RADIOISOTOPES

Basin Geographical Features in Rias Coast and Radon Concentration

Hiroshi KOJIMA, Katsuhiro NAGANO, Kazuhiko MIURA, Takeshi HARA, Shiger ...

2005Volume 54Issue 11 Pages 521-529
Published: November 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.521

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To elucidate the meteorological characteristics at a rias coast, the measurement of the radon daughters and aerosols, together with vertical profiles of meteorological elements were performed at the Otsuchi bay in Iwate Prefecture during summer in 1997 and 1998. From the measurement, it has been found that the radon daughter concentration has a typical diurnal variation with a maximum from nighttime to early morning and minimum in daytime. The ratio of maximum to minimum diurnal value is approximately ten. It is inferred from the data of vertical profiles of wind and temperature that the development of thermally stable atmosphere in the early morning leads to high level of radon daughters. It can be said that the development of stable atmosphere is uncommon peculiar feature under the meteorological condition of humid season of summer. It is thought that this phenomenon is closely related with geographical features of rias coast surrounded by low mountains. It is suggested that a geographical inversion, developed in a basin and called as a Cold Lake Climate occurs at a rias coast.

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²²⁸Ra/²²⁶Ra Activity Ratio in River Water in Okutama Area, Wwstern District of Tokyo

Tomoko NAKANO-OHTA, Jun SATO

2005Volume 54Issue 11 Pages 531-540
Published: November 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.531

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The ²²⁸Ra/²²⁶Ra activity ratios obtained by the observations with 3 river waters, 2 hot-spring waters and 12 samples from sedimentary rock occurring in Okutama area, western district of Tokyo, ranged from 1.0 to 2.9, from 0.7 to 0.8 and from 1.2 to 1.7, respectively. The average values were 2.0 ± 0.0₃ for river waters and 1.4 ± 0.1 for sedimentary rocks, suggesting that the activity ratio of ²²⁸Ra/²²⁶Ra in river water tends to be larger than that in the associated sedimentary rocks. The ²²⁸Ra/²²⁶Ra activity ratios in hot-spring waters staying in the deeper aquifer with longer residence time may tend to be smaller than those in river waters with shorter residence time. The ²²⁸Ra/²²⁶Ra activity ratios in river waters showed that the activity ratios tended to decrease after heavier rainfalls than 20 mm/d. The decrease in the ²²⁸Ra/²²⁶Ra activity ratios in river waters suggested that heavy rainfalls forced the deeper underground water with long residence time to discharge into river water.

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Possibility of Application of Assembled Complexes to Disposal of Radioactive Waste Water

Satoru NAKASHIMA

2005Volume 54Issue 11 Pages 541-544
Published: November 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.541

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We succeeded in removing RI from radioactive waste water by synthesizing inclusion compounds of the assembled iron complexes bridged by bipyridine (bpy) or 1, 2-bis (4 pyridyl) ethane (bpa) in the radioactive waste water. The removal of RI was confirmed by 2π-gas-flow counter measurement. 86% of RI was removed in the Fe-bpy-NCS complex, while 48% of RI was removed in the Fe-bpa-NCS complex. Liquid scintillation counter measurement revealed the dependence of the removal ratio on the nuclide, which was attributed to the difference in size and chemical structure of the included radioactive molecules.

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Performance Test in Terms of Energy and Angular Dependence with ISO Photon Radiation on an Ambient and Directional Dose Equivalent Rate Meter

Satoshi MIKAMI

2005Volume 54Issue 11 Pages 545-553
Published: November 15, 2005
Released on J-STAGE: March 01, 2011

DOIhttps://doi.org/10.3769/radioisotopes.54.545

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This paper presents the characteristics of the ambient and directional dose equivalent rate meter, AE133B developed by Applied Engineering Inc., Japan, in terms of variation of response with photon radiation energy and angle of incidence, and dose rate dependence. The resultant response using ISO gamma radiation and narrow spectrum series X-radiation for ambient dose equivalent was found to be within 40% in the combined rated range of photon energy, 30 keV to 1250 keV and angles of radiation incidence, 0°to 60°, and those for directional dose equivalent was within 40% in the combined rated range of 12 keV to 250 keV and angle of radiation incidence, 0°to 75°. These resultant characteristics sufficiently met the requirements of the standard, IEC 60846-second edition. The ambient and directional dose equivalent rate meter was found to have sufficient specifications of energy and angular dependence.

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Transactinide Element Research—Present Status and Perspectives

Yuichiro NAGAME

2005Volume 54Issue 11 Pages 555-567
Published: November 15, 2005
Released on J-STAGE: July 21, 2010

DOIhttps://doi.org/10.3769/radioisotopes.54.555

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Monthly Frequency of the Annual Maximum Absorbed Dose Rate in Air for Environmental γ-radiation in Japan

Naoto FUJINAMI, Tetsuya WATANABE, Takashi MAEDA, Tomonori ARAKI, Kazuh ...

2005Volume 54Issue 11 Pages 569-573
Published: November 15, 2005
Released on J-STAGE: July 21, 2010

DOIhttps://doi.org/10.3769/radioisotopes.54.569

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