Fukushima Japan earthquake - contamination & consequences outside Fukushima NPP

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121129/index.html The government is starting an investigation over the fact that more than half of the so-called earthquake-related deaths, which means people dying when health deteriorates during prolonged evacuation life, or 1100 deaths, are located in Fukushima prefecture. Conducting hearings of inhabitants and local governments, they will check if the evacuation and government help after the nuclear accident were appropriate. The results of the investigation are expected next autumn. A preparatory meeting was held at the Reconstruction agency on 29 November. Reconstruction minister Hirano says "Several kinds of inspections have been done, but we still lack a unified survey. Information such as who gave the evacuation order, in which situation, is still not clear. We want to record the fact relationships, and to learn lessons from those."

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121122/index.html The NRA's evacuation criteria study team composed of external experts started the main discussions on 22 November. On 22 November, they confirmed that they want to create Japan's own decision making standard regarding when to take iodine pills, based on the IAEA's standards as a reference, on the plant status, and on measured values. Fukushima Daiichi was victim of a manifold disaster including earthquake, tsunami, and measurements were not sufficient. One expert says "In addition to monitoring, it is suggested to make practical use of predictive systems".The study team will reach conclusions by the end of this year, so that local government bodies can prepare evacuation plans by the end of next March.

Is all this implying that there were previously no such guidelines and no such system in place? Isn't this the exact kind of thing that the IAEA is supposed to concern itself with?

 

[tsutsuji]

At some point, the US embassy in Japan issued an evacuation order/advice to leave the 50 miles (80 km) range around the plant. This included Fukushima City and Koriyama, the two largest cities in Fukushima Prefecture. This illustrates the fact that there is not a worldwide consensus on what people should do, upon which criteria, when this kind of event happens.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121130/1935_hp.html The ministry of Environment is starting a new website providing details on the decontamination progress status in each town or village. Where decontamination is performed under the direct responsibility of the national government, it is possible to find on maps the areas where decontamination has been started, and to access the radiation data before and after decontamination. Progress status of decontamination performed by local government bodies is also available.

http://josen.env.go.jp/ The new website.

http://josen.env.go.jp/area/details/pdf/naraha_h23_01.pdf For example, this is a report about the decontamination results around the town hall in Naraha town, with the radiation values before and after displayed on maps.

 

[zapperzero]

there is not a worldwide consensus on what people should do, upon which criteria, when this kind of event happens.

Certainly there isn't a consensus on what exactly to do in a particular scenario. I would have expected the IAEA to be much more serious about the existence and applicability of SAMGs, radioprotection and evacuation plans in general.

 

[nikkkom]

Still, a three year half life is only a tenth of the actual Cs 137 half life, so the recycling is only about 10%. Presumably the other 90% are swept away to the sea in the water flows.

Guys, please remember that Chernobyl exists. Use data from there.

IIRC in Chernobyl it was found that Cs is essentially trapped by forests, washout is slow.

The pine trees growing over trenches of buried Red Forest still experience growth deformities, not surprising considering that they have ~1 MBq/kg in their wood...

 

[zapperzero]

http://rpd.oxfordjournals.org/content/early/2012/12/02/rpd.ncs320.abstract
EARLY IN SITU MEASUREMENT OF RADIOACTIVE FALLOUT IN FUKUSHIMA CITY DUE TO FUKUSHIMA DAIICHI NUCLEAR ACCIDENT -

Masashi Takada and
Toshikazu Suzuki

Using a high-purity germanium detector, both indoor and outdoor radionuclides that had deposited 1.5 d after the radioactive fallout events in the city of Fukushima were experimentally measured. Eleven artificial (131I, 132I, 134Cs, 136Cs, 137Cs, 129Te, 129mTe, 131mTe, 132Te, 140La and 99mTc) and 5 natural radionuclides were identified. Total air kerma rates were mainly due to 132I, 134Cs and 136Cs from 4 to 6 µGy/h at a 7.5-cm height from the ground. Radioactive contamination on the ground was contributed by 132I and 132Te, from 330 to 420 Bq/cm2. In a worst-case scenario, the maximum skin dose rates were estimated to be from 520 to 670 µGy/h. Effective dose rates were evaluated to be 10 to 15 µSv/h and reached 17.9 µSv/h at 4 a.m. on 16 March. In the effective dose rates, 132I, 134Cs and 132Te were the main contributors. Our measurements are useful for estimating dose levels in the public in the city of Fukushima during the days after radioactive fallout contamination.

