Pollutants on radiocesium contaminated fir and camellia leaves in Northern Fukushima prefecture were measured and decontaminated after the accident at TEPCO's Fukushima Daiichi nuclear power plant. The surface contamination of the leaves of the fir and the camellia leaves was measured by washing by hand with water; the contaminants were then removed by deposition. Leaves that had unfolded more than three years ago were polluted by a high concentration of Cs-137+Cs-134; 7,070±129 Bq/kg in fir and 6,610±195 Bq/kg camellia. Lower position leaves of large camellia plants showed higher levels of radiocesium concentration compared with them of small plants. The radiocesium contamination of leaves decreased to one-fifth (fir) and one-quarter (camellia) by hand rubbing with water before washing. 99.4% of radiocesium contamination from fir leaves and 90.8% of radiocesium contamination from camellia. A large amount of the radiocesium surface contamination on fir and camellia could be removed by rubbing leaf surfaces with water, and the contamination was collected by deposition processing.
Visualization of tritium radioactivity using a melt-on scintillator was studied in order to reduce radioactive waste. The melt-on scintillator immersed glass filter with various tritium radioactivities were measured with an imaging analyzer, a plate reader and a CCD imager. Tritium radioactivities were detected in a plate reader and a CCD imager. 8.6 kBq of tritium was visualized using a CCD imager. Using melt-on scintillator, 3H sample can be visualized directly, therefore, the image of them has a potential to reduce radioactive waste.
Radiocesium pollution of Shinobufuyuna (Brassica rapa) plants and the soil in which they were grown in Fukushima City, was measured using a germanium detector after the accident at TEPCO,s Fukushima Daiichi nuclear power plant. Cs-137 concentrations of soil in which Shinobufuyuna was grown did not decrease significantly in the Miyashiro area from 2011 to 2014. The radiocesium concentrations of the leaf blade without midrib were higher than that of the other parts of the Shinobufuyuna plants. The radiocesium concentration of Shinobufuyuna leaves was 4.2±0.5 Bq/kg in December 2011, and it had increased to 140±6 Bq/kg in March 2012 in the Miyashiro field. The Cs-137 transfer factor to the leaves from soil decreased significantly from 2012 to 2014 in the Miyashiro fields. The reason for the increase in the radiocesium concentration of the leaves is assumed to be the environmental culture conditions during winter in the Miyashiro field.
We proposed a practical protocol for the safe handling of radiation and radioisotopes using the naturally occurring radioactive materials (NORMs) 87Rb and 40K. The protocol can be utilized for the education and training course for radiation handling workers. Rubidium chloride solutions were used for the practice of dilution of unsealed radioisotopes instead of 32P. Rubidium chloride and potassium chloride solid radiation sources were used for the practice of monitoring of the surface contamination using the GM survey meter instead of 32P and 14C. Rubidium chloride solutions were also used for the practice of the contamination check by the smear method. Substitution of the radioisotopes under the Laws Concerning the Prevention from Radiation Hazards due to Radioisotope and others to NORMs can be successfully achieved without notable demerits. We supposed that most of the practice for the safe handling of radioisotopes could be carried out outside a controlled area.
Kanazawa Medical University has a clinical medicine building and another basic medical science building. The RI center is also installed in each building for education and studies. In these, the disposal and drainage facility is established as an outbuilding to a clinical study building, and had access by a drainage pipe to the RI center. In this time, the new medical education building will be constructed, and second floor part will be connected to the clinical study building through the roofed passage onto the disposal and drainage facility. At first, we received hearing with Nuclear Regulation Authority and confirmed that it is not a problem that the roofed passage goes on this facility. Then, we managed construction workers as temporary entrance person at one time and educated them. In addition, we decided to take a monthly report of personal dose of radiation exposure and the entrance record to the controlled area and started construction.