered date
06:00:00, 18 December 2018  +
ENS id number
53,793  +
Emergency class
Non Emergency +
Entered date
15:40:00, 18 December 2018  +
Event date
06:00:00, 18 December 2018  +
Event description
On December 18, 2018 at 1126 CST, Arkansas … On December 18, 2018 at 1126 CST, Arkansas Nuclear One, Unit 1 (ANO-1) reactor automatically tripped due to a loss of the A-1, non-vital 4160V bus. All control rods fully inserted. Loss of the A-1 bus resulted in de-energizing A-3 vital 4160V bus. Emergency Diesel Generator #1, K-4A, started automatically and is currently powering A-3 vital bus. Non-vital buses A-2, H-1, and H-2 and vital bus A-4 transferred power automatically to the Startup Transformer #1. Off-site power remains energized and available for ANO-1. The reason for loss of A-1 bus is unknown at this time. Currently, ANO-1 has stabilized in Mode 3, Hot Standby.</br>Decay heat is being removed by the main condenser using the turbine bypass valves. The loss of the A-1, non-vital bus, is under investigation. The licensee has notified the NRC Resident Inspector and the state. the NRC Resident Inspector and the state.  +
Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +, ENS 53793 +  and ENS 53793 +
Initial power
100  +
Initial reactor mode
Power Operation +
LER
05000313/LER-2018-004-01, Reactor Trip Due to the Loss of a Non-Vital 4160 Volt Bus +, 05000313/LER-2018-004, Reactor Trip Due to the Loss of a Non-Vital 4160 Volt Bus +  and Reactor Trip Due to the Loss of a Non-Vital 4160 Volt Bus +
Last update date
00:00:00, 18 December 2018  +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
12:30:09, 19 December 2018  +
NRC officer
Dong Park +
Notification date
15:40:00, 18 December 2018  +
Originated by
Sean Davis +
Reactor critical
true  +
Region
NRC Region 4 +
Reporting criterion
10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation +  and 10 CFR 50.72(b)(3)(iv)(A), System Actuation +
Reporting time
0.403 d (9.67 hours, 0.0576 weeks, 0.0132 months)  +
Scram
Automatic Scram +
Site
Arkansas Nuclear +
Start date
06:00:00, 18 December 2018  +
State
Arkansas +
System
Emergency Diesel Generator +, Main Condenser +  and Control Rod +
Title
Automatic Reactor Trip - Loss of Non-Vital Bus  +
Turbine component
Turbine bypass valve +
URL"URL" is a <a href="/Special:Types/URL" title="Special:Types/URL">type</a> and predefined property provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a> to represent URI/URL values.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20181219en.html#en53793  +
Unit
1  +
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