nuclear power plants and long term power outages

No coal plants here so they would have to leave them in the storage facility. So my family and I shouldn't have to hit the ground walking away from the area? They should be able to contain it without long term power. just basically shut down. So it seems mom was right and I was wrong. But I would much rather hunker her with my supplies than have to travel on the roads north with my children. That was going to be a huge deal getting them far enough away on foot.

If a nuclear reactor loses power it has to be shut down or melt down. To do this cadmium control rods are lowered in the core to stop the reaction. If there is no power from back up generator or batteries or the controls are not working then the rods have to lowered by manually. The persons that had to do that mostly would not live long afterwords, that would depend on any damage to the core and how close they had to get to shut it down. The US uses water cool reactors while some other countries (US subs and ships) use liquid sodium coolant which are said to be meltdown proof by some people.

en.wikipedia.org...

In a water cooled reactor if the coolant level gets low it will melt down or it could cause a steam flash which is what happened at the Russian reactor, Chernobyl.

en.wikipedia.org...

Some people think a nuclear reactor would go off like a A-bomb but that is not true. The worse one would do would be a Chernobyl type event but that is bad enough.

That's what I am thinking. People really wouldn't know it was happening until it was too late. I think ours is water cooled so That's why I feel it would eventually melt down because they would not be able to keep it cooled and the steam event would occur and the heat would build and eventually expose the rods and this would lead to the melt down. Again I am no expert that's why I posted it here to get everyone's opinion.

Originally posted by fixer1967
If a nuclear reactor loses power it has to be shut down or melt down. To do this cadmium control rods are lowered in the core to stop the reaction. If there is no power from back up generator or batteries or the controls are not working then the rods have to lowered by manually.

The rods don’t need electric power to drop. They will drop automatically if electric power is lost. The two ways to control them are electrical or hydraulic. On an electric system, they use a motor to lift them, and if the motor loses power, then the weight of the rod it’ self (plus spring loading) will cause it to drop back down. In a hydraulic system, there is hydraulic accumulators that will provide the power to push the rods back down by default if the electric control is lost.

The persons that had to do that mostly would not live long afterwords, that would depend on any damage to the core and how close they had to get to shut it down.

Why would that be? The control systems for the rods are on a working platform where people walk around all the time for regular system inspections.

www.dailyyonder.com...

It shows the people on a tour of the place and walking right in front (within a few feet) of the control cylinders that move the rods while the reactor is under full power.

The signs in front of the cylinders that control the control rods are there to indicate that there is possible surface contamination and it may be a good idea to use gloves when working with the stuff. It probably wouldn’t hurt you to do it with out gloves, but your hands may make a Geiger counter tick a bit until you washed them a few times.

That's pretty scary to live near one of those plants....but damn if you have to live near one, they should at least offer you free nuclear power so that is some benefit to you having to live near one.....i'm sure they could figure out a way to do that...if they wanted to

AFAIK an EMP only affects sensitive electronics and would not destroy or stop a running generator. The spark plugs are not going to melt or explode. That being said, lots of big generators are controlled by fancy computerized modules which may very well get zapped. Simple generators that are started by a pull rope or just a normal push-button start should be okay.

In the case of a nuclear power plant, I'm not sure if the plant itself can supply it's own local grid with power, but I do know there are failsafes that automatically lower the control rods if anything goes out of spec, thus stopping the reaction, so no meltdown or explosion.

Here is a quote from a person that has evidently worked at a nuke plant. It may calm your fears a bit……

greenspun.com...

it is an urban legend.
Cooling down (operating temperature to room temperature) requires no more than 3 days; I've regularly done it in less than 3 shifts.

Once cooled, the reactor (after about 4 days) is generating roughly 0.005% of its original heat. This amount of heat does require a small cooler, unless the top of the core is opened to atmosphere in the containment - as is usually done for normal refueling outages.

If the core cover is removed, the only thing needed is to periodically add clean water. No other power is needed, though all utilities are required by law to keep two alternate sources available.

