Reactor meltdown possible in Japan.

[Dunkman]

Looking at the videos of the 2 explosions at the Daichi plant, they keep saying the explosions did not damage the reactor shells, and I'm finding that hard to believe. Yes, the blast was forced upwards, blowing the top of the building(s) off. But wouldn't the back-end intensity of the explosion also damage to the reactor shell as well? How thick is the containment vessel? Can it actually take an explosive impact, without being cracked or breached?

It's designed to withstand a direct impact from a 747, so I'm gonna go with yes.

[janetjanet998]

If that is the case, that they will be periodically releasing radioactive(and the general public will not care about amount..they will just see RADIOACTIVE)steam into the atmosphere(especially if it is to the point that it is can be detected on ships 100 miles away) for a considerable time period(months to up to a year)....

..then who the hell is going to want to travel or do business in or near that area(including Tokyo)? They can say all they want about 'it all blowing out to sea' and all that, but people are going to still think 'what if it is blown north or south or east by some unusual erratic winds or something' and are just going to want to avoid the area. There are reports online now of people in Tokyo not wanting to go outside because of this. What long term effect is this going to have with the recovery, business, visitors, etc. to the larger surround ing area, including Tokyo? How is this Japanese economy going to be hit by this over the months?

.. just makes one wonder. The last thing they need is the long term scare and hype of having 'periodic radioactive releases'. As can be seen in this thread, just the idea of anything 'radioactive' scares the **** out of a lot of people.

more from the article linked

But all weekend, after a series of intense interchanges between Tokyo and Washington and the arrival of the first American nuclear experts in Japan, officials said they were beginning to get a clearer picture of what went wrong over the past three days. And as one senior official put it, “under the best scenarios, this isn’t going to end anytime soon.”

also

-------------

They have apparently tried used firefighting equipment — hardly the usual procedure. But forcing the seawater inside the containment vessel has been difficult because the pressure in the vessel has become so great.

One American official likened the process to “trying to pour water into an inflated balloon,” and said that on Sunday it was “not clear how much water they are getting in, or whether they are covering the cores.”

The problem was compounded because gauges in the reactor seemed to have been damaged in the earthquake or tsunami, making it impossible to know just how much water is in the core.

When the fuel was intact, the steam they were releasing had only modest amounts of radioactive material, in a nontroublesome form. With damaged fuel, that steam is getting dirtier.

And workers at the pumping operation are presumed to be exposed to radiation; several workers, according to Japanese reports, have been treated for radiation poisoning

[Dunkman]

Here is a Wall Street Journal Article this morning:

WSJ Article

A good read on the issue

It is a read on the subject. I am just completely amazed that it seems impossible to find an unbiased assessment of what is happening there. If I had to bet, I'd say that guy is probably right about the lasting consequences, but the last paragraph of the article just destroys any credibility he had built up.

[Bodhi Cove]

In the US, the main containment structure is meant to at least withstand the impact of a passenger aircraft.

Thank you.

[OSUmetstud]

Here is a Wall Street Journal Article this morning:

WSJ Article

A good read on the issue

The article definitely appears to have some bias...given the author's book.

Is this true?:

If the coolant continues to evaporate, the water level can fall below the level of the fuel rods, exposing them. This will cause a meltdown, meaning the fuel rods melt to the bottom of the steel pressure vessel.

Early speculation was that in a case like this the fuel might continue melting right through the steel and perhaps even through the concrete containment structure—the so-called China syndrome, where the fuel would melt all the way to China. But Three Mile Island proved this doesn't happen. The melted fuel rods simply aren't hot enough to melt steel or concrete.

[janetjanet998]

The article definitely appears to have some bias...given the author's book.

Is this true?:

If the coolant continues to evaporate, the water level can fall below the level of the fuel rods, exposing them. This will cause a meltdown, meaning the fuel rods melt to the bottom of the steel pressure vessel.

Early speculation was that in a case like this the fuel might continue melting right through the steel and perhaps even through the concrete containment structure—the so-called China syndrome, where the fuel would melt all the way to China. But Three Mile Island proved this doesn't happen. The melted fuel rods simply aren't hot enough to melt steel or concrete.

"normal" Steel melts around 2500f I'm not sure about concrete

other experts over the weekend said the rods can get hotter then 2000..i think 2-4K one said

[Ed Lizard]

A reactor stays hot after a reactor scram. A scram is the rapid insertion of control rods, often made of hafnium, which has multiple isotopes that have a high cross section for neutron absorbtion. Google 'Barnes".

