Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[tsutsuji]

and the energy of the ignition source

I think that what Miyake (not Mitake) is saying, although it is not very clear, is that you must calculate the energy added by the burning of materials other than hydrogen that are present in the building.

On June 4th, NISA approved to store more contaminated water from unit 2 into the process main building of the waste treatment facility. Contaminated water will be added until the OP+4200 mm level (below the "run through" part in the 1st basement ; this is still lower than the ground water level), is reached (instead of the previous OP+3700 mm : filling of the 2nd basement only), and the storing capacity will reach 11,500 m^3 (instead of 10,000 m^3) : http://www.meti.go.jp/press/2011/06/20110604003/20110604003.html (includes request letter from Tepco and reply letter from NISA)

The process main building had been filled up to OP+4138 as of June 6th 7:00 JST : http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110606_01-j.pdf

 

[joewein]

It was reported that there were 32 MOX fuel assemblies in Unit 3, or about 6% of the core of 548 assemblies. They were operating in their first cycle, so they didn't have much operation/exposure. Ostensibly, the MOX fuel was derived from spent fuel from the Fukushima reactors, thus it was reactor grade, and the Pu isotopics would have reflected that legacy. The MOX fuel would be designed to match the enrichment of the U-235 assemblies, which is about 4% U-235. So likely the MOX would be about 6% Pu, with a mix of Pu239, 240, 241 and 242.

Spent fuel contains Pu isotopes. The use of MOX is rather insubstantial to the event and the current state of Unit 3.

I agree, this problem is largely overestimated. Most non-technical observers are unaware of the plutonium levels in burnt up fuel rods. I recall from literature about reprocessing plants that about 1% Pu (produced through neutron capture from U238) remains in waste from LWR fuel initially enriched to 5% U235.

Unit 1 and unit 6 used fuel enriched to 3.4% U235, unit 2-5 to 3.6% U235. If in fully burnt up fuel the equivalent of 1/5 of the U235 fuel stays behind as unfissioned Pu, that would be about 0.7% by weight in those BWRs. Assuming the fuel was on average half burnt up at the time of the accident, as it is replaced in portions (1/3 at a time?), let's make that 0.35% of the total.

In the MOX reactor, in 6% of fuel rods 6% by weight would be plutonium when starting it up again. That's about 0.36%, on top of the Pu in spent uranium rods (94% of the rods).

While the MOX scenario means an increase of plutonium in the core compared to enriched uranium fuel (maybe a doubling at the worst case), some media reports make it sound like Pu was a new worry created through the use of MOX fuel, which it definitely is not. Units 1 and 2 collectively may well contain more plutonium that does unit 3.

 

[jlduh]

I appreciate the mistrust/distrust of the nuclear industry. The event at Fukushima has betrayed whatever trust had been established.

I appreciate that you honestly recognize this. And to continue on this subject (but moving on the more political thread), I think one of the root causes of this distrust situation is maybe summarized in this message i just posted, based on a declaration of the chairperson of Japan's Nuclear Safety Commission, Haruki Madarame:

https://www.physicsforums.com/showpost.php?p=3341445&postcount=284

 

[zapperzero]

http://mdn.mainichi.jp/mdnnews/news/20110606p2a00m0na009000c.html

Airborne contamination estimates revised upwards by NISA "from 370,000 terabecquerels to 850,000 terabecquerels", counting from the start of the accidents to April 5.

 

[clancy688]

http://mdn.mainichi.jp/mdnnews/news/20110606p2a00m0na009000c.html

Airborne contamination estimates revised upwards by NISA "from 370,000 terabecquerels to 850,000 terabecquerels", counting from the start of the accidents to April 5 (yesterday).

Now it's 20% Chernobyl...

 

[tsutsuji]

http://mdn.mainichi.jp/mdnnews/news/20110606p2a00m0na009000c.html

Airborne contamination estimates revised upwards by NISA "from 370,000 terabecquerels to 850,000 terabecquerels", counting from the start of the accidents to April 5 (yesterday).

April 5 is two months ago. (Yesterday is June 5)

 

[jlduh]

Yeah, there are not too many places that make MOX fuel. This article is about a year old and says:
Taken from http://www.world-nuclear-news.org/WR_Japanese_firms_stick_with_Sellafield_MOX_Plant_1305101.html

Also we can see how the MOX stuff has been a very slow process with many delays along the way, with this article which seems to be over a decade old:

http://www.atimes.com/japan-econ/AI18Dh01.html

You have a quite detailed summary of some Japanese reactors MOX conversion here, with dates (many delays...):

http://cnic.jp/english/topics/cycle/MOX/pluthermplans.html

Somebody (maybe Jim? I don't remember exactly sorry!) wrote that Belgonucleaire was making MOX for Areva.

