Palisades

[Higgs]

Anyone at Palisades? Can someone shed some light on what really has gone on there recently? Lots of misinformation on the interwebs.

[kalvin1]

Another shutdown at Palisades nuclear power plant
By AP  | September 26, 2011

COVERT TOWNSHIP, Mich. (AP) — The Palisades Nuclear Plant in southwestern Michigan has shut down five days after restarting from an earlier shutdown.

Operators of the southwestern Michigan plant say the plant shut down automatically from full power about 3:10 p.m. Sunday because of an electrical breaker fault.

New Orleans-based Entergy Corp. owns Palisades and says no one was hurt in the shutdown. Entergy says plant personnel are evaluating the problem and working toward "a repair and restoration schedule."

Palisades is in Van Buren County's Covert Township, about 55 miles southwest of Grand Rapids. It was shut down Sept. 16 because of a loss of water in a cooling system, then brought back on the grid last Tuesday.

The U.S. Nuclear Regulatory Commission inspected the plant in August after a water pump component failed.

COVERT TOWNSHIP, Mich. (AP) — The Palisades Nuclear Plant in southwestern Michigan has shut down five days after restarting from an earlier shutdown.

Operators of the southwestern Michigan plant say the plant shut down automatically from full power about 3:10 p.m. Sunday because of an electrical breaker fault.

New Orleans-based Entergy Corp. owns Palisades and says no one was hurt in the shutdown. Entergy says plant personnel are evaluating the problem and working toward "a repair and restoration schedule."

Palisades is in Van Buren County's Covert Township, about 55 miles southwest of Grand Rapids. It was shut down Sept. 16 because of a loss of water in a cooling system, then brought back on the grid last Tuesday.

The U.S. Nuclear Regulatory Commission inspected the plant in August after a water pump component failed.

         
         
            
     
         



             

   
 

   

[Higgs]

Right. Thanks. I read what is out there.

Anyone on the inside?

[Higgs]

I guess I should be more specific.

Some NRC "spokesperson" supposedly said that they were venting radioactive steam out the "atmospheric steam dumps" after the last shutdown. Now, I only just got done with my PWR systems, and I am not licensed on one yet, but from what I remember (last week) we don't vent radioactive steam out our atmospheric steam dumps.

Granted, most of those sources are your tin foil hat wearing types, but I'm just gathering evidence before I start refuting at the couple of tin foil hat wearing websites I visit.

Justin

[Fermi2]

"At 1506 EDT, while the electricians were working on the left train DC bus, a bus bar slipped causing an arc and a loss of the left train DC busses D-10 L and D-10 R. This resulted in the loss of two preferred AC [120 Volt Instrument] busses Y-10 and Y-30. The loss of both preferred AC busses caused a reactor trip, a safety injection signal, auxiliary feedwater actuation signal, containment high radiation isolation signal, and main steam isolation signal.

"All systems responded as expected. Electric power has been restored to the affected DC busses and preferred AC busses. The plant is stable in Mode 3 at NOT and NOP, and controlling temperature using Atmospheric Dump Valves. Pressurizer level is high due to the loss of letdown (result of containment isolation signal), however, it is recovering slowly."

All rods fully inserted and the electrical lineup is back to normal.

[Higgs]

That is what I figured, erroneous reporting. I googled the name of the NRC rep, and it appears these "anti nuke" sites have taken two different quotes of hers out of context and put them together to make her say that they were venting radioactive steam. Lame.

[wingnut]

The plant hasn't had the best of luck this summer. Wonder if they'll get the same attention that Browns Ferry is getting?

[thenuttyneutron]

The loss of both preferred AC busses caused a reactor trip, a safety injection signal, auxiliary feedwater actuation signal, containment high radiation isolation signal, and main steam isolation signal.

OUCH! This sounds like a typical annual requal exam on the simulator.  Mode 3 without the condenser is not fun.  Holy Crap!  Was DSS (Diverse Scram System) the only Safety System that they did not light off?

I would not want to be in the group of people that caused the loss of the vital buses.  I bet they are on pins and needles now.

[Fermi2]

OUCH! This sounds like a typical annual requal exam on the simulator.  Mode 3 without the condenser is not fun.  Holy Crap!  Was DSS (Diverse Scram System) the only Safety System that they did not light off?

I would not want to be in the group of people that caused the loss of the vital buses.  I bet they are on pins and needles now.

Mode 3 without the main condenser in a Westinghouse or CE reactor isn't all that bad. I've been there a few times. Heck we heat up with the MSIV closed and don't open them until NOT.

WTH is a DSS?

[thenuttyneutron]

Mode 3 without the main condenser in a Westinghouse or CE reactor isn't all that bad. I've been there a few times. Heck we heat up with the MSIV closed and don't open them until NOT.

WTH is a DSS?

DSS is a modification to the CE and B&W plants.  It is an energize to trip system to back up RPS for ATWS events.

http://www.nrc.gov/reading-rm/doc-collections/cfr/part050/part050-0062.html

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1780/sr1780.pdf (scroll to page xiii)

It looks like the Westinghouse designs don't need it because they maintain a more negative MTC.

[Fermi2]

We don't maintain it, it just happens. We do have AMSAC which isn't a back up scram system. It trips the turbine and starts the Aux Feedpumps during an ATWS.

[Fermi2]

Fortunately this event "only" scrammed the reactor.  It could have been much worse.

HU Error Prevention Tools?  Who needs 'em?

Why did it happen?

Electricians failed to properly insulate all other exposed sections of bus prior to removing the section of bus bar that required removal per their maintenance as discussed in their pre-job brief. This decision was made in the field without supervisor concurrence. While removing the section of bus bar, the electrician lost control after being startled by what he perceived as a small arc. When he lost control, the section of bus bar was loose enough to rotate and make contact with a section of bus bar below, causing the short. Had the insulation been placed in the panel as discussed in the pre-job brief, the short would not have occurred.

Incorrect, while I see the point it more than scrammed the reactor. It caused a containment isolation and removed the condenser as a heat sink. It isolated letdown and due to the SI prevented the Pressurizer heaters from functioning therefore Palisades lost the normal means of RCS Pressure control.
It caused an inadvertent SI and on a plant Palisades age that is a more than serious concern due to potential PTS issues.

So no it wasn't just a only scrammed the reactor.