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Japan hit by 9.0 earthquake.

Re: Japan hit by 8.9 earthquake.

It's pond 4 isn't it? That's the one with the plutonium. I remember reading a couple of days ago that it is a more dangerous fuel than uranium, as it finds criticality with much greater ease, or something like that.

And unlike a reactor core, the cooling pond doesn't have much in the way of containment.
 
Re: Japan hit by 8.9 earthquake.

Jadzia said:
It's pond 4 isn't it? That's the one with the plutonium. I remember reading a couple of days ago that it is a more dangerous fuel than uranium, as it finds criticality with much greater ease, or something like that.
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Higher neutron multiplicity I guess.

And unlike a reactor core, the cooling pond doesn't have much in the way of containment.
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From the pictures I've seen when the plant was operating normally, there was no cover to the pond other than the roof of the reactor building.
 
Re: Japan hit by 8.9 earthquake.

Wouldn't it make more sense to be filling these things with boric acid entirely rather than water?
 
Re: Japan hit by 8.9 earthquake.

Apparently, they don't have enough boric acid to do anything like that, they've had to import half of South Korea's supply just to keep doing what they're doing.
 
Re: Japan hit by 8.9 earthquake.

TheGodBen said:
Apparently, they don't have enough boric acid to do anything like that, they've had to import half of South Korea's supply just to keep doing what they're doing.
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I have some in my cupboard. Perhaps I could send it over :p

Asbo Zaprudder said:
You'd think, given that the water is going to thermalise the neutrons and act as a moderator.
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In the link you posted earlier Asbo, someone was wondering if the plant operators used water from pond 4 to help cool the problem reactors.

If that was boronated, it's understandable why they'd chose to use that if they're short of boric acid.

