Earthquake/Tsunami in Japan

[Grall]

Assuming there was partial meltdown then those rods are pretty much stuck there.

Reactor 2 hasn't - or at least hadn't - melted, fully or even partially. There would have been time to get at least some of the fuel out of there, safing it from melting and polluting our planet.

Also, where would you put those rods so that they wouldn't cause any more pollution?

Same place they put rods during a re-fueling operation or maintenance work.

 

[Grall]

I saw in the previous blast a very clear ripple in the air that to me at least did suggest nitrogen feeding on oxygen in the air

That was shockwave lensing. Not sure why you think nitrogen would be involved in anything...? NOx:es only form at high temperatures, that steam cloud wouldn't be nearly hot enough.

 

[fellix]

Local residents watch how the ocean slowly demolishes their town:

http://www.liveleak.com/view?i=b5e_1300059825

 

[hoho]

Reactor 2 hasn't - or at least hadn't - melted, fully or even partially.

Are you sure? I'm pretty sure I've read reports about fuel rods not being submerged in there. While not submerged they will heat up until they start melting eventually.

Same place they put rods during a re-fueling operation or maintenance work.

Considering what kind of natural disasters those places have had to endure I'm not sure they even have the equipment working to do that right now.

 

[Grall]

I'm pretty sure I've read reports about fuel rods not being submerged in there.

Not read anything about them not being submerged, only that the water level in the core started dropping, post-2nd explosion.

Considering what kind of natural disasters those places have had to endure I'm not sure they even have the equipment working to do that right now.

Traverses and winches aren't complicated equipment.

 

[Gubbi]

Wondering why they don't just start pulling the fuel rods out of the core. If separated, the rate of radioactive decay - and hence heat output - should surely decrease by a lot.

The fission is completely halted. The problem is the heat developing from radioactive decay from the fuel and waste products themselves. This is on the order of 100-200MW and thus a non-trivial amount of heat to remove (but a lot less than the 3000MW normal operation point).

The situation seems very bad. They pump sea water into the reactor as an absolutely last resort since it kills the reactor for good. If they cannot cool the reactor the fuel+waste will slowly melt through the containment vessel. The melted fuel can itself reach a critical configuration even without water present to moderate, - then all kind of bad things will happen.

Cheers

 

[hoho]

The melted fuel can itself reach a critical configuration even without water present to moderate, - then all kind of bad things will happen.

If by that you are trying to say it could cause runaway chain reaction then you are massively underestimating how hard it really is to make nukes work

Though the thing can theoretically go up as a dirty bomb when something else explodes and spews radioactive fuel all over the place.

 

[Gubbi]

If by that you are trying to say it could cause runaway chain reaction then you are massively underestimating how hard it really is to make nukes work

I said critical, not super-critical . The thing won't go off as a bomb, but energy output could increase by several orders of magnitude and we would see a real meltdown.

Though the thing can theoretically go up as a dirty bomb when something else explodes and spews radioactive fuel all over the place.

This is clearly the main worry. The fuel is 6% MOX, so there will be short, medium and long lived radioactivity from iodine, cesium and plutonium respectively.

Cheers

 

[liolio]

That was shockwave lensing. Not sure why you think nitrogen would be involved in anything...? NOx:es only form at high temperatures, that steam cloud wouldn't be nearly hot enough.

I think he meant hydrogen which feed on oxygen burns/detonates and the result of the reaction is steam.

 

[liolio]

I'm not sure that at this stage we can't trust Japanese government in regard to the situation.
I'm crossing my fingers and praying for the best as Japenese already suffered many death without a nuclear disaster but the governement couldn't state the truth if things were to degenerate further. Tokio is +20millions inhabitants they don't have much solution to protect the population, panics or un'planned escape would only make things worse.

 

[Arwin]

I think he meant hydrogen which feed on oxygen burns/detonates and the result of the reaction is steam.

Sorry, yes, I did mean hydrogen.

 

[Grall]

With no disrespect intended towards all the victims of this horrific disaster or trying to make light of the events that have transpired and are ongoing:

Omg Xxx was right! The end of civilization is finally here!

 

[Kaotik]

The fuel rods in Dai-ichi reactor 2 are now fully exposed (to make sure that's not misunderstood, they're still within the reactor core, which is within the containement vessel - fully exposed means they're not surrounded by coolant (water) anymore)

 

[digitalwanderer]

The fuel rods in Dai-ichi reactor 2 are now fully exposed (to make sure that's not misunderstood, they're still within the reactor core, which is within the containement vessel - fully exposed means they're not surrounded by coolant (water) anymore)

That doesn't sound good...

 

[Squilliam]

That doesn't sound good...

Before this day I would have thought a wardrobe malfunction is indecent exposure, but today I find out that it's nothing in comparison to indecent fuel rod exposure in a nuclear power plant!

There was me thinking everything was under control and that it was being sorted... It seems crazy, why hasn't this been sorted? Surely they could have jerry rigged some sort of backup to the backup power for the coolent pumps or was that too late?

 

[Kaotik]

Before this day I would have thought a wardrobe malfunction is indecent exposure, but today I find out that it's nothing in comparison to indecent fuel rod exposure in a nuclear power plant!

There was me thinking everything was under control and that it was being sorted... It seems crazy, why hasn't this been sorted? Surely they could have jerry rigged some sort of backup to the backup power for the coolent pumps or was that too late?

That's one of the flaws in the dai-ichi plant at least, plugging outside powersource isn't that simple (they did get generator cars there quickly, but it's apparently not possible to plug them in)

But it's unlikely that the reactor 2 will cause anything worse than 1 & 3 already did, aka sure, there will be explosion, but no, the vessel won't break, it'll all stay within containment.

The plants have been under some criticism before for their lack of backup systems, but even with that, they still have backup system, backup system for the backup system and even backup system for that if my memory serves. The 9 magnitude earthquake & tsunami just rendered all of those useless or at least partially useless.

edit:
Great, now the diesel pumps are out of fuel, they're being refuelled but meanwhile the cooling stopped. Cores 1&3 rods completely exposed at least for a while, not sure if they've been (partially) re-submerged since.
Core 2 pumping malfunctioned, rods got fully exposed, but apparently this has been fixed since and 30cm of rods are submerged again.

 

[hoho]

Core 2 pumping malfunctioned, rods got fully exposed, but apparently this has been fixed since and 30cm of rods are submerged again.

From the information I've gathered over several past days the rods are around 3m in length. Having only 10% of that submerged doesn't really help all that much.

 

[Grall]

If those rods are actually exposed to nothing but air, and dissipate on the order of 100MW or more of heat, then surely they would light up like lightbulb filaments and melt within minutes, if not seconds. There must have been some form of cooling of those rods, like water spraying/evaporating off of them, even if they weren't actually submerged...

 

[Arwin]

Thinks are not looking good at any rate, a partial meltdown seems to have happened at least, and there are also warnings that another big earthquake could strike within a few days.

http://www.bbc.co.uk/news/world-asia-pacific-12733393

 

[cjo]

If those rods are actually exposed to nothing but air, and dissipate on the order of 100MW or more of heat, then surely they would light up like lightbulb filaments and melt within minutes, if not seconds. There must have been some form of cooling of those rods, like water spraying/evaporating off of them, even if they weren't actually submerged...

The wikipedia article on meltdown suggests about a 0.3K - 1K rise in temperature per second if the cores are exposed in a steam environment, possibly in reference to the specific design at Three Mile Island.