The claims that backup power generators are unreliable (these have been repeatedly spread by a MA democratic congressman's office whose staffers hate and distruct nuclear power) are simply false. There is no other description nor excuse needed, these claims are simply wrong. Testing of these backup power supplies is also mandated in the operating license, and all plants regularly operate them.

I have found many quotes like that run along the same line, but that pretty much sums it up

That does make me feel a little better. In all my thought and preparation for whatever might(if anything) I just never thought about the nuclear plant and the problems that it might present. I pulled a map up of the plants throughout the states and there are so many. If problems do arise this would be a huge deal for thousands of people. I did not know there were so many. I see why lots of people say they would go away from the east coast because we have tons of them all around all the way up. I do feel this is very important that we as people know the danger if any that these would pose to us so if we needed to we could evacuate on our own. I am never waiting until someone else tells us to, because I feel by then it would already too late. Any one else want to add to this discussion???

reply to post by tinkytink1207


Here is a few sites that have pics of a couple reactors with their tops off for refueling.

www.corbisimages.com...

marketplace.veer.com...

www.gereports.com...

nuclearstreet.com...

I just wanted to revive my thread to see if anyone tonight might add new info to the questions I have asked. Thanks to everyone so far for all the links. I am still reviewing them and would appreciate any other input from others.

Originally posted by punctual
That's pretty scary to live near one of those plants....but damn if you have to live near one, they should at least offer you free nuclear power so that is some benefit to you having to live near one.....i'm sure they could figure out a way to do that...if they wanted to

I don't think they would be allowed to do that by law although I can't say for certain but in many towns surrounding nuke plants there are zero property taxes and other benefits. Wiscasset Maine is an example, when Maine Yankee Atomic Power Station was running there were no property taxes, they had a state of the art fire department, brand new schools etc. all from the huge tax revenue of the utility.

I just returned from a week-long school in Phoenix that was hosted by Arizona Public Service (APS), the primary owner and operator of the Palo Verde (PV) Nuclear Plant in southern AZ. One of the classes was on the emergency shut-down procedure for PV Nuke in the event there was a complete blackout of the Western grid. The information I received was specific to the PV plant, but I think it reasonable to expect their procedures and plans for a blackout are similar for nuke plants nation-wide. I'll just hit on the specific parts of the class as it relates to the OP of this thread.

As others in this thread have correctly noted, during a blackout of the grid, it's not difficult to stop the nuclear reaction. The real trick is dealing with the residual heat in the core and the reactor water. For this procedure a small amount of electrical power is needed (small relative to the megawatt output of the plant). There are redundant sources for this needed power. Each of the PV nukes (there are three separate units) have two enormous diesel generators dedicated specifically to providing shutdown power. These engines are started and tested regularly. They are started in pairs. That is to say there is one start button for the diesels for the PV unit #1, one start button for the diesels for the PV unit #2 etc. In the years since the plant was built they have never had a diesel fail to start. In the event of a blackout, the pair would be started and than one is immediately shut back off. Only one is needed per PV unit. In addition to the pair of diesel generators provided for each unit, there are two Combustion Turbine Generators that can be used to provide shutdown power for any of the three reactor units. That's a total of eight generators dedicated to providing shutdown power. There is enough diesel in underground storage to run three generators for one week. The instructor did not mention the run time that could be expected from the combustion turbines. What happens if none of the generators start? Per the instructor, each unit has battery bank capable of supplying 16 hours of emergency shutdown power.

The process for dealing with the residual heat in the core and the reactor water is simply to continue to make steam, but rather than using the steam to drive the turbine blades, the steam is released into the atmosphere. After doing this for a time the reactor and core are cooled. Remember, the reactor water and the water that is used to drive the steam turbine are two, separate, closed systems. science.howstuffworks.com... The steam released into the atmosphere is not reactor water.