 

[zapperzero]

Apparently contractors hired for decon work in Fukushima prefecture are cutting (lots and lots of) corners, dumping radwaste into rivers and such.
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201301170063

 

[nikkkom]

Apparently contractors hired for decon work in Fukushima prefecture are cutting (lots and lots of) corners, dumping radwaste into rivers and such.
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201301170063

"The photos show a man repeatedly kicking fallen leaves into a river in Tamura, Fukushima Prefecture, on Dec. 14."

Tamura is 40 kilometers West from Fukushima and lies in the area with Cs-137 levels below <300kBq/m^2.

If I would live there, I would _much_ prefer Cs-137 impregnated leaves to be gone to Pacific Ocean and diluted to zero than lingering around in some shallow dumps for decades to come. (Shallow because it is financially impractically costly to dig deep ones for all woody material existing in 40+ km radius around Fukushima.)

I recognize that public supervision in the form of press coverage is necessary to keep contractors honest.

But it often goes to the the idiotic levels of mass hysteria due to appalling lack of basic education, and lack of WILL to learn some data before getting hysteric and demanding impossible - that everything needs to be cleaned up 100% while not shipping any contamination anywhere.

Material contaminated by Cs-137 can not be destroyed. Isotopes do not burn, you know. It can be either buried, or diluted. Burial is a good solution, and it should be used for highly contaminated material, but it can't be used for everything. There should be a level of contamination below which the material is allowed to be disposed of in a cheaper way - yes, including dumping it into Pacific.

 

[zapperzero]

There should be a level of contamination below which the material is allowed to be disposed of in a cheaper way - yes, including dumping it into Pacific.

As far as I know, dumping radwaste into oceans is a big no-no... Iirc the Russians had taken to putting waste in the North Sea? And there was a big stink about it? And then it was France? And again there was a big Stink?

 

[nikkkom]

As far as I know, dumping radwaste into oceans is a big no-no...

Uh oh. "Radwaste". You know, my poop is a "radwaste" too, it has 50 Bq/kg of K-40.

Where do you prefer Japanese to put 10 million tons of very slightly radioactive wood and leaves?

 

[Borek]

Several years ago Junior took a tourist trip to Chernobyl, and was told about results of different actions taken after the disaster.

Back in eighties during the cleaning up phase in some places they collected waste and covered it with the dirt/soil, and mounds are still radioactive. In other places it was not possible to collect the waste, so it was simply left and area was marked as no entry zone, and in the years that passed radioactive isotopes were flushed/diluted to the safe levels.

I am not trying to say dumping radwaste to oceans is a better solution, it is just that the final effect can be counterintuitive.

 

[nikkkom]

Back in eighties during the cleaning up phase in some places they collected waste and covered it with the dirt/soil, and mounds are still radioactive.

There are particular well-known mounds. He might have heard about *those*.

After the first few hectic weeks Soviets finally had time/resources to deal with Red Forest, which by that time was dead. (Immediately after the disaster Red Forest had ambient levels approaching 50 R/h).

They cut down the trees, dug deep trenches, and put the trees there, then piled soil over them. Unfortunately, they did not perform any water isolation. Eyewitnesses say even as they were filled, some trenches had water in them. And that wood has SERIOUSLY NASTY levels of contamination.

Currently, water slowly washes contamination out of these mounds.
Young pine trees reach with their roots to the buried wood and accumulate on the order of 1MBq/kg of Cs-137.

Here is the location of these mounds:

https://maps.google.com/?ie=UTF8&ll=51.382877,30.066211&spn=0.006401,0.017166&t=h&z=17&vpsrc=6

More photos of these mounds, and description, can be found here:

http://www.nuclearflower.com/zone/zone08.html

 

[zapperzero]

Uh oh. "Radwaste". You know, my poop is a "radwaste" too, it has 50 Bq/kg of K-40.

