As a result of the Fukushima nuclear accident, some 120,000 cubic meters of radioactive waste water was created in the process of cooling the reactors. The method to be used for the treatment of the enormous amount of water is a technology developed at the University of Helsinki.
A satellite image showing damage after an earthquake and tsunami at the Dai Ichi Power Plant. Photo: DigitalGlobe-Imagery / Flickr.com (Creative Commons).
University of Helsinki chemists have developed the most efficient method for clean radioactive water in nuclear plants. The purification process is based on ion exchangers made from inorganic, solid materials. In simple terms, they have the capability to bind agents in a liquid, which in the case of Fukushima were radioactive.
The ion exchange materials developed at the Kumpula Science Campus by the Laboratory of Radiochemistry in collaboration with the Finnish energy company Fortum are selective, which means that they are able to pick out only the substances that are required from large volumes of liquid.
In practice, ion exchangers used in industrial processes come as granules encased in metal cartridges. When a liquid is driven through the cartridge, radioactive pollutants are bound by the granules.
Ion exchangers have been developed at the University of Helsinki since the early 1980s, and their commercial applications have been in use since the 1990s in several countries, at first in the Finnish nuclear power plant at Loviisa. The inorganic ion exchangers used at Fukushima were developed by Dr. Risto Harjula, Dr. Heikki Leinonen and Professor Jukka Lehto, who also heads the Laboratory of Radiochemistry.
According to Professor Lehto, purification methods based on Finnish ion exchangers are the most advanced in the world. Thanks to its selectiveness, the method allows for a dramatic reduction in the volume of radioactive waste to be disposed compared to other methods, and the remaining water will be sufficiently clean to be discharged into the sea.
“We represent the absolute best in the world in our niche. No other instance in the world has similar knowledge and product selection,” says Professor Lehto.
This article by Kimmo Luukkonen has also been published in Helsinki University News.