A moment after the scram, the reactor is still making 7% of the average power it was making the previous few days because of the decay of radioactive fission products. This declines in an exponential fashion. This heat is called "decay heat".

A fission reaction shouldn't be likely unless the fuel rods melt faster than the control rods (they'd be hotter, but I don't know the melting temps of a complex material with zirconium cladding and uranium embedded in a niobium matrix versus hafnium control rods) and uranium can pool together.

Bur a shut down reactor will generate significant heat for days after a shutdown.

[ArtRosen]

So we've had 2 and most likely a possible 3rd partial meltdown. The shell of the building that houses reactor #2 hasn't exploded yet, but I think we can all guess that it most likely will if present conditions persist. Whether something was designed to withstand an impact of a passenger plane or not, does not mean that it actually has. We hope all of the containment units have held together.. but a US helicopter spotted radiation 60 km outside of the zone, which is 3x the evacuation zone, meaning people who were not told to evacuate have been exposed to radiation and now a US carrier crew has been exposed to heavy radiation (a month's worth in an hour). While this isn't chernobyl, this is definitely a situation in which areas surrounding the plant can be exposed to radiation... and we see that they already have. My hope is that these people get treated and there is no long term health effects from the exposure to radiation.

[SuperNET]

It's a guess but I believe you will see some suicide workers (if we have not already) lining up to help out the country in it's time of need. Chances are that most of the workers have been contaminated to a level that will affect the health of the individual.

[ArtRosen]

It's a guess but I believe you will see some suicide workers (if we have not already) lining up to help out the country in it's time of need. Chances are that most of the workers have been contaminated to a level that will affect the health of the individual.

Right now - it's difficult to believe anything coming out of the government's mouth. They told us everything was fine in reactor #3 around this time yesterday. 12 hours later, the roof literally is blown off of the reactor. That doesn't happen when things are fine.

[OSUmetstud]

It's a guess but I believe you will see some suicide workers (if we have not already) lining up to help out the country in it's time of need. Chances are that most of the workers have been contaminated to a level that will affect the health of the individual.

u think so? The highest I heard was 1000 times normal in the control room...which is only about 300 mrem. That's equivalent to a little more than a chest X-ray.

[Mello]

So we've had 2 and most likely a possible 3rd partial meltdown. The shell of the building that houses reactor #2 hasn't exploded yet, but I think we can all guess that it most likely will if present conditions persist. Whether something was designed to withstand an impact of a passenger plane or not, does not mean that it actually has. We hope all of the containment units have held together.. but a US helicopter spotted radiation 60 km outside of the zone, which is 3x the evacuation zone, meaning people who were not told to evacuate have been exposed to radiation and now a US carrier crew has been exposed to heavy radiation (a month's worth in an hour). While this isn't chernobyl, this is definitely a situation in which areas surrounding the plant can be exposed to radiation... and we see that they already have. My hope is that these people get treated and there is no long term health effects from the exposure to radiation.

Your post is meaningless without details.

"Whether something was designed to withstand an impact of a passenger plane or not, does not mean that it actually has."

Anything's possible if you believe.

"We hope all of the containment units have held together.. but a US helicopter spotted radiation 60 km outside of the zone"

How much radiation? Every single one of us is exposed to radiation every day. Just very small amounts. It takes a whole lot more to have any meaningful effects.

[mappy]

Right now - it's difficult to believe anything coming out of the government's mouth. They told us everything was fine in reactor #3 around this time yesterday. 12 hours later, the roof literally is blown off of the reactor. That doesn't happen when things are fine.

Thank goodness we have you to set the record straight. How many nuclear meltdowns have there been again, I've lost track.

[janetjanet998]

Right now - it's difficult to believe anything coming out of the government's mouth. They told us everything was fine in reactor #3 around this time yesterday. 12 hours later, the roof literally is blown off of the reactor. That doesn't happen when things are fine.

from late last night

0650: Japan's government is insisting that radiation levels across the country are safe, says the BBC's Chris Hogg in Tokyo, but a German businessman has told our correspondent that some foreign firms are starting to move their expatriate staff south - or out of the country altogether - because they don't have confidence in what the government is saying any more.

[OSUmetstud]

So we've had 2 and most likely a possible 3rd partial meltdown. The shell of the building that houses reactor #2 hasn't exploded yet, but I think we can all guess that it most likely will if present conditions persist. Whether something was designed to withstand an impact of a passenger plane or not, does not mean that it actually has. We hope all of the containment units have held together.. but a US helicopter spotted radiation 60 km outside of the zone, which is 3x the evacuation zone, meaning people who were not told to evacuate have been exposed to radiation and now a US carrier crew has been exposed to heavy radiation (a month's worth in an hour). While this isn't chernobyl, this is definitely a situation in which areas surrounding the plant can be exposed to radiation... and we see that they already have. My hope is that these people get treated and there is no long term health effects from the exposure to radiation.