That's uncalled for and in any case it is irrelevant. Why bring it up?

Where do you prefer Japanese to put 10 million tons of very slightly radioactive wood and leaves?

Eh? I am sure there is no space in the comment box to describe all that should be done. I would certainly like the Japanese to follow the decon guidelines they have set for themselves, which they don't seem to be doing.

 

[nikkkom]

Eh? I am sure there is no space in the comment box to describe all that should be done. I would certainly like the Japanese to follow the decon guidelines they have set for themselves, which they don't seem to be doing.

Imagine a solid box of wood 1 by 1 kilometer in width and length, and 10 meters high.

Decontaminate that. Use of common sense is not allowed. Treat ALL OF IT as radwaste.

 

[zapperzero]

Imagine a solid box of wood 1 by 1 kilometer in width and length, and 10 meters high.

Decontaminate that. Use of common sense is not allowed. Treat ALL OF IT as radwaste.

What is your point, pray tell?

I shall try to interpret what you said as a question and answer it: Yes, there are big parts of Fukushima prefecture which should be off-limits to the public. Yes, this is because cleanup is too expensive. Yes, some of these areas should be fenced off to prevent excessive amounts of contaminated wildlife to exit, if possible.

Yes, every town and village which has been in the path of the plumes should be surveyed for hotspots. By hand. Inhabitants (especially members of civil response teams and emergency workers) should be taught how to do this themselves, provided with specialized support personnel, learning material, teaching material, counters and dosimeters. Public facilities should be set up for spot testing of food.

Yes, homes, roads and other public spaces such as parks(!) and schools(!) that have been contaminated should be decontaminated, even if this involves bulldozing them, loading them into dump trucks and dumping them in geofoil-lined trenches alongside the liquid radwaste tanks currently accumulating at the NPP.

Yes, the way radioactive substances move through the local environment should be studied, with a view to establishing where they are likely to re-concentrate after all this.

Repeat as needed, for about 250 years.

Sounds expensive? Well, the other sensible option is to just write it all off, like at Chernobyl.

 

[nikkkom]

What is your point, pray tell?

My point is that "contamination" is not a boolean variable.

My point is before screaming bloody murder about leaves being dumped into a river in a location 40 kilometers away from Fukushima 1, away from the plume ground track, I want to know how many Bq/kg of Cs-137 was in those leaves.

My point is that if we demand unreasonable results, we should not be surprised when things aren't done as we want.

NASA was pressed to launch Space Shuttle more often, to make its price-per-kg go down. Result? They were cutting corners and lost Challenger. Ten years later, when the shock wore off, it was repeated again: NASA was pressed to launch Space Shuttle more and often, to make its price-per-kg go down - it lost Columbia. (No, I am not just dreaming it up - I read both reports from cover to cover. Twice.)

What NASA _should have done_ is it had to admit that Space Shuttle CANT launch as often as they originally wanted, CANT be cost-efficient. It should have phased it out and replaced with a better system 20 years ago.

Yes, homes, roads and other public spaces such as parks(!) and schools(!) that have been contaminated should be decontaminated, even if this involves bulldozing them, loading them into dump trucks and dumping them in geofoil-lined trenches alongside the liquid radwaste tanks currently accumulating at the NPP.

Do you agree that it makes sense to sort the contaminated material by level of contamination and use less costly disposal methods for less contaminated material?

 

[zapperzero]

My point is that "contamination" is not a boolean variable.

My point is before screaming bloody murder about leaves being dumped into a river in a location 40 kilometers away from Fukushima 1, away from the plume ground track, I want to know how many Bq/kg of Cs-137 was in those leaves.

Enough that the decontamination procedure which had been decided upon was to collect them? But it was not followed, was it?

Do you agree that it makes sense to sort the contaminated material by level of contamination and use less costly disposal methods for less contaminated material?

Yes. But, this is not what happened here. The less costly disposal method was not used, instead, a no-cost dispersal method was used, against specific instructions, which has unpredictable consequences.