This was true (Belgo made rods and Areva assembled them and sold them) until Areva started their big MOX production plant in Marcoule (France). Areva has been a customer for Belgo for years but obviously then shifted to use their own fuel/rods. Belgo quality standards for MOX have suffered criticism in the past.

Belgo has stopped producing MOX in 2006. This is stated on their site: http://www.belgonucleaire.be/uk/default.htm

WELCOME TO THE BELGONUCLEAIRE WEBSITE

During more than 20 years, BELGONUCLEAIRE has produced
MOX (Mixed OXides) fuel for nuclear power plants.
The last fabrication campaign has been completed on 15 August 2006.

Their Dessel plant is now to be decommissionned. So It's pretty clear that they didn't make the MOX delivered in 2010 for Fukushima N°3. Areva did it.

Interestingly, the Areva site doesn't list Tepco being one of their suppliers:

http://www.areva.com/EN/operations-1095/melox-operations-production-of-mox-fuel-assemblies.html

But... is it surprising really? Or is it just communication strategy
On the other hand, they already made MOX with plutonium grade:

In 2003, the AREVA group was chosen by the United States to produce 4 MOX fuel assemblies from American plutonium of military origin.

The production of these assemblies was carried out on 2 sites.

Fabrication of pellets and rods took place at the AREVA NC Cadarache facility in the fall of 2004.
Fuel assembly operations took place at the MELOX plant in early 2005.
The 4 assemblies produced were loaded in June 2005 into the Catawba nuclear power plant, owned by the American electrical utility company Duke Power. They have enabled the production of power sufficient to meet the electricity demands equivalent to those of a city of nearly 10,000 inhabitants a year. The American program demonstrates that civil nuclear applications, and the use of MOX in particular, can contribute to the non-proliferation of nuclear weapons.

 

[tsutsuji]

Following the (still untranslated ?) May 24th Tepco report explained on http://www.tepco.co.jp/en/press/corp-com/release/11052412-e.html , the NISA asked JNES to cross-check the Tepco study about the state of the cores of units 1,2,3. While Tepco used a software called MAAP, JNES used another software called MELCOR. The conclusions have been published by NISA on a document dated June 6th : http://www.meti.go.jp/earthquake/nuclear/pdf/20110606-1nisa.pdf (in Japanese). Page 26/59 is a series of diagrams showing the state of the core of unit 1 after 6, 12 and 18 hours.

Concerning Tepco's response to the ever-growing amounts of contaminated water, NISA published the following documents :

On June 2nd an 18 page document : http://www.meti.go.jp/press/2011/06/20110602002/20110602002.pdf including, page 9, a map with the various trenches, electric cables, sea water pipes, etc... with their elevations, between the turbine buildings and the water intake canal. The dot lines show the various leaking paths that must be closed. Page 16 is a schedule for the works undergoing in May and June.

On June 3rd, a 17 page document : http://www.meti.go.jp/press/2011/06/20110603002/20110603002.pdf including simulation plots showing the contaminated water levels in the turbine buildings until September.

 

[zapperzero]

April 5 is two months ago. (Yesterday is June 5)

yes, of course. edited

 

[swl]

Now it's 20% Chernobyl...

Another year of contaminated steam, then add in the water leaks, and we should be well on our way to that elusive #1 spot (of all time accidents).

Rainy season is upon us. Anyone taking bets?

 

[Rive]

Rainy season is upon us. Anyone taking bets?

http://www3.nhk.or.jp/daily/english/06_15.html
So, actual amount is ~105000m³, pacing with 500m³/day, overflow expected on 06.20.
Water decontamination facility may be online on 06.15. They are installing new storage capacity of 30000m³.

It'll be a close run... But they have some chance. If nothing unexpected happens.

Ps.: the facility will be online at 06.15... Edited.

 

[WhoWee]

If nothing unexpected happens.

That is one big "IF" - isn't it?

 

[joewein]

Another year of contaminated steam, then add in the water leaks, and we should be well on our way to that elusive #1 spot (of all time accidents).

Rainy season is upon us. Anyone taking bets?

