5 February, 08:35

Fukushima: 20,000 tons of radioactive liquid in the drain system

Fukushima: 20,000 tons of radioactive liquid in the drain system

In the middle of January at one of the reactors of the Fukushima-1 nuclear power plant a hole was discovered through which radioactive water escapes into the ocean. This water is pumped inside the reactor to cool it down, after which it is amassed in large tanks, 1,000 tons each, for a long decontamination period. Damaged communication lines along which water is pumped can be the reason for radioactivity leaks. At present, over 20,000 tons of highly radioactive liquid can be found in the NPP drain system.

Due to serious problems with radioactive water leaks, the issue of reclamation of infested soils was recently ignored both by the local and international media. The area contaminated with radionuclides is about 14,000sq km, which makes 3.6% of Japan's total area. The decontamination process may be accelerated with a method that Professor Vsevolod Kortov from the Ural Federal University offered to his Japanese colleagues. He is a scientist of a world-wide reputation, an academician of the Russian Academy of Natural Sciences, leader of the school of solid-state radiation physics and the author of over 60 inventions. Vsevolod Kortov is Russia's only representative at the international radiation monitoring conference held in Japan every year since 2005. Kortov offers a sorbent based on glauconite, a natural compound.

"Glauconite is a natural sorbent that exists as a mineral in Russia, Kazakhstan and almost all republics of the former Soviet Union. It is not an active sorbent in its original condition but our university's chair of radiochemistry has developed a method of its surface modification. The method consists in a special bake-out regime and consequent chemical treatment which result in forming balls with a high-absorption surface. This method caught the interest of the leaders of the Chiyoda Technol Corporation. We sent 10kg of modified glauconite to Japan. During tests along with six other sorbents, our sample absorbed two thirds of all cesium contained in the specimens. This is about three times the absorptive power of other sorbents, which is an excellent result. We offered Japan the technique of using modified glauconite. When turned into the soil, it absorbs cesium 137 and cesium 134, preventing them from penetrating into the roots of plants. Due to this clean-up, these infested soils may be later used for growing rice again. Glauconite is not a rare mineral, its deposits are most likely to be found in Japan. With the help of our technique, it could be used …"

According to Professor Kortov who participated in the elimination of the Chernobyl accident consequences and who twice visited the 30km zone around the Fukushima-1 nuclear plant, the Japanese approach to decontamination differs from what was used in Chernobyl.

"The decontamination technique around the Fukushima-1 NPP is essentially different from the one used in Chernobyl. Japan chose not to use chemical sorbents and decided to wash everything with clean water under pressure. Later all this water is collected in tanks, similarly to mowed grass. This is very costly, both from the viewpoint of human resources and moneywise. But the Japanese place environmental issues above all. They did not answer my question what they were going to do with those tanks. But when we went through the 20km zone last year we saw huge areas laden with containers filled with radioactive rubbish. It looks like the Japanese decided against burying those containers, which is another difference from Chernobyl where everything was buried in the ground, including machinery. The Japanese fear that the containers may deteriorate in the ground and contaminate underground water. However, I don't understand what they are going to do with those containers. I suppose, they will keep them for 30 years, which is the half-life period of cesium 137 which mostly contaminates all buildings and plants."

In 30 years the radiation level will be considerably reduced. But for 160,000 residents of the affected areas to be able to return to their homes, it is not enough to carry out decontamination effectively, it is required to determine annual exposure figures that allow people to return to radiation-hit areas. The Japanese seem to have ignored the Chernobyl experience, Professor Kortov believes.

"20 millisievert a year is the lower borderline when evacuation of the population begins, according to recommendations of the International Commission on Radiological Protection. It is a very significant problem for the Japanese because thousands of people still live in places of temporary stay. People live in severe conditions posing a huge burden for the budget. For this reason the government means to return people to their homes as soon as possible. I spoke at a press-conference in Fukushima City and offered explanations and some criticism. 20 millisievert a year is the occupational radiation dose for adults. I mean people employed at nuclear power plants 6 hours a day who afterwards go to a clean environment. And here it was planned to send both youngsters and old people to spend 24 hours in such radioactive zones. The results of the research carried out in Ukraine for 25 years after the Chernobyl disaster prove that living even in slightly contaminated areas for long periods of time is more harmful than receiving a one-time large radiation dose. For the second case an effective treatment has been developed but living on territories with even weak radioactivity for decades is extremely dangerous because internal radiation develops, immunity suffers and genetic problems occur. I said that this does not comply with standards accepted in Russia and Europe. But in spite of what I said, I highly respect Japanese experts who are responsible for the elimination of the consequences of the accident. I hope that they manage to achieve the results within the target time frame."

Today no one can give a 100% guarantee against accidents at nuclear power plants or any other industrial facilities. Even the distance of hundreds and thousands of kilometres from nuclear stations is no security guarantee. Accidents of this kind outstep the borders of one state and clearly demonstrate the need for international cooperation in providing nuclear power security.

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