EDIT: By dumping randomly into rivers, you might indeed flush the stuff right out into the ocean, immediately. But rivers don't really work like that... you might be adding to problems such as these, instead:
http://www.youtube.com/watch?v=lk6YSOK3Uz8&feature=g-u-u
http://www.youtube.com/watch?feature=player_embedded&v=hHqGmZLtmVw

 

[zapperzero]

Report on a probe into reactor 1 torus room.
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130220_02-e.pdf

 

[zapperzero]

It appears that the monitoring posts in Fukushima prefecture (you know, the ones that were not posting measurements online in the days after the accident?) were actually active.

http://mainichi.jp/english/english/newsselect/news/20130222p2a00m0na009000c.html

However, data at four monitoring posts in the Koriyama, Yamada, Kamihatori and Shinzan districts in the Fukushima Prefecture town of Futaba indicated that radiation levels had risen hours before TEPCO starting opening the vents.

Radiation dosages in the four areas before the disaster ranged between 0.04 and 0.05 microsieverts per hour, but as of 5 a.m. the level in the Koriyama district, located about 2.5 kilometers north of the plant, had swelled to 0.48 microsieverts per hour and at 6 a.m. it stood at 2.94 microsieverts per hour. By 9 a.m., roughly one hour before officials started opening the vent, the hourly radiation level had surged to 7.8 microsieverts. In the Yamada district 5.5 kilometers west of the power plant, the radiation level at 10 a.m. had increased to 32.47 microsieverts per hour -- roughly 720 times the normal figure.

 

[nikkkom]

Report on a probe into reactor 1 torus room.
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130220_02-e.pdf

Maximum is 100 R/h :(

This room will give tens of rems per hour for any visitor for the next 50 years.

That's why I feel trying to fully clean such things up is a waste of money. Pump it out, waterproof, and fill with concrete. 300 years from now when Cs and Sr will be gone, our grand-grandchildren can deal with it.

 

[zapperzero]

Maximum is 100 R/h :(

This room will give tens of rems per hour for any visitor for the next 50 years.

That's why I feel trying to fully clean up such things up is a waste of money. Pump it out, waterproof, and fill with concrete. 300 years from now when Cs and Sr will be gone, our grand-grandchildren can deal with it.

Yes, Nikkom, let's keep kicking that can down the road, why don't we?
Oh, wait.

 

[nikkkom]

Yes, Nikkom, let's keep kicking that can down the road, why don't we?

It will cost upwards of $50B to completely dismantle F1 units and ship all contaminated materials off-site, and it will take at least many tens of years anyway. TMI is still not dismantled, and that site is child's play compared to this mess.

Do you realize what "ship contaminated materials off-site" means?

It means this radioactive stuff will STILL EXIST, just moved somewhere else at humongous expense. Why can't it be stored where it is now?

 

[zapperzero]

It will cost upwards of $50B to completely dismantle F1 units and ship all contaminated materials off-site, and it will take at least many tens of years anyway. TMI is still not dismantled, and that site is child's play compared to this mess.

Do you realize what "ship contaminated materials off-site" means?

It means this radioactive stuff will STILL EXIST, just moved somewhere else at humongous expense. Why can't it be stored where it is now?

Do you realize that I have exactly zero pity for poor TEPCO? Do you realize that I do not care if the company is bankrupted and has to sell all its assets to pay for this, and for off-site decon? It's their plant, it blew on their watch. The site needs to be returned to greenfield. Eventually.

Or would you rather that all NPPs be left to rot at the end of their useful lives? Shall we dot the Earth with radioactive sarcophagi? Waste volume reduction is not just someone's lark, you know? It serves a real purpose.

 

[nikkkom]

Do you realize that I have exactly zero pity for poor TEPCO?

TEPCO won't pay for it in either case. Japanese taxpayers will.

 

[zapperzero]

TEPCO won't pay for it in either case. Japanese taxpayers will.

Well then they're stupid, I am sorry to say. The accident was not their fault, mostly.

 

[nikkkom]

On this page:

http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=NP-6931

it is possible to download NP-6931.pdf -

"The Cleanup of TMI-2
A Technical History: 1979 to 1990"

I just now finished reading it from cover to cover.

zapperzero, mind taking a look?

