nuclear-news

To cleanup some radioactive fallout!

There are two  main problems in whatever decontamination techniques used:  wash off and scrap up techniques, or phytoremediation:

80% of the Fukushima prefecture land surface is forested mountains, forested mountains which you can neither wash off and scrap up nor phytoremediate.

Forested mountains from which the accumulated contamination ruissels down or flies down with wind and rain to the low land living areas which had been previouly decontaminated, some places have already been decomtaminated up to five times, always the contamination coming back up to the pre-decontamination level.

To decontaminate well and forever you would have to cut down those mountain forests, which is a huge surface to be cut down, a gigantic impossible work, which would as an immediate effect spread a lot of the accumulated various radionuclides and make the radiation level jump high everywhere.

With either of those techniques you quickly end up with a huge quantity of contaminated waste, which accumulates quickly and for which there is no real valid solution for disposal. To reduce its volume by incineration is still re-scattering radionuclides into the environment, as there is no incinerator filter capable of blocking 100% of all radionuclides nanoparticles.

Obviously, the cleanup process is much more involved than this, but you can imagine how difficult it is to keep all that radioactive dust from getting into everything. Phil Broughton is a treasure trove of stories and information. But, if you follow his blog, you’ll learn that he takes the decontamination process very seriously. Something a graduate student learned the hard way when they made a poorly-thought out April Fool’s prank. Phil had this to say about the tremendous task of nuclear cleanup:

…everything exposed to air, everything that rain water might wash over, ALL SURFACE WATER, must be assumed to be contaminated. Want to use that car? Wash it down because it’s got a crust of radioactive crap on it, and if you try to drive it, you just climbed inside your own moving irradiator box.

This is the hard part of fallout decon[tamination] and radioactive waste in general. Nothing makes it stop being radioactive other than time, and human attention spans and lifespans are somewhat incompatible with this. Not living in the higher dose world its very hard to contemplate the “I accept this dose for me, my children, and generations to come” when planning reconstruction.

A while ago, I did a couple of comics about how plants (including tumbleweeds) were being used to help clean up radioactive material. Here’s Phil again:

Fungi, in fact, do amazing work sucking fallout products out of the soils. Instead of having roots, their hyphae draw nutrients out of a very shallow layer and do it quickly. This is also good because fallout actually doesn’t penetrate all that deep below the surface of the soil. One of the ways we monitor how much radioactive material is left in the environment is by sampling the mushrooms that grow and plotting it’s drop off following an event. You may discover that there are new sources contributing to the environment which is to say the event isn’t over yet as there’s clearly a continuing release. You can also do detoxification this way by planting, harvesting, repeat until whatever your crop is isn’t showing any uptake of materials anymore.

Of course other parts of the environment are running on different clocks. It will take quite a while for contamination to get to the ground water and then for the groundwater to be sampled by plants that can tap that deep. Annoyingly, fungi and grasses might detoxify the upper layer of soil within a decade only to have the deep tapping trees pull it up from the groundwater and recontaminate the upper layer a decade after that with their now radioactive falling leaves.

After I drew the phytoremediation comics, the number one question asked by readers was: “So, what happens with the plants after they’ve absorbed the radioactive elements?” Apparently, it’s a very real problem that cleanup crews have to work with. Here’s what Kathryn Higley said when I asked her about the sunflowers being planted at Fukushima:

I’ve looked at the discussions on sunflowers and other phytoremediation techniques. From what I’ve read, they are able to capture the ‘low hanging fruit’, but they lose effectiveness after a couple of croppings/harvesting. This is because the residual material is more strongly attached to soil particles (such as clay minerals). That being said, phytoremediation is a relatively low tech solution. The challenge is then what do you do with the contaminated biomass? When I went to Fukushima you could see large ‘super sacks’ of contaminated vegetation just sitting on the side of the road (see photo below). These large bags have a limited lifespan (~5 years) before they degrade due to UV exposure and all your stored material starts being blown around by wind.

http://www.popsci.com/fallout-guy-part-12

May 1, 2016 Posted by dunrenard | Fukushima 2016 | Contaminated Waste, decontamination, Disaster, Fukushima continuing, Fukushima Daiichi, s s | Leave a comment