Japan shook with 8.8 Quake and Hit By Tsunami

treitz3

cheddar wrote: »

Pretty bad joke to make. It's quite possible these people have been exposed to levels of radiation that could cause harm to them including damage to their skin and that they could eventually get doses that prove fatal.

The 28 people that stayed behind at Chernobyl all died within 3 months.

JustinHEMI

megasat16 wrote: »

Believe neither at this time. It's speculation again and not facts. All I wanted to say is that finger pointing has now begun.

Justin, what are the chances of total meltdown and containment breach in case of the fuel rods total exposure without water?

The cores are contained and cooled at this point.

Units 1, 2 and 3 are "out of the woods," so to speak. Unit 2 does have a containment breach, but it has been confirmed to be in the torus... AKA suppression pool. Although not ideal, containment would still hold a molten core if it came to that.

That covers the recently operating cores.


The issue now is the spent fuel pool at unit 4.

I agree with the NRC chairmen... if it has been without cooling since the quake, it is dry by now. In that case, the fuel in that pool is melting, or will be. Although that core has been offloaded since November, there is still a tremendous amount of energy stored in that spent fuel. With no cooling mechanism, the time to boil that pool would have been measured in days, if not hours.

Like Cheddar mentioned, the spent fuel pools are open to atmosphere... no containment like the core itself.

I am waiting for more updates from other colleagues, but last I heard, they may be having some limited success at getting some water back onto that fuel.

Justin

JustinHEMI

Here is a graphic to help you better understand what I am talking about. This containment design is identical to mine.

Justin

megasat16

Thanks Justin for the picture depiction of what is going on with the spent fuel in Reactor 4.

I always thought the spent fuel rods are loaded into the steel barrels, locked shut, air sucked out, filled with inert gases and stored in the chiller / cooler on the same site as the reactor...

http://www.nrc.gov/waste/spent-fuel-storage/pools.html

megasat16

JustinHEMI wrote: »

The cores are contained and cooled at this point.

Units 1, 2 and 3 are "out of the woods," so to speak. Unit 2 does have a containment breach, but it has been confirmed to be in the torus... AKA suppression pool. Although not ideal, containment would still hold a molten core if it came to that.

That covers the recently operating cores.


The issue now is the spent fuel pool at unit 4.

I agree with the NRC chairmen... if it has been without cooling since the quake, it is dry by now. In that case, the fuel in that pool is melting, or will be. Although that core has been offloaded since November, there is still a tremendous amount of energy stored in that spent fuel. With no cooling mechanism, the time to boil that pool would have been measured in days, if not hours.

Like Cheddar mentioned, the spent fuel pools are open to atmosphere... no containment like the core itself.

I am waiting for more updates from other colleagues, but last I heard, they may be having some limited success at getting some water back onto that fuel.

Justin

Justin,

Let's assume the NRC chief and you are right and the spent fuel pool is totally dried out and the spent fuel rods are all melted away.

Could it compromise the containment field around reactor cores and creating additional havoc for the live fuel rods inside the reactor? Or it won't likely happen coz the spent fuel may not have enough radiation to breach the containment field of the reactor nearby?

ben62670

These things should be built below ground, or have very strong containment walls built higher than the structure itself so they can just flood the whole reactor if something goes bad. At least have it setup so that the spent fuel and the fuel in use can be dropped into a containment "pool"

JustinHEMI

megasat16 wrote: »

Thanks Justin for the picture depiction of what is going on with the spent fuel in Reactor 4.

I always thought the spent fuel rods are loaded into the steel barrels, locked shut, air sucked out, filled with inert gases and stored in the chiller / cooler on the same site as the reactor...

http://www.nrc.gov/waste/spent-fuel-storage/pools.html

Some are... really old ones. For example, at Peach Bottom.. we have dry cask storage. But that is only for fuel that has cooled in the pool for 15 years or more. Only after that long of a time, can the fuel be stored in dry casks. That still doesn't eliminate the need for cooling. The dry casks use natural air circulation to keep the fuel cool.