Page 7-13 describes joys of decontaminating of some concrete
impregnated with fission products with dose rates
up to 1000 rem/hour.

Fukushima is expected to be worse than that.

 

[zapperzero]

zapperzero, mind taking a look?

Page 7-13 describes joys of decontaminating of some concrete
impregnated with fission products with dose rates
up to 1000 rem/hour.

Fukushima is expected to be worse than that.

No, I don't mind, but what is the relevance to our discussion? Of course it is hard and expensive and dangerous. Of that there is no doubt.

 

[zapperzero]

Confirmation that the "dumping radwaste into the river" incident was not isolated:
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201303010084

 

[nikkkom]

No, I don't mind, but what is the relevance to our discussion? Of course it is hard and expensive and dangerous.

There are different degrees of "hard". The report will give you a good idea how hard it was at TMI-2.

 

[zapperzero]

There are different degrees of "hard". The report will give you a good idea how hard it was at TMI-2.

Well, it has. Now what?

 

[nikkkom]

Well, it has. Now what?

Now you have more information to base your opinions on.

You, for example, now know that in a relatively benign accident at TMI-2, containment basement was flooded "merely" by reactor coolant, and it proved to be impossible to clean that basement up. Its concrete was flushed, it was scrubbed, its outer surface was scarified away by robots. Nothing of the above made the basement clean enough to allow human entry. Thirty-three years after that accident, it is still not fully cleaned up.

Fukushima basements will be *much* worse than that.

 

[zapperzero]

Fukushima basements will be *much* worse than that.

Yes. And?

 

[nikkkom]

Yes. And?

Okay. You are in charge of the cleanup. What is your plan? How do you propose to clean up containment and torus?

 

[zapperzero]

Okay. You are in charge of the cleanup. What is your plan? How do you propose to clean up containment and torus?

Nonono. It doesn't go like this. Show your hand. You have been insinuating and implying and suggesting for far too long and I have no more patience. What do YOU propose?

 

[nikkkom]

Nonono. It doesn't go like this. Show your hand. You have been insinuating and implying and suggesting for far too long and I have no more patience. What do YOU propose?

Wait until decay heat is low enough for corium to not overheat when isolated (it may already be low enough). While waiting, install air filtration, water filtration system and evaporator. Prepare storage for spent filtration vessels (likely to be high-activity).
Prepare dry waste storage for evaporator scale (low-activity waste).

Pump out torus room and drywell and vacuum dry both. Completely fill torus room with concrete. (None of these operations require personnel ingress. In particular, no sediment or corium removal from torus room is done.) If simulations deem it necessary for heat removal, embed heat pipes into this concrete and route them into rooms above torus.

This leaves reactor buildings' basements sealed and their radioactivity immobilized under several meters of concrete, all below ground level, protected against weathering and with no active measures necessary.

Your plan is ... ?

 

[zapperzero]

Wait until decay heat is low enough for corium to not overheat when isolated (it may already be low enough).

It will continue decaying and thus making heat for a very very long time. We don't even know how dense it is.

While waiting, install air filtration, water filtration system and evaporator. Prepare storage for spent filtration vessels (likely to be high-activity).
Prepare dry waste storage for evaporator scale (low-activity waste).

This is already MORE than has been done at Fukushima so far.

Pump out torus room and drywell and vacuum dry both.

I am now left dealing with several hundred tons of slurry which the pumps can't get at, comprised variously of bits of equipment, fuel debris and water. Better pray for no fission excursions!

Completely fill torus room with concrete. (None of these operations require personnel ingress. In particular, no sediment or corium removal from torus room is done.) If simulations deem it necessary for heat removal, embed heat pipes into this concrete and route them into rooms above torus.

How long do these pipes need to last? And again, what about reactivity control?

This leaves reactor buildings' basements sealed and their radioactivity immobilized under several meters of concrete, all below ground level, protected against weathering and with no active measures necessary.

This leaves the fuel in an unknown state, with no means to check on it and no means to get it out easily, or indeed at all. There is still underground water flowing around (and probably in) the basements. How long until water, earthquakes and the action of the fuel itself (heating, alphas, fast betas and neutrons) cracks the new concrete and starts leaching stuff away to who knows where, dispersing and re-accumulating at random?

