Radioactivity Concentration Analysis of Iodine in the Distribution Survey of Radioactive Substances
FY 2011 - FY 2013   The Ministry of Education, Culture, Sports, Science and Technology, and the Secretariat of the Nuclear Regulation Authority

This series of data was created to study if the deposition densities of iodine 131 and iodine 129 are correlated, and if the deposition density of iodine 131 can be derived using the deposition de...
This series of data was created to study if the deposition densities of iodine 131 and iodine 129 are correlated, and if the deposition density of iodine 131 can be derived using the deposition density of iodine 129 using said correlation between iodine 131 and iodine 129.

FY2013 Radioactivity Concentration of Iodine 131 in Soil Sample through the Analysis of Iodine 129 ( Decay correction: June 14, 2011 )
  1. In order to elaborate the map of iodine 131, this data was created in "Establishment of A Comprehension Approach of Long Term Effects by Radioactive Substances Due to Fukushima Daiichi Nuclear Power Plant Accident" lead by the Secretariat of the Nuclear Regulation Authority. This year, the area of analyses for the iodine 129 was expanded for areas where data had been barely obtained and deposition data of iodine 131 was reconstructed.
  2. This data shows radiation (Bq) per unit area (m2) i.e., "Deposition".
  3. In the Second Distribution Survey, a good correlation between iodine 129 and iodine 131 concentrations in soil was observed. In this data, iodine 131 deposition density at each sampling point was derived by multiplying iodine 129 concentrations obtained in this survey and the (iodine 131)/(iodine 129) ratio "9368" (as of June 14, 2011) obtained in the Second Distribution Survey. Note: (iodine131)/(iodine129) ratio should be adjusted when more analyses are performed in the future.
  4. One sample at each sampling point was used for analysis because the analysis of iodine 129 is time consuming. In this data, the average of each sampling point was calculated by the following method.
    A conversion factor was derived as (Deposition density)/(Average deposition density of 5 sampling points) of cesium 137. The average deposition density (Bq/m2) of iodine 131 was calculated by dividing deposition density of iodine 131 by the conversion factor.
  5. Measurement procedure of iodine 129 deposition densities.
    First, soil sample was taken out from the U-8 container and stirred in the plastic bag till being uniform. A part of the soil sample in the plastic bag was taken out and triturated in an agate ball mill to use as a powder sample for analysis. The powder sample was heated up in 1000 degree C and then volatilized radioactive iodine was collected in an alkaline solution. Using a part of the solution, iodine 127 (stable iodine) was measured by a ICP-MS(Agilent 7700 or 8800). Using the leftover trap solution, the radioactive iodine was separated and refined by solvent extraction and back extraction, and then silver iodide (AgI) was made by adding caustic silver. Using the AgI as a target, ratio of iodine 129 atomicity to iodine 127 atomicity (hereafter, (iodine 129)/(iodine 127) ratio ) was measured by AMS (Accelerator Mass Spectrometry). The chemical separation method of iodine was based on the reference-I. The measurement conditions of AMS were based on the reference-II. The radioactivity concentration (Bq/kg) of iodine 129 in the soil sample was derived using radioactivity concentration of iodine 127 and (iodine 129)/(iodine 127) ratio. Considering the weight and volume of the relevant soil sample, iodine 129 deposition densities per a unit area (Bq/m2) was derived. The detection limit was approximately 0.001Bq/m2.
    1. Reference I. Muramatsu, Y., Y. Takada, H. Matsuzaki, S. Yoshida: AMS analysis of 129I in Japanese soil samples collected from background areas far from nuclear facilities. Quaternary Geochronology, 3, 291-297 (2008)
    2. Reference II. Matsuzaki, H.,Y. Muramatsu, K. Kato, M. Yasumoto and C. Nakano. Development of 129I-AMS system at MALT and measurements of 129I concentrations in several Japanese soils. Nuclear Instruments and Methods in Physics Research Section B, 259, 721-726 (2007)
  6. The analysis results show estimated iodine 131 deposition density and measured iodine 131 deposition density in the first distribution survey as reference.
FY2012 Concentration of Iodine 131 in Soil Samples through the Analysis of Iodine 129 ( Decay correction: June 14, 2011 )
  1. In order to elaborate the map of iodine 131, this data was created in "Establishment of A Comprehension Approach of Long Term Effects by Radioactive Substances Due to Fukushima Daiichi Nuclear Power Plant Accident" lead by the Ministry of Education, Culture, Sports, Science and Technology in Japan..
  2. This data shows radiation (Bq) per unit area (m2) i.e., "Deposition" .
  3. In the Second Distribution Survey, a good correlation between iodine 129 and iodine 131 concentrations in soil was observed. In this data, iodine 131 deposition density at each sampling point was derived by multiplying iodine 129 concentrations obtained in this survey and the (iodine 131)/(iodine 129) ratio "9368" obtained in the Second Distribution Survey". Note: (iodine131)/(iodine129) ratio should be adjusted when more analyses are performed in the future.
  4. One sample at each sampling point was used for analysis because the analysis of iodine 129 is time consuming. In this data, the average of each sampling point was calculated by the following method.