Oh, and it is stored on site. The government has failed to provide a central facility for safe storage of spent fuel, as they promises.

I am hoping one good change comes from this for us... opening Yucca Mountain. That still will not eliminate the need for spent fuel pools, however.

Justin

cheddar

megasat16 wrote: »

Justin,

Let's assume the NRC chief and you are right and the spent fuel pool is totally dried out and the spent fuel rods are all melted away.

Could it compromise the containment field around reactor cores and creating additional havoc for the live fuel rods inside the reactor? Or it won't likely happen coz the spent fuel may not have enough radiation to breach the containment field of the reactor nearby?

I don't think you realize the gravity of those spent fuel pools. They still are basically the core of a reactor with the fuel seperated and encased to prevent nuclear reaction. But they still contain a lot of the nasty stuff you don't want released into the environment and you don't want them to melt down any more than you would an operational core. The problem is that these pools don't have any containment around them and are open to the atmosphere meaning they have even less protection than an operational core in the containment structure. If those helicopters are dropping water on the reactor buildings, they're probably trying desperately to recover the fuel in those open pools through holes in the building created by previous explosions. And I read that they're dropping on unit 3. So it could be they are having problems in the spent fuel pools of more than just unit 4.

JustinHEMI

megasat16 wrote: »

Justin,

Let's assume the NRC chief and you are right and the spent fuel pool is totally dried out and the spent fuel rods are all melted away.

Could it compromise the containment field around reactor cores and creating additional havoc for the live fuel rods inside the reactor? Or it won't likely happen coz the spent fuel may not have enough radiation to breach the containment field of the reactor nearby?

No it won't breach the reactor's containment. I know that drawing looks like it could, but it won't.

Justin

JustinHEMI

ben62670 wrote: »

These things should be built below ground, or have very strong containment walls built higher than the structure itself so they can just flood the whole reactor if something goes bad. At least have it setup so that the spent fuel and the fuel in use can be dropped into a containment "pool"

The containment is below ground, for the most part. If the core somehow made it through its vessel and the steel containment, it would hit the concrete liner... which sits on bed rock.

Spent fuel pools were never meant to be permanent, long term storage. But when the NIMBYs shut down Yucca mountain... there was no other choice.

Justin

schwarcw

Justin,

Does that design have the six reactor recirc pumps like Oyster Creek? I've been inside Oyster Creek, but that's been about 20 years ago. I don't remember much except those six pumps. It's easy to figure why GE went to the two reactor recirc pumps with the jet pumps between the shroud and the inside of the vessel instead of all those pumps.

I've been a Westinghouse PWR guy for over 30 years. I always wondered why GE put those control blades in from the bottom? The GE design I thought was interesting because it actually could perform a "load-follow" operation. Although, the economics of that would never play out and as you know all Nuc powered reactors are always run at full power.

My days in engineering are long gone. I've been buying equipment for the 4 AP1000 plants were building in China, and the four US plants in Georgia and SC. These passive plants can shut down and come to a cold shutdown passively. Of course this is not the preferred method!:biggrin:

cheddar

cheddar wrote: »

I read that they're dropping on unit 3. So it could be they are having problems in the spent fuel pools of more than just unit 4.

Yep, both unit 3 and 4 in this report:

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300322727P.pdf

More red boxes on this thing every day...

megasat16

cheddar wrote: »

I don't think you realize the gravity of those spent fuel pools. They still are basically the core of a reactor with the fuel seperated and encased to prevent nuclear reaction. But they still contain a lot of the nasty stuff you don't want released into the environment and you don't want them to melt down any more than you would an operational core. The problem is that these pools don't have any containment around them and are open to the atmosphere meaning they have even less protection than an operational core in the containment structure. If those helicopters are dropping water on the reactor buildings, they're probably trying desperately to recover the fuel in those open pools through holes in the building created by previous explosions. And I read that they're dropping on unit 3. So it could be they are having problems in the spent fuel pools of more than just unit 4.

