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ENS 47624
Show incoming properties
Category
ENS Notification  and Power Reactor
Area
Switchyard +
CFR
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 +, 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown +, 10 CFR 50.72#b3vD +  and 10 CFR 50.72#c1iii +
Current power
0  +
Current reactor mode
Hot Standby +
Description
At 1101 EST, Byron Unit-2 experienced a re … At 1101 EST, Byron Unit-2 experienced a reactor trip due to RCP undervoltage. All rods fully inserted, MSIV's were manually closed and decay heat is being removed by Auxiliary Feedwater pumps running and steam leaving via atmospheric relief valves. The unit is currently in a natural circulation cooldown with the diesels supplying station emergency loads. Licensee will be cooling the plant down to Mode 5.</br>At 1118 EST, Byron declared an Unusual Event due to a loss of offsite power on Unit 2 from a faulted Station Auxiliary Transformer (SAT). The faulted SAT caused both 6.9 kV and 4.1 kV bus voltage to drop. Smoke was observed coming from the SAT with no visible flames being apparent. This caused bus loads to trip without a complete loss of ESF busses 241 and 242. These buses were manually disconnected from the SAT, which transferred the load to the emergency diesel generators 2A and 2B. Both diesel generators started and loaded without incident. Offsite assistance was requested from the local fire department as a precaution. </br>The licensee is also declaring notification for 10 CFR 50.72(b)(3)(v)(D) </br>Unit 1 is not being affected by this event and remains at 100% power.</br>The licensee has notified the NRC Resident Inspector.</br>* * UPDATE FROM GREG BALESTRIERI TO JOHN KNOKE AT 2119 EST ON 01/31/12 * *</br>At 2000 CST on 1/31/12, Byron terminated their Unusual Event due to the Loss of Offsite Power to Unit 2. Switchyard repairs were completed and offsite power has been restored to essential busses 241 and 242 thru System Auxiliary Transformers 242-1 and 242-2. Unit 2 Emergency Diesel Generators have been shutdown.</br>The licensee is citing classification 10 CFR 50.72(c)(1)(iii) </br>The licensee has notified the NRC Resident Inspector. Notified R3DO (James Cameron), NRR EO (Louise Lund), IRD MOC (Scott Morris), DHS (Konopka) and FEMA (Hollis). Licensee may issue a press release.lis). Licensee may issue a press release.  +
Discovered date
16:01:00, 30 January 2012  +
ENS id number
47,624  +
Emergency class
Unusual Event +
Entered date
11:39:00, 30 January 2012  +
Equipment trip
Reactor Trip +
Event date
16:01:00, 30 January 2012  +
Event description
At 1101 EST, Byron Unit-2 experienced a re … At 1101 EST, Byron Unit-2 experienced a reactor trip due to RCP undervoltage. All rods fully inserted, MSIV's were manually closed and decay heat is being removed by Auxiliary Feedwater pumps running and steam leaving via atmospheric relief valves. The unit is currently in a natural circulation cooldown with the diesels supplying station emergency loads. Licensee will be cooling the plant down to Mode 5.</br>At 1118 EST, Byron declared an Unusual Event due to a loss of offsite power on Unit 2 from a faulted Station Auxiliary Transformer (SAT). The faulted SAT caused both 6.9 kV and 4.1 kV bus voltage to drop. Smoke was observed coming from the SAT with no visible flames being apparent. This caused bus loads to trip without a complete loss of ESF busses 241 and 242. These buses were manually disconnected from the SAT, which transferred the load to the emergency diesel generators 2A and 2B. Both diesel generators started and loaded without incident. Offsite assistance was requested from the local fire department as a precaution. </br>The licensee is also declaring notification for 10 CFR 50.72(b)(3)(v)(D) </br>Unit 1 is not being affected by this event and remains at 100% power.</br>The licensee has notified the NRC Resident Inspector.</br>* * UPDATE FROM GREG BALESTRIERI TO JOHN KNOKE AT 2119 EST ON 01/31/12 * *</br>At 2000 CST on 1/31/12, Byron terminated their Unusual Event due to the Loss of Offsite Power to Unit 2. Switchyard repairs were completed and offsite power has been restored to essential busses 241 and 242 thru System Auxiliary Transformers 242-1 and 242-2. Unit 2 Emergency Diesel Generators have been shutdown.</br>The licensee is citing classification 10 CFR 50.72(c)(1)(iii) </br>The licensee has notified the NRC Resident Inspector. Notified R3DO (James Cameron), NRR EO (Louise Lund), IRD MOC (Scott Morris), DHS (Konopka) and FEMA (Hollis). Licensee may issue a press release.lis). Licensee may issue a press release.  +
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ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +, ENS 47624 +  and ENS 47624 +
Initial power
100  +
Initial reactor mode
Power Operation +
Last update date
00:00:00, 31 January 2012  +
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>.
02:04:57, 2 March 2018  +
NRC officer
John Knoke +
Notification date
11:39:00, 30 January 2012  +
Originated by
Leo Wehner +
Person
John Knoke +, Louise Lund +  and Scott Morris +
Reactor critical
true  +
Reactor type
Westinghouse PWR 4-Loop +
Region
NRC Region 3 +
Reporting criterion
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 +  and 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown +
Reporting time
-0.182 d (-4.37 hours, -0.026 weeks, -0.00599 months)  +
Site
Byron +
Start date
16:01:00, 30 January 2012  +
State
Illinois +
System
Emergency Diesel Generator +  and Auxiliary Feedwater +
Title
Unusual Event Due to Loss of Offsite Power Greater than 15 Minutes  +
Topic
Loss of Offsite Power +
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.
http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2012/20120201en.html#en47624  +
Unit
2  +
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