At 500 t a day injected for cooling, I suppose in the worst case TEPCO (or JP tax payers) will have to purchase steel tanks equivalent to about 200,000 t over the next 12 months, if the AREVA plant that is supposed to reprocess 200,000 t by the end of the year turns out to not work as advertised. We know 40,000 t are on order already.

Does anyone know at what stage the desalination takes place in the AREVA plant? I am curious how they'll separate the cesium from the sodium/potassium.

I guess one possibility would be not to bother and keep all alkali ions together, putting the sodium/potassium in long term storage too for now. At 0.5x-0.8x salinity compared to sea water there should be 170-180t of salt in 100,000 t of brackish water from the reactors, turbine basements and various tanks.

 

[rowmag]

At 500 t a day injected for cooling, I suppose in the worst case TEPCO (or JP tax payers) will have to purchase steel tanks equivalent to about 200,000 t over the next 12 months, if the AREVA plant that is supposed to reprocess 200,000 t by the end of the year turns out to not work as advertised. We know 40,000 t are on order already.

I still wonder at what point it makes sense to seal up the harbor entrance and declare it a giant storage/evaporation pond.

 

[jlduh]

Concerning the 950 mSv/h debris:
http://www3.nhk.or.jp/daily/english/06_28.html

On Monday, a piece of debris about 5 centimeters in diameter with radiation levels of 950 millisieverts per hour was removed from the west side of the Number 3 reactor building. It had been found on Saturday.In May, debris with a radiation dose of 1,000 millisieverts per hour was discovered in the area, while rubble contaminated with 900 millisieverts per hour was found in April.

Tokyo Electric Power Company has so far removed about 280 containers of radioactive debris, but radiation levels still remain high near the reactor building that was badly damaged by a hydrogen explosion.

 

[elektrownik]

http://www3.nhk.or.jp/daily/english/06_33.html"

 

[jlduh]

http://www3.nhk.or.jp/daily/english/06_33.html

No.1 reactor vessel damaged 5 hours after quake

Japan's nuclear regulator says the meltdown at one of the Fukushima reactors came about 5 hours after the March 11th earthquake, 10 hours earlier than initially estimated by the plant's operator.

[...]

The report says the fuel rods in the Number 1 reactor began to be exposed 2 hours after the earthquake due to the loss of the reactor's cooling system in the tsunami. Its fuel rods may have melted down 3 hours later, causing the damage to the reactor. This means the meltdown occurred about 10 hours earlier than TEPCO estimated last month.

The nuclear agency also says a meltdown damaged the Number 2 reactor about 80 hours after the quake, and the Number 3 reactor 79 hours after the quake.

The agency's analysis shows that the Number 2 reactor damage came 29 hours earlier than the TEPCO estimate, and the Number 3 reactor damage came 13 hours later than in the utility's assessment.

The agency says the total amount of radioactive iodine 131 and cesium 137 released from the Numbers 1, 2 and 3 reactors for the 6 days from March 11th is estimated at 770,000 terabecquerels. That is about twice the figure mentioned in April when the agency upgraded the severity of the accident to the highest level of 7 on an international scale.

 

[etudiant]

At 500 t a day injected for cooling, I suppose in the worst case TEPCO (or JP tax payers) will have to purchase steel tanks equivalent to about 200,000 t over the next 12 months, if the AREVA plant that is supposed to reprocess 200,000 t by the end of the year turns out to not work as advertised. We know 40,000 t are on order already.

Does anyone know at what stage the desalination takes place in the AREVA plant? I am curious how they'll separate the cesium from the sodium/potassium.

I guess one possibility would be not to bother and keep all alkali ions together, putting the sodium/potassium in long term storage too for now. At 0.5x-0.8x salinity compared to sea water there should be 170-180t of salt in 100,000 t of brackish water from the reactors, turbine basements and various tanks.

There is a more detailed schematic of the process given on EX-SKF here:
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-water.html
The key element appears to be the selective cesium removal, before precipitating out the other radio nucleotides. Desalination is only done after that.
The cesium removal material is supplied by Kurion, ( http://www.kurion.com ) a private company in Irvine, CA. Their website gives links to papers suggesting their inorganic adsorption material is extraordinarily selective for cesium, at a 100,000 to 1 ratio. They also claim to have supplied some earlier material for the TMI cleanup.
As has been noted earlier, we will soon find out how well this works for Fukushima. We can only hope for a complete success.

 

[tsutsuji]

Concerning the 950 mSv/h debris:
http://www3.nhk.or.jp/daily/english/06_28.html

The 00:12 time-frame of the video is circling with a yellow circle the red-coloured debris at the bottom of the cone.

