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Keeping the dust down

The events inJapanand the way in which the clean up team are dealing with the problem lead me to think about polyacrylamide. It is important from the off set to understand that polyacrylamide and acrylamide are different substances with very different properties. While polyacrylamide is made from acrylamide, good well made polyacrylamide is free of acrylamide. So it is unreasonable in my view to want to outlaw the use of polyacrylamide because the monomer (acrylamide) is toxic.

In the same way, nylon-6,6 (the stuff used for a lady’s tights) is made using cyanide. Hydrogen cyanide is reacted using a nickel catalyst with butadiene to make 1,4-dicyanobutane which is used as a feed stock for making nylon. But I do not think that wearing nylon tights (or a more macho green nylon safety belt as used by people who climb radiomasts or towers) will expose the wearer to any danger of cyanide poisoning.

Sadly some years ago in Swedena tunnel (Hallandsås Tunnel) was being dug, a rock glue which contains acrylamide was used during the construction process. Rhoca-Gil is a rock glue which contains acrylamide and a related substance (N-methylacrylamide). Sadly the monomer leaked out, it caused the deaths of fish and farmyard animals. In addition it was responsible for causing human disease in this case. (http://www.rpaltd.co.uk/documents/acrylamiderrs.pdf)

I hold the view that many monomers are nasty chemicals, and of these acrylamide is one of the nastiest ones (It is a carcinogen and a neurotoxin). But the good news is that the polymer is not able to harm you in the same way as the monomer.

In Japanat the site of the damaged nuclear plant workers have been spraying an antidust agent to stop dust becoming mobile. I have been informed by Prof Ryu Hayano (A Japanese physicist) that kuricoat (http://www.kurita.co.jp/products/kuricoat.html) is being used. One lady inJapan has kindly examined the web site for me and it appears that this product is a water based spray which gives between six and twelve months of dust suppression. Based on these details I suspect that it may be a polyacrylamide product. Such a product is soluble in water and it is known that polyacrylamide does biodegrade.

We need to ask ourselves if keeping the dust suppressed is good for the workforce, one school of thought when dealing with radioactive contamination is to immobilise and fix it. One plutonium chemist I know fromEnglandalways expressed the view that the best thing to do with plutonium contamination in the lab is to paint over it. My reasoning is the greatest threat from plutonium is the internal threat, so fixing it with paint may be the best thing to do. This is the “let sleeping dogs lie” school of thought, I would say that in many cases in chemistry that it is best to let sleeping dogs lie but it is important to take steps to make sure nobody else “wakes the dog”. For example if you find a bottle of a nasty chemical hidden behind a cupboard under the sink (I once made such a discovery) it is best not to open it without finding out how to handle it.

The paint over the plutonium is a method of giving the dog a nice comfortable bed to encourage it to go to sleep. But it is not a final solution to the problem, on the other hand if a bench is contaminated with 32P then painting and then laying a thick sheet of plastic over the bench does offer a solution as this radioisotope has a short half life.

Another use of paint to control radioactivity is the use of paint to stop radon entering a basement if your home is in a high radon area, one of the best things to do to prevent radon entering the house is to paint all the concrete surfaces in the basement and house. The paint film on the concrete will need to be renewed when the paint starts to age. Here the paint is used to provide a barrier which the radon is slow to diffuse through. The radon is given more time to decay in the walls and floor so less enters the air of the house.

But fixing radioactive dust can be an important part of the management of the contamination, by fixing radioactive dust it can provide the workers with more time to take a further action which will prevent the radioactive dust from becoming a threat to the general public and themselves.

A further reason to fix the dust in the site is to prevent non radioactive dust becoming a means for the transport of the radioactivity. If non radioactive dust enters a radioactively contaminated area then the radioactivity can become bonded onto the normal dust. This now radioactive dust could now blow around in the wind and be a threat to society.

A classic example of this is smoking and radon, I know that smoking is a horrible habit which is harmful to health. So is breathing air which contains high levels of radon, while it is not a socially horrible habit it is harmful to health. But smoking in a radon infested place is much much worse for your health, what happens is that the radioactive daughters of radon stick to the smoke particles in the cigarette smoke. These then enter the lungs and stick to your insides. Thus gluing radioactivity into your lungs. So if you live inCornwallthis is another reason to give up smoking or at least making a point of going out of the house before lighting up.

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