A research group led by Professor Masahiko Matsukata of Waseda University has succeeded in developing a new technology for treating (reducing volume) radioactively contaminated soil by applying high-pressure cleaning technology.It is expected to contribute to the promotion of intermediate storage of decontaminated soil produced during decontamination work in radioactively contaminated areas.
After the accident at the Fukushima Daiichi Nuclear Power Station, the amount of decontaminated soil generated from the decontamination work of radioactively contaminated soil is currently estimated to be more than 2 million cubic meters.However, the conventional radioactively contaminated soil treatment method uses a large amount of heat energy and chemicals and is not economical, and the development of a technology capable of treating a large amount of contaminated soil has been awaited.
With the technology developed this time, soil is sucked into the inside of the pipe of the device (about 50 mm in diameter), and the soil is washed by the turbulent flow generated by the high-pressure jet.Clay minerals adsorbing radioactive cesium are selectively recovered from the contaminated soil crushed by high-pressure washing through the classification and separation treatment provided in the subsequent stage, separated into washed soil and concentrated soil, and then dehydrated. ..
In the field (Kanagawa, Fukushima) test, contaminated soil mainly composed of forest-derived cohesive soil (radioactive substance concentration 7500 to 4 Bq (becquerel) / kg) was targeted.As a result, the radioactive substance concentration (1700-2200Bq / kg, average 5200Bq / kg) of the sieve-recovered soil after the cleaning treatment decreased to 3800-18% (average 29%) of the original soil.The soil recovery rate was 24-46% (74% on average).
In addition, the concentration of radioactive substances in the recovered soil was approximately 5000 Bq / kg or less, and it was found that it could be reused for construction embankment materials because of its sufficient ground strength, and good effects and effectiveness were confirmed in field tests.Furthermore, the processing cost is estimated to be 15 to 35% of the prior art.
In the future, it aims to improve the crushing effect of cohesive soil, reduce the concentration of radioactive substances, and improve the volume reduction rate by optimizing the classification and separation technology.Another issue is the characterization (characteristic evaluation) of soil organic matter and the development of an efficient separation treatment method.