    A conversion factor was derived as (Deposition density)/(Average deposition density of 5 sampling points) of cesium 137. The average deposition density (Bq/m2) of iodine 131 was calculated by dividing deposition density of iodine 131 by the conversion factor.
  5. Measurement procedure of iodine 129 deposition densities.
    First, soil sample was taken out from the U-8 container and stirred in the plastic bag till being uniform. A part of the soil sample in the plastic bag was taken out and triturated in an agate ball mill to use as a powder sample for analysis. The powder sample was heated up in 1000 degree C and then volatilized iodine was collected in an alkaline solution. Using a part of the solution, iodine 127 (stable iodine) was measured by a ICP-MS(Agilent 7700). Using the leftover trap solution, the radioactive iodine was separated and refined by solvent extraction and back extraction, and then silver iodide (AgI) was made by adding silver nitrate. Using the AgI as a target, ratio of iodine 129 to iodine 127 (hereafter, (iodine 129)/(iodine 127) ratio ) was measured by AMS (Accelerator Mass Spectrometry). The chemical separation method of iodine was based on the reference-I. The measurement conditions of AMS were based on the reference-II. The radioactivity concentration (Bq/kg) of iodine 129 in the soil sample was derived using radioactivity concentration of iodine 127 and (iodine 129)/(iodine 127) ratio. Considering the weight and volume of the relevant soil sample, iodine 129 deposition densities per a unit area (Bq/m2) was derived. The detection limit was approximately 0.001Bq/m2.
    1. Reference I. Muramatsu, Y., Y. Takada, H. Matsuzaki, S. Yoshida: AMS analysis of 129I in Japanese soil samples collected from background areas far from nuclear facilities. Quaternary Geochronology, 3, 291-297 (2008)
    2. Reference II. Matsuzaki, H.,Y. Muramatsu, K. Kato, M. Yasumoto and C. Nakano. Development of 129I-AMS system at MALT and measurements of 129I concentrations in several Japanese soils. Nuclear Instruments and Methods in Physics Research Section B, 259, 721-726 (2007)
  6. In this database, results for the deposition density of estimated iodine 131 are listed together with those of measured cesium 137 obtained from the first deposition survey as reference.
FY2011 Concentration of Iodine 131 in Soil Samples through the Analysis of Iodine 129 ( Decay correction: June 14, 2011 )
  1. This data was created to study if the deposition densities of iodine 131 and iodine 129 are correlated and then if deposition density of iodine 131 is derived by deposition density of iodine 129 using said correlation between iodine 131 and iodine 129
  2. This data shows radiation (Bq) per unit area (m2) i.e., "Deposition" .
  3. This published data was prepared based on the results of iodine 129 deposition densities obtained in the soil samples that iodine 131 were measured in the first distribution survey.
  4. Measurement procedure of iodine 129 deposition density
    First, soil sample was taken out from the U-8 container and stirred in the plastic bag till being uniform. A part of the soil sample in the plastic bag was taken out and triturated in an agate ball mill to use as a powder sample for analysis. The powder sample was heated up in 1,000 degree C and then volatilized iodine was collected in an alkaline solution. Using a part of the solution, iodine 127 (stable iodine) was measured by a ICP-MS(Agilent 7,700). Using the leftover trap solution, the radioactive iodine was separated and refined by solvent extraction and back extraction, and then silver iodide (AgI) was made by adding caustic silver. Using the AgI as a target, ratio of iodine 129 atomicity to iodine 127 atomicity (hereafter, (iodine 129)/(iodine 127) ratio ) was measured by AMS (Accelerator Mass Spectrometry). The chemical separation method of iodine was based on the reference-II. The measurement conditions of AMS were based on the reference-I. The radioactivity concentration (Bq/kg) of iodine 129 in the soil sample was derived using radioactivity concentration of iodine 127 and (iodine 129)/(iodine 127) ratio. Considering the weight and volume of the relevant soil sample, iodine 129 deposition density per a unit area (Bq/m2) was derived. The detection limit was approximately 0.001 Bq/m2.
    1. Reference I. Matsuzaki, H.,Y. Muramatsu, K. Kato, M. Yasumoto and C. Nakano. Development of 129I-AMS system at MALT and measurements of 129I concentrations in several Japanese soils. Nuclear Instruments and Methods in Physics Research Section B, 259, 721-726 (2007)
    2. Reference II. Muramatsu, Y., Y. Takada, H. Matsuzaki, S. Yoshida: AMS analysis of 129I in Japanese soil samples collected from background areas far from nuclear facilities. Quaternary Geochronology, 3, 291-297 (2008)
  5. Estimation method of deposition density of iodine 131
    The deposition density ratio of (iodine 131)/(iodine 129) was 9368 (as of June 14, 2011), as a result of comparison between iodine 129 deposition measured in this survey and iodine 131 deposition obtained in the first distribution survey. Iodine 131 deposition density was estimated by multiplying iodine 129 deposition density and (iodine131)/(iodine129) ratio. The data show estimated iodine 131 deposition density and measured iodine 131 deposition density in the first distribution survey as reference. Note: (iodine131)/(iodine129) ratio should be adjusted when more analyses are performed in the future.
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FY2011 Concentration of Iodine 131 in Soil Samples through the Analysis of Iodine 129 ( Decay correction: June 14, 2011 )