Here are the links for the Tepco picture: http://www.tepco.co.jp/en/news/110311/images/110605_02.jpg and map: http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1-sv-20110605-e.pdf again.

An employee interviewed by http://mainichi.jp/select/weathernews/news/20110531ddm041040136000c.html says he is afraid to work without a radiation control technician coming along, while he suspects that debris are "falling" (from walls or ceilings ? or from rubble stacks ?). Their own radiation monitor is inside their clothes so they can't see it, and they can't hear the alarm if it rings because they are wearing a mask.

 

[robinson]

http://www.tepco.co.jp/en/news/110311/images/110605_02.jpg

Am I the only one who is thinking, "Why not use a long pole and pick that up and remove it to the storage area for radioactive crap?".

Why leave it there? Or did they already do that you think?

 

[Bioengineer01]

AREVA does not fabricate MOX fuel in the US.

Please post the export permits that one 'saw'.

TEPCO has reprocessing contracts with AREVA. There is strict control of spent fuel and MOX fuel. TEPCO indicates that MOX is derived from spent fuel.
http://www.tepco.co.jp/en/challenge/csr/nuclear/cycle-e.html

The status of MOX fuel is posted earlier in this thread.

I found the place where I saw it, it was a permit for 35 Tons of Uranium Oxide UOX for Fukushima Daiichi. Not MOX, the guy called it MOX, and my brain didn't remember right.
http://lunaticoutpost.com/Topic-Nuclear-Power-plant-Onagawa-on-fire-Fukushima-malfunctions?pid=916175#pid916175
The link to the permit was at http://www.box.net/shared/g6sm3p376b , I did see it myself along many others in the thread I reference above, you can check it yourself, there is discussion about it for several pages. But It is gone now.

 

[tsutsuji]

http://www.tepco.co.jp/en/news/110311/images/110605_02.jpg

Am I the only one who is thinking, "Why not use a long pole and pick that up and remove it to the storage area for radioactive crap?".

Why leave it there? Or did they already do that you think?

Jlduh's quote at https://www.physicsforums.com/showthread.php?p=3341761#post3341761 says it has been removed.

 

[Bioengineer01]

Really good observation.
You remind me what happened in russia then...
Mr. Dyatlov, manager of the blown-up block in Chernobyl insisted that the reactor was still there, intact, being cooled.
He was unable to be convinced that the reactor was damaged until helicopters filmed the situation from above next noon.
This delayed many emergency measures.


In Russia military quickly took over to remedy the situation.
In Fukushima also constantly new procedures are being developed.

First step should always be a thorough assessment of the situation.
Then the necessary measures must be developed or improvised.
Layman input at least is not restricted by procedure thinking obsoleted by new situations.

So to get back to the reactor problem:
There are questions not asked before even in this thread.

What fraction of the short-lived fission products can be expected to already have left the reactors and taken away by the cooling water?

If, for example, as some sources say, almost all iodide and cesium has been dissolved into the tens of thousands cubic meters of water, then a big part of the residual heat could now have left the reactor remains.

So my second and third question:
Does this bleed-out of FPs reduce residual heat substantially?
If so, what magnitude could be the probable reduction of core remains' residual heat?

Why I ask this:
There will eventually be a point of equilibrium when the heat can sufficiently passively dissipate through floors, walls etc slowly without melting anything more.
From this point on, the way most economical solution would be entombing.


I'd be happy if some nuclear professional could comment on how much of the FP inventory is still in the reactors.
Thank you!

Two points: The pilots of the helicopter paid Mr. Dyatlov's mistake with their lives soon thereafter the fly by...

The answer to the second question depends on the geommetry of the situtation, if the Corium is in the form of a blow with the external layer solidified by the contact with water vapor and the inside of the mass is liquid, very little of what goes on inside will be extracted by the water. If on the contrary it is distributed in a granular way all over the place presenting multiple surfaces of contact to the water vapor, the a lot would be washed by the water.

 

[Bioengineer01]

I think TEPCO has plans to formulate their own MOX fuel in the future, but I was also under the impression that the MOX fuel in use there currently came from AREVA and shipped from France.

http://www.world-nuclear-news.org/ENF-Japan_starts_using_MOX_fuel-0511094.html

So up until now, it was devrived from Japanese spent fuel and it did come from France. Both statements are true.