You made a Good Point! I actually understood the situation with the spent fuel thus the question. As dangerous threat as the spent fuel pool poses due to meltdown and radiation it emits, it's lesser evil compared to what would coming out of the ones inside the reactor.

If they can pump enough water to the spent fuel pool or recover them somehow, radiation levels should drop significantly soon.

JustinHEMI wrote: »

No it won't breach the reactor's containment. I know that drawing looks like it could, but it won't.

Justin

Thanks for the answer! As long as what's inside doesn't come out, I guess the Japanese have a chance of containing it.

JustinHEMI

schwarcw wrote: »

Justin,

Does that design have the six reactor recirc pumps like Oyster Creek? I've been inside Oyster Creek, but that's been about 20 years ago. I don't remember much except those six pumps. It's easy to figure why GE went to the two reactor recirc pumps with the jet pumps between the shroud and the inside of the vessel instead of all those pumps.

I've been a Westinghouse PWR guy for over 30 years. I always wondered why GE put those control blades in from the bottom? The GE design I thought was interesting because it actually could perform a "load-follow" operation. Although, the economics of that would never play out and as you know all Nuc powered reactors are always run at full power.

My days in engineering are long gone. I've been buying equipment for the 4 AP1000 plants were building in China, and the four US plants in Georgia and SC. These passive plants can shut down and come to a cold shutdown passively. Of course this is not the preferred method!:biggrin:

I am going to be a Westinghouse PWR guy myself... going for my license at Beaver Valley.

Anyway, they are mostly BWR-4s with Mark I containments... identical to Peach Bottom... so they will have 2 jet pumps. I am not sure of the 3s/5s mixed in there. Probably the same.

Blades go in from bottom so steam can go out the top.

I wanted to go work at Vogtle, because I would love to operate a 21st century nuke plant, but they didn't want to pay my price.

Justin

JustinHEMI

megasat16 wrote: »

You made a Good Point! I actually understood the situation with the spent fuel thus the question. As dangerous threat as the spent fuel pool poses due to meltdown and radiation it emits, it's lesser evil compared to what would coming out of the ones inside the reactor.

If they can pump enough water to the spent fuel pool or recover them somehow, radiation levels should drop significantly soon.



Thanks for the answer! As long as what's inside doesn't come out, I guess the Japanese have a chance of containing it.

I am still cautiously optimistic, that this isn't going to turn into some monstrous disaster like Chernobyl. The active cores are in relatively good shape, compared to a few days ago.

The spent fuel situation, while bad, should be able to be contained as soon as they restore some power... which I heard will be by tomorrow.

Justin

Tour2ma

JustinHEMI wrote: »

The containment is below ground, for the most part. If the core somehow made it through its vessel and the steel containment, it would hit the concrete liner... which sits on bed rock.

The fuel rods melt around 2800 deg C... yes?

If the core made it through the steel (melt point 1600 C or less depending on grade), then I have my doubts about the concrete (which substantially sublimes at around 1000 C).

I understand the bedrock underpinning, but rock melts, too... most under 1200 C. But if groundwater is present (likely given the Ocean proximity), then I'd guess fracking will likely be the greater concern.

Justin,

A couple more questions if you have a moment... sorry if I missed any earlier discussion.

Going back to the beginning... how would Operations be certain that the shutdowns were successful? Could a greater than design quake have either displaced or "misaligned" the (boron?) control rods?

If a cluster of fuel rods melted, are their control rods then no longer in play for sure?

Is a melted uranium mass more or less active than the fuel rods?

JustinHEMI

Tour2ma wrote: »

The fuel rods melt around 2800 deg C... yes?

