Arkansas Nuclear One Unit 1 Fire and Explosion
Posted in the Brattleboro Forum
#1 Dec 9, 2013
There making junk yards out of all their plants.
#2 Dec 9, 2013
A resident in the vicinity of the Arkansas Nuclear One plant reported a "loud, ground shaking explosion and then saw smoke." It is believed that a transformer on site exploded, but the report remains unconfirmed at this time with Entergy and Arkansas Nuclear One officials.
The incident involved the plant's Unit 2 reactor. The Unit 1 reactor remained in service, furnishing electricity to the power grid, Entergy said.
The fire is the second incident at the nuclear power plant this year that has forced a sudden shutdown of the Unit 2 reactor. The same unit also automatically shut down on March 31 when a crane collapsed as it was moving a heavy piece of equipment out of a turbine building adjacent to Unit 2's nuclear island, which houses a reactor. After repairs, the Unit 2 reactor returned to service in late April.
The March accident resulted in one death and injuries to eight other contract workers who were at the site to assist with plant upgrades.
#3 Dec 9, 2013
Just as Entergy-ANO dropped the 600 ton stator that took out both nuke plant for months...I bet you it was another stupid employee mistake that destroyed this huge transformer.
Bet you it was a series of stupid employees that distroyed the transformer.
We are not sure if it is the main transformer or a axillary yet. It sounds like the main.
#5 Dec 9, 2013
Nov, 21 2013
#6 Dec 9, 2013
Bet you they were trouble shooting this or testing this transformer...flipped a switch and then they heard boom?
#7 Dec 9, 2013
Did they have a unrelatd trip and then the boom?
#8 Dec 9, 2013
On August 20, 2013, a switchyard walkdown by engineering revealed an undocumented wiring configuration associated with the ANO-2 Startup Transformer 3 (SU3)[FK][XFMR] voltage
regulator (VR)[RG] circuit. The SU3 VR functions to regulate the primary voltage of the
transformer and is required for operability of the transformer under certain offsite power
distribution conditions. The VR employs an automatic tapchanger controller (Beckwith model
M-0067E)[TTC] designed to automatically step taps to maintain the primary transformer voltage
within a pre-defined control band. The SU3 tapchanger controller has a time delay set at twenty
seconds to minimize excessive tapchanger cycles. This twenty second time delay is designed to
be bypassed for three minutes in the event of a Main Turbine Generator lockout , to allow
immediate SU3 voltage adjustments as ANO-2 station loads are fast transferred from the Unit
Auxiliary Transformer to the offsite SU3 Transformer during worst case accident load sequencing.
Engineering evaluation determined that the discovered wiring configuration of the SU3 VR
prevented the bypass of the twenty second time delay and potentially challenged some of the
assumptions made in the ANO-2 Millstone Study (Degraded Voltage) Calculations. SU3 was
declared inoperable on August 21, 2013 at 1718 CDT.
C. Event Cause
The apparent cause investigation determined that there were not enough known facts available
for this condition to accurately discern all applicable apparent or contributing causes; however,
it is believed that the wiring configuration on the SU3 voltage regulator was most likely
introduced in 2005-2006 during a switchyard improvement project by Entergy Arkansas
Transmission and Distribution, which was responsible for ownership of the subject VR at that
#9 Dec 9, 2013
So the thing today seeem the be the main transformer and this new LER is about trhe miss-wiring of the startup tranformer.
#10 Dec 10, 2013
So the started from the Aux transformer and the new LER is on the same transformer?
Was it snowing and icing out before this.
UNUSUAL EVENT DECLARED DUE TO UNIT 2 AUXILIARY TRANSFORMER EXPLOSION
"At approximately 0748 [CST] on 12/9/2013, an electrical fault occurred resulting in a fire and explosion on the ANO [Arkansas Nuclear One] Unit 2 Unit Auxiliary Transformer. This caused a unit trip and a loss of power to Startup 3 Transformer, which is one of the two offsite power feeds to ANO Unit 2. ANO Unit 2 is currently in a stable shutdown condition. With Startup 3 and Unit Aux Transformer unavailable, power was lost to the Reactor Coolant Pumps and Circulating Water Pumps. RCS [Reactor Coolant System] natural circulation is in progress removing core decay heat. Emergency Feedwater actuated due to low steam generator levels and is supplying both steam generators. The unit is steaming to the atmosphere. 2A-1 and 2A-3 are powered from SU [Startup] 2 Transformer. 2A-4 is powered from 2K-4B Emergency Diesel Generator.
#11 Dec 10, 2013
Beinning of the weekend.
Ice build up and melting with miss wiring, a fault that should have been protected...then the boom and shaking?
#12 Dec 10, 2013
Event began at 8 am and firing put out by mid morning....
#13 Dec 10, 2013
Doesn't sound like it's a big deal. Nothing to see here, move on!
#14 Dec 10, 2013
#15 Dec 10, 2013
You think so, there was a huge down draft in their stock price today?
#16 Dec 22, 2013
Happy Christmas ANO...you still down?
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