Sunday, June 19, 2011

#Fukushima Contaminated Water Treatment: 75 Tonnes of Water Processed in 5 Hours

Information I found in Chunichi Shinbun says the Toshiba-Kurion-Areva-Hitachi water treatment system at Fukushima managed to process 75 tonnes of highly contaminated water in 5 hours before it was manually shut down.

That's 15 tonnes per hour.

At that pace, it is 360 tonnes per day, and they are pouring 500 tonnes of water per day.

And it also means the contamination level that they expected the Kurion's subsystem to reach in a month was reached in 5 hours. That means the contamination was 144 times more than they had calculated.

(As someone said, it is as if they were reconstituting the nuclear fuel rods.)

I have some questions for the experts on this blog.

Why do they need to do this serially? Kurion's "vessel" (cylinder) is 90 centimeter in diameter, 2.3 meter high. It sure seems like a system meant for much smaller amount of water with much less contamination and the treatment process is to be done very carefully and slowly.

If you pour literally tons of water that needs to be cleaned fast, if you connect the cylinders serially, of course the very first cylinder would take a radioactive hit and the whole system would stop.

Why can't they just fill up a 20-foot container with zeolite, dump water from the top, put the spigot at the bottom, connect a hose to collect water back into a tank, dump the water again until the zeolite in the container gets too dirty? Have several such containers and do it at the same time.

Or for that matter, forget the neat system set up inside the building. Just dump bags of zeolite in the building basements where the contaminated water sits. And forget the idea of circulating the water to cool the reactor. The reactors are cool already because they are devoid of the corium.

Or bring an old oil tanker or two, as many people in Japan and outside have suggested from the beginning, and store the water there until a better water treatment system can be built and tested.

(Oh I forgot. I don't have PhD.)


Anonymous said...

I'm not an expert on the bathymetry off of Fukushima, but it seems unlikely that they could get a large tanker close enough to make using one practical. OTOH, lots of cheapo barges would probably work. Fill those up, tow them to the central Pacific, and scuttle them.

Anonymous said...

>Why can't they just fill up a 20-foot container with zeolite, dump water from the top, put the spigot at the bottom, connect a hose to collect water back into a tank, dump the water again until the zeolite in the container gets too dirty? Have several such containers and do it at the same time.

1) All they have available now, to do something quick, is the Kurion system, which is likely optimized to get as near to optimal use of the zeolite as possible, flowing water through as evenly as possible. Checking Google, Kurion also have a battery of patents on their materials, which can handle multiple radionuclides, so it's possible that Kurion have a monopoly on this tech, which can handle quite physically dirty (oil, salt etc.) contamination in a plug and play system.

2) Zeolite apparently can be processed relatively cheaply and used to filter 'spilt' materials, by burying trenches of zeolite around buried radionuclides.
Perhaps this may be something that ends up being done to help reduce radioactivity releases from the site.

I think the risk of an oil tanker might be unacceptable to them, and it's more likely they'll just keep storing material in tanks on-site, where it's at least semi-contained.

As far as the decontamination system is concerned, the first wtf? moment for me came when I read the test run of the system showed the produced water from the Kurion system was down to 0.003 as radioactive as the input. Obviously the stuff is effective, but pumping through water contaminated with burned and broken fuel rods is obviously a very very different prospect from water that has been polluted very slightly after cooling fuel rods that literally have tiny pinholes in the cladding, which is much more likely type of contamination.

The real wtf? was that the Kurion system is set to stop when radioactivity from the column shows 4mSv/hour. Obviously, there's no way this can handle reconstituted fuel rods, and if they seriously intended to fix water this contaminated, they would have the tanks themselves contained in water or behind lead shielding.

Anonymous said...

Robbie001 sez:

OMG! 15 tons/hr is pathetic the more I hear the worst it gets. I can't believe TEPCO and J/GOV don't have a plan for extended + storage they had to know this could happen. Looks like they were still dreaming everything would work out fine, what a rude awakening.

Ionic exchange cascades are the hallmark of a water polishing system the multiple filters ensure the final product is ultra pure. Unfortunately they aren't polishing a few burst fuel pins worth of contamination. I would guess another reason they use smaller serial tanks is they need to keep the radioactive filter sludge in a manageable volume for future handling. I don't understand why the quad skids weren't broken down into single replaceable modular canisters though. They knew this water was much hotter than anything normally treated. They need the ability to push the filter cascade to its full potential. I think you're right; this system looks totally outclassed by the level of contamination in the soup.

Oh, well so much for FIJISHIMA Unnatural Spring water.

I think a large 20' tank would have the same problem as a quad cascade; one end would get way hotter than the other. The only way around that would be to thoroughly agitate the zeolite column with water pressure so the contamination is equally distributed throughout the column. Foam fractionation would probably help remove a lot of heavy organic contaminates and metal with proper surfactants but then you need to strip the hot fractionate and store it. It would be doable but not at the drop of a hat. I have a feeling it is probably still too much hot sludge to ”safely” handle and store in one blob.

I don't think dumping loose zeolite will sponge up much contamination without proper water flow through the zeolite mass and then there would be the problem of handling tons of loose hot filter sludge some year in the future. If there were too much water flow or the zeolite came in contact with heavy densities of shattered fuel there would be no way of controlling how hot the loose zeolite became. I think under the right conditions the zeolite can absorb a bit more radiation than humans can readily handle or store. The French admitted they’ve never handle anything this contaminated before in such huge volumes and they expressed concern about how they were going to do it. They needed this wastewater plant up and running 6 month before the disaster hit. They could try filling the trenches with zeolite silt fences but I doubt it would be very effective.

Anonymous said...

Thanks for the interesting post, and comments.

Can somebody make a rough estimate of the amount of zeolite required, given the known level of radioactivity of that water: is that kilograms? tons? dozens of tonnes?

Because if large amounts are needed, one cannot put them into the trench without making the water overflow, right?

hire web developer said...

Awesome.. All over the world this technique should be used as to be free from water pollution. Thanks for the post.

Anonymous said...

Yeah, there's desperation here.

Similarly to robbie, I had a moment when I heard that the test run reduced contamination to 0.3% of input water contamination. 99.7% cleaned. Very impressive, but likely to be ineffective unless it can absorb 10's of fuel rods worth of radioactivity, without significant human intervention.

The fact that we are dealing with 1000s of tons of water showing multiple Sv worth of activity, versus the mSv maximums for the columns show us that the system likely isn't workable right now.

Where is the limitation though? Is it

1) contractual, in that the columns are only *allowed* to get to a certain amount of radioactivity, or

2) is it that the zeolite breaks down at a certain point, or

3) is it due to handling limitations in deference to the humans that have to replace, store and reprocess the contaminated columns?

Anonymous said...

Robbie001 sez:

@ Anon 7:58

In my opinion #3 is the most likely candidate with #2 a big possiblity. AREVA was very clear that they had never handle sludge 1Sv and above in such large volumes. While Zeolite is supposed to have a durable crystalline structure this many not be true in the presence of overwhelming radiation bombardment gamma induced atomic displacement is a very real possibility.

Here is an old ORNL document on using zeolite for radiation decontamination. It has a lot of specifics and lessons learned.

A Survey: Utilization of Zeolites for the Removal of Radioactivity ...

During fuel reprocessing operations the entire process occurs in automated "Canyons" that never see humans because of the radiation flux involved. I imagine a full melt down/out creates as much heavy contamination as the UREX/PUREX raffination process.

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