Radioactivity and Air Dose Rate
（2014）
ＱHow has the distribution of radioactive material been investigated?
ＡIn order to investigate species, concentrations, and depth distributions of radioactive nuclides deposited in soil, appropriate methods for investigation have been applied according to the purpose and situation.
◆ Measurement of amounts of deposition:
Investigation of species and deposition quantities of radioactive nuclides in soil surface.
【Model 1】 Analysis in laboratory after taking samples
Radioactive nuclides are analyzed using germanium semiconductor detectors in a laboratory.
Merite…Not only the amount of deposited nuclides but also their chemical states and soil properties can be obtained.
Fig.1 Radioactive nuclides analysis with germanium semiconductor detectors in a laboratory
【Model 2】 Field measurement using portable germanium semiconductor detectors
Merite…There is no need to take and carry samples. Averaged values of deposited amounts of radioactive materials can be obtained at each measuring spot.
Fig.2 On-site measurement using a portable germanium semiconductor detector
◆ Investigation of depth distribution:
Depth distribution and migration behavior of radioactive cesium in soil are investigated.
・soil is taken at every 0.5～several cm depth, paying attention not to mix the soil at different depth.
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Fig.3 Sampling using a scraper plate
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Fig.4 Relatioshiop between concentration of 137Cs and depth
(The figure was made by JAEA based on results obtained in work for the Nuclear Regulatory Agency in 2014.)