If the core made it through the steel (melt point 1600 C or less depending on grade), then I have my doubts about the concrete (which substantially sublimes at around 1000 C).

I understand the bedrock underpinning, but rock melts, too... most under 1200 C. But if groundwater is present (likely given the Ocean proximity), then I'd guess fracking will likely be the greater concern.

Justin,

A couple more questions if you have a moment... sorry if I missed any earlier discussion.

Going back to the beginning... how would Operations be certain that the shutdowns were successful? Could a greater than design quake have either displaced or "misaligned" the (boron?) control rods?

If a cluster of fuel rods melted, are their control rods then no longer in play for sure?

Is a melted uranium mass more or less active than the fuel rods?

Yeah the whole "china syndrome." Naw, that isn't what will happen. The steel used is specially formulated to contain a molten core... albeit not indefinitely. Same with the concrete. It is designed to contain it long enough to flood it.

That will have known the shutdowns were successful by looking at their nuclear instruments and control rod position indicators.

Before they lost all power, the reactors automatically shut down on seismic activity. During that time, the first immediate actions of an operator are to verify all rods going in and power lowering.

Even after they lost power, there would still have been enough instrumentation being supplied by batteries and diesels to verify this. They didn't lose the diesels and batteries until well into the disaster.

As for a melted mass, I think you are asking me if it will fission? No, it won't. In our reactors, there is a very specific critical array required. Besides, they have been pumping boron in with the water to ensure it remains shutdown. The control rods are also boron and it would be expected that they would melt and mix with the fuel anyway. There is no real concern for a fission even in these reactors, unlike Chernobyl.

Justin

JustinHEMI

I just learned some good news.

It turns out not the entire core of unit 4 was not in that pool and it is likely that the fuel that is in there isn't melting because it is old and cool enough to survive without water.

Lets keep up our hope and prayers. I don't have a confirmation link yet because this was just texted to me by a friend that works for a certain agency.
Justin

cheddar

Any good news is welcome. Especially since CNN reported the helicopter drops didn't go well. I think only 1 out of 4 hit their target or something like that.

cheddar

They've also got water cannon riot trucks on the way to try to get water in from a distance. But I guess one thing about building reactors in such isolated conditions is that when things go bad, it's really hard to get resources to them to fix the problems. The coast of Fukushima really is isolated, even from the rest of the prefecture with small roads and limited ways of getting in and out.

Tokyo probably had all the resources needed to get the plant's systems up quickly including easy access to power, large portable generators, even these water cannon trucks. But it's just too far away from all that infrastructure when days and hours matter so much after a nuke plant disaster.

mrbigbluelight

JustinHEMI wrote: »

The energy of the gamma radiation fields they are in would require a lead suit so heavy, that no human could possibly wear it.
The suits they wear now, are to protect them from contamination.
Think of it like this...
Imagine a pile of dog crap. The crap itself is contamination, the radiation is the smell. Justin

Thanks for making that analogy, Justin.

Particularly in light of news reports that one hears.

" We here at station KBTHD have been assured by authorities that the radiation from the Japanese nuclear plants will have no affect upon inhabitants of the West coast".

Well, technically that's true.
Unless you have a 1 million Curie source mounted on a 500 foot tower, yes, you won't receive any radiation.

BUT: you get a 1 Billion Curie source who's primary and secondary containment is breached, and steam/hydrogen explosions now have ejected contamination into the air stream, then welcome to the party, no matter where you are.
The actual radiation you receive from a small inhalation of air may be small.
BUT: you get just a small particle of plutonium ( an 'alpha' emitter ) inside your lungs and it causes tremendous damage/death.
Alpha particles can be stopped with a sheet of paper; inside the lungs, an alpha particle is stopped by the .... well .... lungs. And there's the trouble.

Lead is actually a pretty crappy shielding material .
Water is a lot better.
I think the numbers are: a 1/10 thickness for lead is 10 feet.
a 1/10 thickness for water is 1" inch.