Funny then that the spent fuel is Japanese, the UOX is from the USA and the MOX from France :)

 

[robinson]

Jlduh's quote at https://www.physicsforums.com/showthread.php?p=3341761#post3341761 says it has been removed.

Thanks. I somehow missed that.

 

[tsutsuji]

http://www3.nhk.or.jp/daily/english/06_33.html
No.1 reactor vessel damaged 5 hours after quake

This is probably what is meant on the diagram page 17 of the report I mentioned :

the NISA asked JNES to cross-check the Tepco study about the state of the cores of units 1,2,3. While Tepco used a software called MAAP, JNES used another software called MELCOR. The conclusions have been published by NISA on a document dated June 6th : http://www.meti.go.jp/earthquake/nuclear/pdf/20110606-1nisa.pdf (in Japanese).

 

[Bioengineer01]

There has been considerable math and forumlas developed, but there are still a lot of unknowns. Kids not even born yet will be writing their PhD theses about Fukushima a few decades from now.

Anyone interested in the corium aspects of this situation should have a look at the following pdf reports:

http://www.tec-sim.de/images/stories/lecturenotes-late-in-vessel-phenomena.pdf
http://www.tec-sim.de/images/stories/severe-accident-phenomenology.pdf

They are fairly recent and summarize the current state of knowledge regarding "corium". The most interesting thing I found out, is that 25 years after TMI2 there is still no explanation for why the molten corium did not melt through the reactor vessel. All simulations indicate that it should have happened, but it didn't. To this day nobody can explain it. There is a lot we don't know.

Interesting bullet point on re-criticality on second link:
"Recriticality
If there water in the lower head, recriticality due to U235 cannot be
excluded.
Rule-of-thumb: If there is no water, recriticality can be excluded if
Uranium enrichment is below 5%
The amount of Pu239 is more than enough for recriticality but this would
require local Pu accumulation, which has not yet been investigated."

 

[dh87]

http://mdn.mainichi.jp/mdnnews/news/20110606p2a00m0na009000c.html

Airborne contamination estimates revised upwards by NISA "from 370,000 terabecquerels to 850,000 terabecquerels", counting from the start of the accidents to April 5.

The previously reported 370,000 TBq release is from p. 20 of this document (dated 4/25): http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e.pdf

The document says 130,000 TBq of I-131 and 6,000 TBq of Cs-137. Then, there's a mysterious "Iodine value conversion" before apparently adding the numbers to get 370,000 TBq.

I could not find a breakdown of the new numbers to determine what they think is different. The Mainichi article linked earlier says "The Cabinet Office's Nuclear Safety Commission of Japan (NSC) had estimated that the total level of radioactivity stood at around 630,000 terabecquerels, but this figure was criticized as an underestimation." If enough people criticize the new estimate, maybe it will be revised too.

 

[radio_guy]

All this talk of AREVA and their treatment plant..

whatever happened to this guy?
http://blogs.wsj.com/japanrealtime/2011/04/21/chemist-i-can-clean-fukushima-water-faster/

They are working a close (5 day) deadline to overflowing... maybe they should give it a shot? I'm sure areva won't lend their new on site plant for testing, but they really don't have a lot to lose if it doesn't work as planned...

this is one of those situations where they should give this guy and the company what they want and use the solution, no politics, less industry nepotism, pick THE best solution and run with it.

 

[thehammer2]

All this talk of AREVA and their treatment plant..

whatever happened to this guy?
http://blogs.wsj.com/japanrealtime/2011/04/21/chemist-i-can-clean-fukushima-water-faster/

They are working a close (5 day) deadline to overflowing... maybe they should give it a shot? I'm sure areva won't lend their new on site plant for testing, but they really don't have a lot to lose if it doesn't work as planned...

this is one of those situations where they should give this guy and the company what they want and use the solution, no politics, less industry nepotism, pick THE best solution and run with it.

Well, one source of reticence to use new things that people come up with only after the disaster has hit is because if it is tried and doesn't work, then they'd still have the radioactive water to deal with. However, in addition, they'd have the new cleanup material itself to deal with. Because of the contact with the radioactive water, it would become radioactive waste that would have to be decontaminated.

In any disaster, people always come out of the woodwork with these seeming revolutionary fixes. While some of them may actually work, testing them in the face of a crisis is not wise, as introducing fresh unknowns is the exact opposite of what to do during a crisis and can make things worse.