Now if at the same time, they've kept the pool replenished with plain water, then there's going to be dilution, and then would be understandable why activity in the pool would be increasing.

~~~
Even though these are all thermal reactors, #4 uses MOX fuel (Pu + U) . I'm sure that MOX fuel is used in some fast neutron reactors too. Can that affect the physics of the pool water? ie. with respect to boron content, temperature, and change of water (moderator) density if it is boiling? :shrug:
 
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Re: Japan hit by 8.9 earthquake.

Jadzia said:
In the link you posted Asbo, someone was wondering if the plant operators used water from pond 4 to help cool the problem reactors.

If that was boronated, it's understandable why they'd chose to use that if they're short of boric acid.

Now if at the same time, they've kept the pool replenished with plain water, then there's going to be dilution, and then would be understandable why activity in the pool would be increasing.

Even though these are all thermal reactors, #4 uses MOX fuel (Pu + U) . I'm sure that MOX fuel is used in some fast neutron reactors too. Can that affect the physics of the pool water? ie. with respect to boron content, temperature, and change of water (moderator) density if it is boiling? :shrug:
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If there's less boron, there's less neutron capture. Boron also has a higher cross section for slow (thermal) neutrons than fast ones so the presence of water (or similar suitable moderator) to thermalize the neutrons helps (http://en.wikipedia.org/wiki/Boron#Enriched_boron_.28boron-10.29) .

If the rods became partially exposed due to a change in water level or voids in the boiling water, the fast neutrons would escape more easily from rods in the centre of the pool and I guess might be captured in the outer-lying rods initiating more fission producing more neutrons.

I used to have access to FORTRAN code from the IAEA that could calculate what would happen in these sorts of scenarios, but that was a long time ago. My trying to predict exactly what's going to happen by guess work is doomed to failure. So :shrug: from me as well.
 
Re: Japan hit by 8.9 earthquake.

Jadzia said:
It's pond 4 isn't it? That's the one with the plutonium. I remember reading a couple of days ago that it is a more dangerous fuel than uranium
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I think it's the fourth one, but it has both, not just plutonium so it's extra safe. :rolleyes:

South Korea is supposed to be sending in an insane amount of boron, like 50 tons or something. At this point I'd suggest evacuate the whole damn area and just set up a small nuke to take out the damn power plant.
 
Re: Japan hit by 8.9 earthquake.

I read earlier today something that surprised me.

If -- hypothetically -- all of the fuel at Fukushima-I were to burn and become airborne, there would be 1000 times as much radioactivity in the fallout than what was created by the weapons used against Japan in 1945.

I never realised fission plants used that much of the stuff.
 
Re: Japan hit by 8.9 earthquake.

I read an article the other day that said if thorium was used instead of plutonium or uranium nuclear power plants would be much safer. Does anyone know if this is so?
 
Re: Japan hit by 8.9 earthquake.

Jadzia said:
I read earlier today something that surprised me.

If -- hypothetically -- all of the fuel at Fukushima-I were to burn and become airborne, there would be 1000 times as much radioactivity in the fallout than what was created by the weapons used against Japan in 1945.

I never realised fission plants used that much of the stuff.
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150 tonnes or thereabouts of fuel typically per reactor.
 
Re: Japan hit by 8.9 earthquake.

J. Allen said:
Jadzia, Holy schnikes, it's a bit of a mess. It seems like #2 is the one being scrutinized the most. Here's hoping for a positive change there.

Goji said:
Well, I am quite nervous now about my future and my proximity to this power plant, about 120 miles away. My parents are freaking me out more, bombarding me with emails urging me to drop everything and come home. Which is not something I can do, but we are looking into me leaving earlier than planned. It's a real nightmare. I'm no longer as calm and collected about it as I once was.
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You're a remarkably intelligent and resourceful man, Goji. I've no doubt you'll get through this.
Stay safe and I know things will work out.
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WE ARE ALL DOOMED.

In all seriousness, I am most worried about the children I teach. It scares me that they have to stay here and be exposed to something that could do long term damage. I am not convinced that the levels as they are now are dangerous, but if they become so, they (unlike myself) will have nowhere to go. I hope they will be safe.

As for myself, I am leaving the country this Saturday. Not because I am afraid of the situation as it is now, but I am nervous that it could get worse at any moment and make it that much more difficult to leave. If I were intent on staying here long term, I would tough it out. But I am leaving anyway, and since all my classes are canceled now, there is no real reason for me to risk waiting. Which is sad. I had wanted to spend time exploring and hanging out with my friends. Even if I stay, that isn't really possible. Oh well.
 
Re: Japan hit by 8.9 earthquake.

Latest report from JAIF

jaif17march1600.png

"The International Atomic Energy Association (IAEA) said that the reactor 4 cooling pool has trebled in temperature while those for reactors 5 and 6 have more than doubled."
link



Goji said:
In all seriousness, I am most worried about the children I teach. It scares me that they have to stay here and be exposed to something that could do long term damage. I am not convinced that the levels as they are now are dangerous, but if they become so, they (unlike myself) will have nowhere to go. I hope they will be safe.
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From various bits I've read on the net, I've put this radiation guide together.

With 1 sievert a person will suffer internal hemorrhaging, with a 10% risk of developing a fatal cancer soon after. It's about what the people of Hiroshima were given in 1945.

A 0.1 sievert dose is enough to cause radiation sickness and loss of appetite, and is correlated with significant risk of cancers later in life. This is in the order of what you get in a lifetime if exposed to only normal background radiation. This is the threshold of what is potentially deadly toxic. Very urgent priority to escape or shelter.

A 0.01 sievert is what you get from a CT scan. As a single dose, it's unlikely to cause any sickness or loss of appetite, but it is still a big dose of radiation that you don't want to have unless you really need it. This is what you get per day if radiation levels are "1000 times normal". Leave with haste.

0.001 sievert (1 millisievert) is not going to have noticable effects as a single dose. This is what you get per day if radiation levels are "100 times normal". This is sometimes cited as the danger threshold. If you live and work in these conditions for several months, having this dose every day, there's some risk that it would affect health or reduce life expectancy.

A 0.0001 sievert (0.1 millisievert) dose is "low level radiation". Even if you live and work constantly in these conditions your whole life, this may not adversely affect you... or it might. This is what you'd get per day if radiation levels are "10 times normal". It's also what you get from a transatlantic flight. Airline crew limit their airtime because this is considered a minor risk to health if it happens on a daily basis for several years.

A 0.00001 sievert (0.01 millisievert) dose is the normal dose you get from background radiation per day. There are greater risks to your health than this level of radiation.
 
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