30 mrem in an hour is not heavy radiation...it's an 1/8th of a chest x-ray.

[SuperNET]

u think so? The highest I heard was 1000 times normal in the control room...which is only about 300 mrem. That's equivalent to a little more than a chest X-ray.

The 7th fleet operating 100 miles away moved as a result of contamination of both people and helicopters.

[OSUmetstud]

The 7th fleet operating 100 miles away moved as a result of contamination of both people and helicopters.

Right...but if they were only receiving a month's worth of radiation in an hour..that's like 30 mrem...which isn't much. I guess radiation levels could be higher than the government is reporting...but I'd rather not speculate.

[janetjanet998]

1426: Mr Goto says his greatest fear is that blasts at number 3 and number 1 reactors may have damaged the steel casing of the containment vessel designed to stop radioactive material escaping into the atmosphere. More to follow.

>1422: Japanese engineer Masashi Goto, who helped design the containment vessel for Fukushima's reactor core, says the design was not enough to withstand earthquakes or tsunamis and the plant's builders, Toshiba, knew this. More on Mr Goto's remarks to follow.

[sojitodd]

30 mrem in an hour is not heavy radiation...it's an 1/8th of a chest x-ray.

But much of what will happen, regarding what people do, the choices that the public, business, etc. make will not be based on scientific fact, but on perception-and as can be seen in this thread, phrases like 'heavy radiation' are going to have an impact. For every time someone says 'heavy radiation', there will need to be ten other people immediately following with an explanation like yours for the general public to 'get it', imo.

*on the other hand, I should add that I do not at all expect the Japanese govt. to be 'open and forthcoming' with valid and timely information, especially given their track record.

[ThePhotoGuy]

BBC:

1431: More from Japanese nuclear engineer Masashi Goto: He say that as the reactor uses mox (mixed oxide) fuel, the melting point is lower than that of conventional fuel. Should a meltdown and an explosion occur, he says, plutonium could be spread over an area up to twice as far as estimated for a conventional nuclear fuel explosion. The next 24 hours are critical, he says.

http://www.bbc.co.uk...e-east-12307698

[janetjanet998]

one thing that concerns me is how fast the goverment said last night "there was no damage to the containment building" very soon after the #3 explosion.

well if it has a steel casing around it like MR Goto is saying then there is NO way they would know if it that casing was fine so fast. NO WAY

when you look for damage to steel you use non destructive tetsing such as Ultrasonic and magnetic particle testing to look for cracks on the surface and internal

that is a slow process that is done by hand and would take many many hours to do correctly . Plus who is their right mind would want to do them there at this time

[ThePhotoGuy]

Tests detected low levels of radioactivity on 17 U.S. Navy helicopter crew members when they returned to the USS Ronald Reagan after conducting disaster relief missions in Japan, the military said Monday.

http://www.cnn.com/2011/WORLD/asiapcf/03/14/japan.us.navy.radiation/index.html?hpt=T1

[Mello]

one thing that concerns me is how fast the goverment said last night "there was no damage to the containment building" very soon after the #3 explosion.

well if it has a steel casing around it like MR Goto is saying then there is NO way they would know if it that casing was fine so fast. NO WAY

when you look for damage to steel you use non destructive tetsing such as Ultrasonic and magnetic particle testing to look for cracks on the surface and internal

that is a slow process that is done by hand and would take many many hours to do correctly

Wouldn't gamma radiation leak through any crack no matter how small and be easily detected?

[janetjanet998]

Wouldn't gamma radiation leak through any crack no matter how small and be easily detected?

i don't know..but good point

[99lsfm2]

Dr. Masters this AM:

Radiation from Japan's stricken Fukushima Daiichi nuclear plant has been detected 100 miles to the northeast, over the Pacific Ocean, by the U.S. military. Westerly to southwesterly winds have predominated over Japan the past few days, carrying most of the radiation eastwards out to sea. The latest forecast for Sendai, Japan, located about 40 miles north of the Fukushima nuclear plant, calls for winds with a westerly component to dominate for the remainder of the week, with the exception of a 6-hour period on Tuesday. Thus, any radiation released by the nuclear plant will primarily affect Japan or blow out to sea. A good tool to predict the radiation cloud's path is NOAA's HYSPLIT trajectory model. The model uses the GFS model's winds to track the movement of a hypothetical release of a substance into the atmosphere. One can specify the altitude of the release as well as the location, and follow the trajectory for up to two weeks. However, given the highly chaotic nature of the atmosphere's winds, trajectories beyond about 3 days have huge uncertainties.One can get only a general idea of where a plume is headed beyond 3 days. I've been performing a number of runs of HYSPLIT over past few days, and so far great majority of these runs have taken plumes of radioactivity emitted from Japan's east coast eastwards over the Pacific, with the plumes staying over water for at least 5 days. Some of the plumes move over eastern Siberia, Alaska, Canada, the U.S., and Mexico in 5 - 7 days. Such a long time spent over water will mean that the vast majority of the radioactive particles will settle out of the atmosphere or get caught up in precipitation and rained out. It is highly unlikely that any radiation capable of causing harm to people will be left in atmosphere after seven days and 2000+ miles of travel distance. Even the Chernobyl nuclear disaster, which had a far more serious release of radioactivity, was unable to spread significant contamination more than about 1000 miles.

http://www.wunderground.com/blog/JeffMasters/article.html

[Bodhi Cove]

Per : http://allthingsnucl...ushima-reactors

One particular concern with Unit 3 is the presence of mixed-oxide (MOX) fuel in the core. MOX is a mixture of plutonium and uranium oxides. In September 2010, 32 fuel assemblies containing MOX fuel were loaded into this reactor. This is about 6% of the core.

I have done considerable analysis on the safety risks associated with using MOX fuel in light-water reactors. The use of MOX generally increases the consequences of severe accidents in which large amounts of radioactive gas and aerosol are released compared to the same accident in a reactor using non-MOX fuel, because MOX fuel contains greater amounts of plutonium and other actinides, such as americium and curium, which have high radio-toxicities.

Because of this, the number of latent cancer fatalities resulting from an accident could increase by as much as a factor of five for a full core of MOX fuel compared to the same accident with no MOX. Fortunately, as noted above, the fraction of the fuel in this reactor that is MOX is small. Even so, I would estimate this could cause a roughly 10% increase in latent cancer fatalities if there were a severe accident with core melt and containment breach, which has not happened at this point and hopefully will not.

While the authorities continue playing down the possibility of a breach of the primary containment at these reactors, I remain concerned. Fukushima Dai-Ichi reactor Units 1, 2, and 3 are boiling water reactors with Mark I containments. The Mark I is unusually vulnerable to containment failure in the event of a core-melt accident. A recent study by Sandia National Laboratories shows that the likelihood of containment failure in this case is nearly 42% (see Table 4-7 on page 97). The most likely failure scenario involves the molten fuel burning through the reactor vessel, spilling onto the containment floor, and spreading until it contacts and breeches the steel containment-vessel wall.

The Sandia report characterizes these probabilities as “quite high.” It’s not straightforward to interpret these results in the context of the very complicated and uncertain situation at Fukushima. But they are a clear indication of a worrisome vulnerability of the Mark I containment should the core completely melt and escape the reactor vessel.

I attempted to make sense of the study noted above, but it is WAY over my head. Maybe some of the brain trust here (who have been exceptionally educational thus far) can make sense of it and enlighten the rest of us.

See page 95 through 97

http://www.nrc.gov/r...6920/cr6920.pdf

[ArtRosen]

30 mrem in an hour is not heavy radiation...it's an 1/8th of a chest x-ray.

http://www.nytimes.com/2011/03/14/world/asia/14plume.html

The Pentagon was expected to announce that the aircraft carrier Ronald Reagan, which is sailing in the Pacific, passed through a radioactive cloud from stricken nuclear reactors in Japan, causing crew members on deck to receive a month’s worth of radiation in about an hour, government officials said Sunday.

[janetjanet998]

http://www.nytimes.c...ia/14plume.html

The Pentagon was expected to announce that the aircraft carrier Ronald Reagan, which is sailing in the Pacific, passed through a radioactive cloud from stricken nuclear reactors in Japan, causing crew members on deck to receive a month’s worth of radiation in about an hour, government officials said Sunday.

yes a months worth of natural radioactivity . that is very very very very very very very low...very

better not touch that rock, it's radioactive

[ArtRosen]

yes a months worth of natural radioactivity . that is very very very very very very very low...very

Well, if it doesn't matter to them and it doesn't effect their health.. good for them. I'm glad. It's still a cause for concern that there is radiation leaking.

[gkrangers]

Fuel rods are fully exposed again per Kyodo.