New methods of mediation are to be tested under controlled conditions, not the chaos of a disaster, and especially not when there is a method that works but is on a timescale that seems to be "too slow" or faces logistical hurdles that can be overcome with time.

 

[clancy688]

The document says 130,000 TBq of I-131 and 6,000 TBq of Cs-137. Then, there's a mysterious "Iodine value conversion" before apparently adding the numbers to get 370,000 TBq.

INES Manual, page 5 paragraph 1.4.1, page 15f paragraph 2.2

The mystery behind iodine value conversion is explained there.

http://www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf

 

[mscharisma]

Well, one source of reticence to use new things that people come up with only after the disaster has hit is because if it is tried and doesn't work, then they'd still have the radioactive water to deal with. However, in addition, they'd have the new cleanup material itself to deal with. Because of the contact with the radioactive water, it would become radioactive waste that would have to be decontaminated.

In any disaster, people always come out of the woodwork with these seeming revolutionary fixes. While some of them may actually work, testing them in the face of a crisis is not wise, as introducing fresh unknowns is the exact opposite of what to do during a crisis and can make things worse.

New methods of mediation are to be tested under controlled conditions, not the chaos of a disaster, and especially not when there is a method that works but is on a timescale that seems to be "too slow" or faces logistical hurdles that can be overcome with time.

Would agree that one should proceed with extreme caution to avoid making a bad situation even worse. However, what would keep TEPCO (or anyone) from conducting such a controlled experiment? Time is clearly running out as far as the contaminated water and storage solutions are concerned. While I as a non-technical person lack the understanding of most technical aspects discussed here and elsewhere, I very much miss the Plan B (or C etc.) planning that one would look for from a common sense perspective, especially in a disaster this profound. So why not test alternatives?

 

[thehammer2]

So why not test alternatives?

Oh, I'm definitely not suggesting that they don't test what this guy's developed. Test the hell out of it and do it quickly if possible, just don't do it at any nuclear plant currently going through a severe accident. We're talking long cleanup timeframes, so test it offsite and once we know the new procedure is more effective than what we've got, only then implement it.

 

[Jorge Stolfi]

I am not sure that your statement that the volatile elements would be trapped if the uranium oxide remained solid is correct. My argument doesn't invalidate your guesstimate of 10%, but my guesstimate would be higher.

Indeed, according to the Cristoph Mueller slides posted earlier, once the fuel is completely molten, the radioactive elements that remain in the liquid melt (corium) will produce 30% of the decay heat power that would be produced by the intact fuel; the other 70% of the decay heat power is due to more volatile elements that will end up elsewhere.

Some of that 70% will escape to the atmosphere, some will be washed out by the cooling water, and perhaps some will be deposited inside the reactor or containment in places and forms that cannot be easily washed out. In any case those 70% are a big contamination problem but should not pose much of a heat management problem. Is this correct?

On the other hand the corium will contain many long-lived isotopes which could be a huge health hazard if they were ejected to the atmosphere. While the contribution of an element to the heat production rate is inversely proportional to its half-life (among other things), its potential for health damage is largely independent of it, at least for lifetimes up to a decade or two. So, while the corium keeps 30% of the decay heat production, it may include a larger fraction of the total health damage potentia of the original fuel.

 

[etudiant]

Well, one source of reticence to use new things that people come up with only after the disaster has hit is because if it is tried and doesn't work, then they'd still have the radioactive water to deal with. However, in addition, they'd have the new cleanup material itself to deal with. Because of the contact with the radioactive water, it would become radioactive waste that would have to be decontaminated.

In any disaster, people always come out of the woodwork with these seeming revolutionary fixes. While some of them may actually work, testing them in the face of a crisis is not wise, as introducing fresh unknowns is the exact opposite of what to do during a crisis and can make things worse.

New methods of mediation are to be tested under controlled conditions, not the chaos of a disaster, and especially not when there is a method that works but is on a timescale that seems to be "too slow" or faces logistical hurdles that can be overcome with time.

Well, there are a couple of easily answered questions. notably as how well, if at all, the process works in a salt water environment and how easily it scales.
The test demo used 15 milligrams of material for 100 ml of contaminated water, or 150 grams/ton.
At Fukushima, we have about 100,000 tons of water to deal with, so we need 15,000 kilograms of material.
The claim is the material components are 'easy to obtain and rich in supply' .
To be useful, or at least comparable to the AREVA effort, the new approach must clean up 1000 tons/day of contaminated water. That takes about 1500 kg of material. Can/will Dr Ohta and his partners deliver at that pace?