Three Mile Island will give you an idea of the worst case scenario, which would require negligence or a lot of ignorance on the operators part.

TMI 2 took roughly two hours to melt down, which could have been avoided by simply adding water to the primary circuit in time. decay heat was the cause, btw, since the reactor was shut down immediately upon the loss of the outer coolant loop. if you're interested, you might want to take a look at the accident's timeline.


hyperphysics.phy-astr.gsu.edu...



i doubt EMP would affect components within the containment (steel shell and lots of reinforced concrete will shield a lot), which means emergency coolant at least is available. diesel engines without electronic injection will pretty much survive an EMP of any magnitude while it would take truly massive induced currents to destroy the generators.

interestingly, in 2006, a NPP in Forsmark, Sweden experienced scenario very similar to the one outlined in this thread, namely a total loss of power for 23 minutes without suffering any (published) damage, mainly because the automatic shutdown mechanism worked as advertised.

longer term is not a problem because the production of decay heat will have drastically dropped by then, which means you don't need any (convective) cooling after a day or so.

I started this thread way before the disaster we now face in Japan. I feel it is very weird how I was so worried about an emp pulse knocking out power and now we have the same thing with the earthquake and tsunami.
Going back over the responses I received at that time it is very interesting to see what the responses were back then from members. Most seemed to feel we had nothing to worry about.

I wonder if anyone would like to change their opinion based on current events?

reply to post by tinkytink1207


yes, the design at Fukushima had serious shortfalls, not just when it came to managing decay heat, but you'll have to admit that this scenario is worse than EMP alone, since salt water damages way more than just electronics and the tsunami itself may have blocked cooling inlets and disabled other equipment, which would have survived EMP (pipes, etc).

a long term power outage (the thread's original topic) would have vastly different results, because the plant would at least remain up and running until the fuel reserve is exhausted, at which point most of the decay heat would have already been dissipated.

Contrast this with Fukushima, emergency power supply for roughly an hour, then total loss of cooling through tsunami, combined with being suddenly and indefinitely cut off in the midst of a huge catastrophe, which itself was more damaging than an EMP attack alone would have been.

iow, we don't really know that much more about how NPPs would react to prolonged power loss or EMP, just how bad loss of cooling soon after shutdown can be in a poorly designed plant.

www.beyondnuclear.org...

this type doesn't have any containment, no matter what they say, the concrete refueling plug on top is especially noteworthy, since it's most likely just held in place by gravity. so much for 'safe' western-pattern reactors...

It is strange to see this thread back - we were discussing all of this in Janurary with no knowledge what so ever that something would happen as it has in Japan. I think the only thing I would change about my original postings would in regards to solar activity or solar flares - I did state that an M flare could take out electricity - would like to change that to possibly an X flare could do that but with the M flares we have had recently
we didn't have any problems. I remain anti nuclear for providing electricity. We are getting
very little information from the plant in Japan but when we do its never good news and sadly I think
it may get much worse. I feel so bad for those affected from the Earthquake, tsunami and now radiation. Good to see you back Tinytink!


I wish a Mod could tell me why my sentence structure is changing after I submit.

Backup system like sump pump backup generators are very important in case of power outage because they reduce the water damage in case of power outage. So, any backup generator has its importance in different situation.


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Sump pump backup

Fukushima was beyond a worst case scenario. It survived the earthquake, but not both. If it was just the earthquake they would have been able to shut it down safely. Nuclear reactor designs are as safe as can possibly be made. There are over 400 operating in the world, with another 60+ being built.

The first nuclear reactor was plugged in in 1954, in the Soviet Union (it ran four light bulbs), and since then, there have been two truly serious reactor accidents (Three Mile Island doesn't count, because that was over hyped by the media). This includes the plant that supplies North Alabama last year after the tornado outbreak, when the power grid was severely damaged, and Browns Ferry lost the incoming power and had to shut down. A number of plants have lost power over the years, and not one has gone into meltdown, or even come close to a dangerous situation because of it.