After the apocalypse ??

[Highlander]

.... but if all the reactors failed at the same time, then the amount of radioactive cloud would circle the globe and come right back at you with your in-coming wind

[bigpaul]

(25 April 2013, 14:41)Highlander Wrote: .... but if all the reactors failed at the same time, then the amount of radioactive cloud would circle the globe and come right back at you with your in-coming wind

well thats what worries me, i've just looked up the chart i had and it was a nuclear STRIKE rather than a nuclear melt down...anyway i'm probably far enough away, we have most of Somerset and EXMOOR in between, its the radioactive dust that worries me although as i said the prevailing wind is away from me, but what happens if it stays in the atmosphere-maybe it forms part of the jetstream or something like that??

[I-K-E]

(25 April 2013, 14:08)Tartar Horde Wrote:

(25 April 2013, 13:13)bigpaul Wrote:

(25 April 2013, 10:01)Tartar Horde Wrote: To be honest BP there won't be anyone around to see this happen in UK, all the Nuclear power stations will melt down in a serious crash and flood britain with levels of radiation that will kill most of the life here, leaving it an irradiated wasteland for the next twenty thousand years. any total collapse of the infrastructure is a death sentence for us here as we can't escape the contamination. Chernobyl was bad enough with one reactor going critical, imagine what it would be like with all the uk reactors going critical, we are talking an extinction event for the british Isles that will take eons to heal.

yeah but that is a nuclear accident, what happens if its just no one around to work them-do they just shut down or do they melt down?

They will all melt down BP. If the electric goes off they will run on back up generators that will keep the Fuel Rod coolant tank water cold and moving. Once the back up stops the water will stop being cooled surrounding the fuel rods, and it will boil off exposing the fuel rods to the air, the fuel rods will burn at thousands of degrees spewing out lethal doses of radiation into surrounding area and atmosphere. This will happen at all nuclear power plants if the power stops the cooling pumps.
You just have to look at the distribution of them, and use the Chernobyl model to plot the area of effect one nuclear plant can have, and do that for a map of the UK for every nuclear plant. The results will frighten the FCK out of you mate.

not sure about this .... surely if the power went out to a nuclear reactor the back up generator will power the safety systems to make the reactor safe until the power comes back on such as lowering the control rods to halt the nuclear chain reaction.

And the new reactors that will be coming online in a few years are designed to have passive safety features that can cope if a total melt down too

[Highlander]

I dont know either, but I cant believe that there is not some sort of safety built into these things in case the power goes off permanently,... they must plan for terrorist strikes or even EMPs

[bigpaul]

yeah but how long does the backup system work for before it packs up too? then what happens? what if the power NEVER comes back on?? i thought these things were made so they just shut down in an emergency!

[Tartar Horde]

The control rods need to be cooled by the water surrounding them, even if they are retracted they remain highly radioactive, but they are still surrounded by water to cool them. The back up systems all work off Diesel/petrol etc in the case of a total electrical breakdown to make electricity to power the pumps for the cooling system to work. If no one comes to top the fuel tanks up the generators will run out of fuel and stop, therefore stopping the water pump systems from maintaining a cool enough temperature to stop the fuel rods melting the building. This is what happened in Fukashima, once coolant pressure was lost nothing could stop the reactor from going critical. The Documentary about life after humans have vanished shows the very scenario I am talking about. I will try to get link for it folks.

[I-K-E]

(25 April 2013, 15:03)bigpaul Wrote: yeah but how long does the backup system work for before it packs up too? then what happens? what if the power NEVER comes back on?? i thought these things were made so they just shut down in an emergency!

once the rods are down they stay down until the main power comes back on.

If it doesn't come back on well the control rods stay there

nobody want another Chernobyl and have built or added systems to reactors to take this into account. Hell the vitrified high level waste is stored in a build the use natural convection to cool the waste and needs no mechanical cooling here in the uk

The main issue to me would be many years down the line post SHTF and that would be leaks due to failing infrastructure but that would be decades after an event

[Tartar Horde]

The reason all nuclear plants will fail in a total breakdown of civilisation,, is that TPTB never assume they won't be able to get the situation under control, they always assume the fuel will get there to stop any emergency-Fukashima shows they are not prepared for a total breakdown of the system.

[I-K-E]

(25 April 2013, 15:08)Tartar Horde Wrote: The control rods need to be cooled by the water surrounding them, even if they are retracted they remain highly radioactive, but they are still surrounded by water to cool them. The back up systems all work off Diesel/petrol etc in the case of a total electrical breakdown to make electricity to power the pumps for the cooling system to work. If no one comes to top the fuel tanks up the generators will run out of fuel and stop, therefore stopping the water pump systems from maintaining a cool enough temperature to stop the fuel rods melting the building. This is what happened in Fukashima, once coolant pressure was lost nothing could stop the reactor from going critical. The Documentary about life after humans have vanished shows the very scenario I am talking about. I will try to get link for it folks.

yes but the back up system failed at Fukashima went the back up generator got flooded by the tsunami coming over the top of the wall

in a power down situation the back up generator would kick lower the control rods and keep pumping water until the reactor core is cooled and I'm sure that there would be more than enough fuel for the genny to do this.

with the control rods down the nuclear chain reaction stops but the core is still hot .... think of a boiling kettle that still hot just after it switches off but that cool over time due to air cooling.... In a reactor the same will happen due to water being pumped around but once it is cold it not going to heat up again until the control rods are raised and the pumps are back on (and lot's of other things too)... with your kettle the water will only get hot again if you switch it back on

back up safety systems will put the reactor in to a safe statue in the shortest possible time if the power grid goes down and this is all done using back up generators. Depending on the weather in winter in the uk just this last year we've seen places with no power for days due to the weather taking down power lines

[Tartar Horde]

Here's the link to the vid

https://www.youtube.com/watch?v=8iUqd9XiQxc