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Name: Iota
Status: other
Grade: other
Country: Canada
Date: April 6, 2011


Question:
Radioactive Water: If you have radioactive water, and distill it, if the water was not radioactive but had a radioactive mineral dissolved in it, will the distilled water, minus that radioactive element, be radioactive or is there a chance the distilled water will be radiation free? Is there any surefire way for removing all radiation from water?


Replies:
It depends on what the radioactive contaminant is, and it depends on how the distillation is carried out. It also depends on your standards for "radiation free."

Part of the problem is that radioactive waste usually contains many different radioactive elements, each with unique chemical properties. Most of the really bad actors, like cobalt, plutonium, cesium, and strontium, do not form compounds with high volatility. So they will not go into the vapor phase, and theoretically will be left behind in the pot in a distillation. In practice, however, distillation involves boiling, which produces aerosols. Some of these may be carried into the collector. Different ways of running the distillation can increase or decrease the extent to which this happens.

In many cases, major proportions of the radioactive contaminants can be removed by ion exchange or reverse osmosis. But what fraction of residue is low enough?

Some contaminants, such as radon and iodine, will not necessarily be removed by a simple distillation of the water. More complex distillations can do better, but exactly what is best to do depends on the specific situation.

Basically, distillation will probably remove a lot of the radioactive contamination from water. Whether or not the distilled water is safe to drink will depend on how much radioactivity is left and what your standards of safety are. Do not forget that all of us are daily exposed to ionizing radiation from natural and man-made sources. Your distilled water will not be "radiation free." But then again, water from a pristine mountain stream is not radiation free either, and it would not have been even before humans discovered radioactivity.

Richard E. Barrans Jr., Ph.D., M.Ed.
Department of Physics and Astronomy


If you have "radioactive" water, it depends upon the amount and the source of the radioactivity. This common candidates would be alpha particles (the nucleus of a helium atom), beta particles (energetic electrons), gamma radiation (high energy electromagnetic radiation) -- and mixtures of these. An additional factor is the chemical form in which the radioactivity is present. This could be numerous chemical elements with various radioactive nuclei.

As well as various compounds. So you are looking at separating various chemical species, with varying radioactivity. You can see that what starts out to be an easy question, has a very complex answer. You cannot just assume the radioactivity comes from some mineral that remains dissolved in the distillation "pot".

In principle you could separate the radioactive mineral from the water, but at a large energy cost. The heat of vaporization of water requires a lot of energy, so even if the chemistry "works on paper" does not mean that it would be feasible on a large scale. Believe me when I say that if a distillation were so simple, it would have been tried a long time ago. It is not an easy solution.

Vince Calder





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