Your plan is ... ?

I don't have a plan. I look at TEPCO's plan and I think it's decent in its intent, if overly optimistic and too reliant on the TMI experience. Generally speaking, the entire thing (reactor buildings and their environs) needs to be crunched into small bits, the low- and medium- level waste can be stored on site containerized, in bunkers, while the highly radioactive material needs to be concentrated as much as safely possible and dumped into long-term storage.

Fuel in the pools should go to reprocessing. Fuel in the reactors should probably be just stored.

Only, I have no answers for secure long-term storage of nuclear waste, but that doesn't make me an idiot because no-one else has either.

 

[nikkkom]

I don't have a plan.

My point.

Generally speaking, the entire thing (reactor buildings and their environs) needs to be crunched into small bits,

Could not be done even on TMI-2.

 

[nikkkom]

I am now left dealing with several hundred tons of slurry which the pumps can't get at, comprised variously of bits of equipment, fuel debris and water. Better pray for no fission excursions!

You missed "vacuum dry it" part. There wouldn't be much water.

As to reactivity excursions, the fuel in torus and torus room (if any) is lying on the floor. It can't magically roll up into a ball. Not to mention that more detailed plans, naturally, would include neutron poison materials in the concrete.

How long do these pipes need to last?

About 10 years, until decay heat falls to really low levels.

This leaves the fuel in an unknown state,

Look like well-known state to me: "encased in concrete". Most spent fuel on this planet so far is in LESS secure state than this one.

with no means to check on it and no means to get it out easily, or indeed at all. There is still underground water flowing around (and probably in) the basements.

Not more than there is water flowing inside Hoover dam. Stands for 80 years already.

How long until water, earthquakes and the action of the fuel itself (heating, alphas, fast betas and neutrons) cracks the new concrete and starts leaching stuff away to who knows where, dispersing and re-accumulating at random?

With proper design, after thousands of years. More likely outcome is that it will be dismantled before then.

 

[zapperzero]

The news site that will not be named posted a link to an article regarding contamination on the grounds of the Canadian embassy in Tokyo.
http://link.springer.com/article/10.1007/s10967-012-2040-3

In this study, soil samples were collected at Canadian embassy in Tokyo (about 300 km from Fukushima) on 23 March and 23 May of 2011 for purposes of estimating concentrations of radionuclides in fallout, the total fallout inventory, the depth distribution of radionuclide of interest and the elevated ambient gamma dose-rate at this limited location [...] The total fallout inventory was thus calculated as 225 kBq/m2 on March sampling date and 25 kBq/m2 on May sampling date.

For reference, the zone of permanent control around Chernobyl was defined as > 555 kBq/m^2 while the zone of periodical control starts at 185 kBq/m^2.
http://fukuleaks.files.wordpress.com/2011/10/591px-tchernobyl_radiation_1996-de-svg.png

 

[zapperzero]

You missed "vacuum dry it" part. There wouldn't be much water.

How much is too much? How much is just enough for moderation purposes in a bed of fuel particles? What little I've read suggests 50%

As to reactivity excursions, the fuel in torus and torus room (if any) is lying on the floor.

You don't know that.

Look like well-known state to me: "encased in concrete". Most spent fuel on this planet so far is in LESS secure state than this one.

Obviously this is not the case...

Not more than there is water flowing inside Hoover dam. Stands for 80 years already.

Hoover Dam is filled with natural rock. It is not a concrete dam. And no, if water was flowing through cracks in it, it would not have resisted for 80 years.

With proper design, after thousands of years. More likely outcome is that it will be dismantled before then.

Proper design of what? Dismantled how? You are just advocating that TEPCO should dump concrete in the reactors. Do you think that maybe someone can go in first and waterproof everything?

Your sole preoccupation seems to be with the costs incurred by TEPCO. I wonder why? Perhaps you are a shareholder? Because a responsible citizen of Earth you are certainly not.

