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Japanese Scientists Get Creative With Nuclear Contamination Clean-Up

Sunflowers that clean up radioactive caesium in the soil? Powders that extract radioactive caesium in water? Japanese scientists get creative!

| April 23, 2011 | Features

  • Scientist says he can clean up radioactive water 20 times faster.
  • Aerospace experts grow sunflowers to draw up radiation from the soil.

AsianScientist (Apr. 23, 2011) - Sunflowers that clean up radioactive caesium in the soil? Powders that extract radioactive caesium in the water?

On March 11 this year, a deadly 9.0 earthquake and tsunami struck North-east Japan and left close to 30,000 people either dead or missing. In the following devastation, the nearby Fukushima Dai-ichi nuclear power plant became flooded and lost its power supply. Subsequently, overheating and partial meltdown of its reactors led to intense levels of radiation in the reactor buildings, making it impossible for human rescue workers to enter the area. In lieu of humans, a pair of remote-controlled "Packbots" were deployed to assess the damage.

The contaminated water and soil around the reactor now pose a major obstacle towards repair efforts and the ultimate goal of a cold shutdown. To deal with the growing contamination around the site, two Japanese scientists have proposed unusual solutions to the problem.

Decontamination Of Toxic Water

On Tuesday this week, workers began removing highly radioactive water from one of the reactors, for it to be treated and recycled as coolant fluid by French nuclear-engineering firm Areva.

Now, a Japanese chemist is telling the Wall Street Journal that he has developed a powdery substance which can decontaminate the toxic water 20 times faster than Areva's method.

Tomihisa Ohta, a professor at Kanazawa University’s graduate school of natural science and technology, says his compound, made up of natural minerals and chemicals, would be able to treat 1,000 tons of water in an hour. Currently, Areva’s treatment system is able to remove radioactive material from 50 tons of water an hour.

Ohta developed his technology in collaboration with Kumaken Kougyou Co., a pollution cleanup company in Akita Prefecture.

Using a similar compound to those that decontaminate water laced with industrial and metallic pollutants, Ohta modified his to target heavy metals like magnesium, iron and cobalt. These metals would complement the radioactive isotopes of iodine, caesium, strontium and plutonium. Due to patent reasons, he declined comment on the exact structure, but said the material was easily obtained in large amounts.

Ohta's powder would be used to capture and precipitate the radioactive material into a heap that can be easily removed.

Before and after treatment
In experiments, scientists added 15 milligrams of powder to 100 milliliters of water containing non-radioactive caesium at a density of 1-10 parts per million (ppm). Estimates of radioactive caesium contamination at Fukushima Dai-ichi are about 10 ppm. (Source: Tomihisa Ohta/WSJ)

While promising, the technology has never been used in industrial applications, nor tested with radioactive caesium. However, Ohta expressed confidence that his compound would work identically on radioactive caesium because of their similar chemical structures.

About a week ago, Ohta reached out to the Japanese government and Fukushima Daiichi operator, Tokyo Electric Power Company (TEPCO), and offered his solution to the water contamination.

“I never imagined that our product could be used in this kind of way. I had never thought about nuclear pollution,” said Ohta, whose research focuses on environmental pollution.

Sunflowers To Decontaminate Toxic Soil

In a separate effort, a group from the Japan Aerospace Exploration Agency group led by Prof. Masamichi Yamashita are planning to grow sunflowers around the nuclear plant to remove soil contamination of caesium.

Sunflowers near Chernobyl
After the 1986 Chernobyl nuclear disaster, sunflowers and rape blossoms were used to decontaminate soil in Ukraine.

The researchers believe growing sunflowers will remove the radioactive caesium in the ground. Radioactive caesium is similar to kalium, a commonly used fertilizer. If kalium is not present, sunflowers will absorb caesium instead.

Yamashita's team plans to remove the harvested sunflowers through burning, so that the radioactive caesium could be dispersed in smoke instead of requiring storage.

Alternatively, the researchers are also considering using hyperthermophilic aerobic bacteria to decompose the plants. The decomposing process will reduce the sunflowers to about 1 percent of their previous volume, which will slash the amount of radioactive waste that needs to be disposed.

The group has gathered about 300 kilograms of sunflower seeds, and have invited residents and high school students to sow sunflower seeds in the 30-kilometer region around the Fukushima plant. Already, Kanagawa prefectural Hiratsuka Agricultural High School has agreed to plant the seeds on their school grounds.

Thailand, a major producer of sunflower seeds, has also been invited to cooperate in this project.

"We're still in the process of planning for the decomposition facility and some other things. Looking toward the autumn harvest, we'd like as many people as possible to join the project," Yamashita said.

The team also hopes that the sunflower will become a symbol of recovery in the areas affected by the nuclear crisis. For details about the project (in Japanese), see:

Related Articles:
MIT Head of Nuclear Science & Engineering Comments On Fukushima & Nuclear Energy.
Japan May Be “Sinking” Due To Earthquake Damage.
Japan’s Nuclear Crisis: Are There Serious Health Implications?
APEC Secretariat Offers Condolences And Solidarity To Japan.


Source: The Daily Yomiuri and The Wall Street Journal .
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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