JustinHEMI

mrbigbluelight wrote: »

Thanks for making that analogy, Justin.

Particularly in light of news reports that one hears.

" We here at station KBTHD have been assured by authorities that the radiation from the Japanese nuclear plants will have no affect upon inhabitants of the West coast".

Well, technically that's true.
Unless you have a 1 million Curie source mounted on a 500 foot tower, yes, you won't receive any radiation.

BUT: you get a 1 Billion Curie source who's primary and secondary containment is breached, and steam/hydrogen explosions now have ejected contamination into the air stream, then welcome to the party, no matter where you are.
The actual radiation you receive from a small inhalation of air may be small.
BUT: you get just a small particle of plutonium ( an 'alpha' emitter ) inside your lungs and it causes tremendous damage/death.
Alpha particles can be stopped with a sheet of paper; inside the lungs, an alpha particle is stopped by the .... well .... lungs. And there's the trouble.

Lead is actually a pretty crappy shielding material .
Water is a lot better.
I think the numbers are: a 1/10 thickness for lead is 10 feet.
a 1/10 thickness for water is 1" inch.

It depends on the radiation.

Water won't stop gamma's, only lead and steel will.

Water stops neutrons. That is what the numbers you used allude to. That is another reason we use water as a moderator. Another good shield is polyethelene.. for neutrons.

Paper stops alphas.

Your clothes stops betas.

cheddar

Well, here it comes. Been looking at the models and it looks like the plume will hit the west coast (will hit Alaskan islands earlier) Friday morning. Seems to be in a tight band going to the south but scooting by (missing) Hawaii. So southern California followed by Nevada, Utah, and Arizona. Keep hearing that negative conseqeunces should be very low. Whatever that means. Based on some probability model, no doubt. Still, even in Arizona or thereabouts, the model showed relative radiation exposure .1-.01 from whatever they were comparing it to at the source.

JustinHEMI

cheddar wrote: »

Well, here it comes. Been looking at the models and it looks like the plume will hit the west coast (will hit Alaskan islands earlier) Friday morning. Seems to be in a tight band going to the south but scooting by (missing) Hawaii. So southern California followed by Nevada, Utah, and Arizona. Keep hearing that negative conseqeunces should be very low. Whatever that means. Based on some probability model, no doubt. Still, even in Arizona or thereabouts, the model showed relative radiation exposure .1-.01 from whatever they were comparing it to at the source.

In other words... a negligible increase above background.

You are probably doing more damage to your brain by talking on your cell phone.

Justin

cheddar

Here's the link:

http://www.nytimes.com/interactive/2011/03/16/science/plume-graphic.html?ref=science

cheddar

JustinHEMI wrote: »

In other words... a negligible increase above background.

You are probably doing more damage to your brain by talking on your cell phone.

Justin

Just don't like the choice of words. Why can't they just say, there will be no negative consequences? What's a very low consequence? A slight chance of a slight increase in ... ?

Erik Tracy

deleted

JustinHEMI

cheddar wrote: »

Just don't like the choice of words. Why can't they just say, there will be no negative consequences? What's a very low consequence? A slight chance of a slight increase in ... ?

I say it is of no consequence. .01 is minimum detectable. .1 compared to your normal daily exposure from nature is nothing.

BUT... I am NOT a Rad Health expert.... but I have been doing nuclear power since 1998.

Justin

cheddar

These are not absolute levels, they are relative levels to whatever is being experienced in Japan. Based, I would guess on predicted wind dispersal patterns. So those blue areas on the graphic could be exposure at .1 times whatever the Japanese are getting, if I'm reading this correctly.

BTW, what is the maximum level a nuke plant is allowed to expose a non-worker to in a year? What is a 'safe' level of exposure in a year? Some reports use milliseiverts, some microseiverts, and I'm not sure that the reporters aren't getting the measures confused.

stuwee

I'm ready for it [IMG][/img]