 

[LabratSR]

Saw this today. Not sure where to put it.

http://www.newscientist.com/article/dn23307-us-soldiers-sue-over-fukushima-radiation-exposure.html

 

[nikkkom]

You are just advocating that TEPCO should dump concrete in the reactors.

No, I propose that rooms *around and under* drywell and reactor should be filled with concrete without attempting to competely clean them up.

Then drywell can be reflooded, reactor cap can be opened. Most likely, the vast majority of the corium will be in this volume, not elsewhere.

 

[zapperzero]

No, I propose that rooms *around and under* drywell and reactor should be filled with concrete without attempting to competely clean them up.

Then drywell can be reflooded, reactor cap can be opened. Most likely, the vast majority of the corium will be in this volume, not elsewhere.

What you are proposing is, among other things, illegal. There are laws in Japan (mandated at least to some extent by international treaties) about nuclear fuel accountability.

You can't just say "oh, it's in there somewhere".

 

[nikkkom]

Hoover Dam is filled with natural rock. It is not a concrete dam. And no, if water was flowing through cracks in it, it would not have resisted for 80 years.

Exactly my point. Water isn't flowing through Hoover Dam, despite being under pressure of more than 20 atm at the bottom. We know how to make concrete which is impermeable for water. We know it for at least 100 years already.

 

[nikkkom]

What you are proposing is, among other things, illegal. There are laws in Japan (mandated at least to some extent by international treaties) about nuclear fuel accountability.

You can't just say "oh, it's in there somewhere".

Why it can't be said? It *is* the truth - the corium is there. Would anyone honestly suspect that "evil TEPCO" clandestinely removed some corium from the torus room before pouring concrete? That would be just idiotic and pointless thing to do, not to mention technically hard.

What nuclear fuel accountability rules say about accounting for a few hundreds of kilograms of Caesium from spent fuel which is already dispersed far and wide by now? About a few kilograms of tritium lost? About Kr-85? Looks like TEPCO is in breach already :/

 

[cockpitvisit]

a few hundreds of kilograms of Caesium from spent fuel

I think it is just 4 kg of Caesium. The total Cs-137 release was estimated at 13,600 TBq, and one kg of Cs-137 has 3,215 TBq.

And I thought Kr-85 and tritium are always being released into the atmosphere by reprocessing plants, or am I wrong here?

 

[clancy688]

I think it is just 4 kg of Caesium. The total Cs-137 release was estimated at 13,600 TBq, and one kg of Cs-137 has 3,215 TBq.

That's only what went into the atmosphere. According to IRSN, at least double that number again went into the ocean.

 

[zapperzero]

I wonder if someone here could confirm or infirm this? http://ex-skf.blogspot.ro/2013/03/radioactive-japan-50-millisieverts.html
There's crazy talk in there about commuting to work being allowed in 50 mSv/y areas.

 

[Sorai]

I wonder if someone here could confirm or infirm this? http://ex-skf.blogspot.ro/2013/03/radioactive-japan-50-millisieverts.html
There's crazy talk in there about commuting to work being allowed in 50 mSv/y areas.

I don't think residents are supposed to commute and work regularly in those areas, at least on paper. You can read a definition of the three zones in this document from December 2011: http://www.meti.go.jp/english/earthquake/nuclear/roadmap/pdf/20111226_01.pdf

In relation to areas between 20 and 50 mSv/year ("Areas in which the residents are not permitted to live"):

"In this case, residents are ordered to remain evacuated in the areas, but people concerned can temporarily return home in the areas (but staying overnight is prohibited), pass through the areas along main roads, and enter the areas for purposes beneficial to the public interest, such as repairing the infrastructure and conducting disaster prevention-related work." [p. 10]​

Based on more recent Japanese documents, it does not seem like the definition has changed, though I guess residents would be able to commute daily as long as they can justify that their work is related to repairing basic infrastructure. Even in that case, they would only be exposed to part of the annual dose, since they are not allowed to stay overnight.

However, I've read of at least one farmer, Naoko Matsumura, who went back to the exclusion zone very early on after the accident and lives there taking care of his animals, so it seems the police is not forcing people to evacuate if they decide to stay: http://www.dailymail.co.uk/news/art...led-Fukushima-nuclear-plant-care-animals.html