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Usui, Toshihide; Takashima, Hideki; Iwasa, Atsutoshi; Hamazaki, Masaaki
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05
Okura, Takehisa; Yamazawa, Hiromi*; Moriizumi, Jun*; Hirao, Shigekazu*; Guo, Q.*; Tojima, Yasunori*; Iida, Takao*
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05
Monitoring network of 
Rn concentration in air which was measured in Beijing, Nagoya, Hegura-jima, Hachijo-jima and Hateruma-jima, as a tracer for long-range transport in East Asia was established. At inland sites, Beijing and Nagoya, high concentrations Rn were measured, at marine sites, Hachijo-jima and Hateruma-jima, Rn concentrations level was very low. Seasonal variations of the Rn concentration show that Rn concentration was the lowest in the summer and the highest in the winter. Diurnal variations were measured at inland sites. At marine sites several-day-cycle variations were measured. It was pointed out by this study that the several-day-cycle variations at Hachijo-jima were dependent on synoptic-scale atmospheric disturbance. Backward trajectory analysis of the relationship between atmospheric Rn concentrations at Hachijo-jima and transport pathway of air mass indicates that atmospheric Rn at Hachijo-jima has much to do with transport pathway of air.
Yoshida, Tadayoshi; Tsujimura, Norio; Yamano, Toshiya*
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05
A neutron survey meter with a ZnS(Ag) scintillator to measure recoil protons was built. The detection probe weighs approx. 2 kg, therefore providing us with true portability. Performance tests exhibited satisfactory neutron dosimetry characteristics at unmoderated or lightly moderated fission neutron fields and in particular work environments at a MOX fuel facility. This new survey meter will augment a routine neutron monitoring inconveniently being carried out by moderator-based neutron survey meters.
Tsujimura, Norio; Yoshida, Tadayoshi; Takada, Chie
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05
To predict how accurately the neutron dosemeters can measure the neutron dose equivalent (rate) in MOX fuel fabrication facility work environments, the calculations of the dose equivalent responses of neutron dosemeters were performed by the spectral folding method. The dosemeters selected included two types of personal dosemeters (a thermoluminescent albedo neutron dosemeter and an electronic neutron dosemeter), three moderator-based neutron survey meters and one special instrument called an 
(10) monitor. The calculations revealed the energy dependences of the responses expected within the entire range of neutron spectral variation observed in neutron fields at workplaces.
Takeyasu, Masanori; Nakano, Masanao; Sumiya, Shuichi; Nemoto, Hiromi*; Kanno, Mitsuhiro*; Kurosawa, Naohiro*
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 4 Pages, 2010/05
The dose to the public at hypothetical accident of nuclear facility is estimated on the basis of the method described in the Japanese meteorological guideline. However, the radioactive decay during atmospheric dispersion of released radionuclide is not considered in the calculation formula in the guideline. Therefore, when the radionuclide of the half life such as a few min is released, the dose may be excessively over-estimated. In this study, the calculation code was developed which could consider the radioactive decay of the released radionuclide and the generation of the product. The dose calculated on the basis of the developed code was compared with that on the basis of the guideline.
Kanai, Katsuta; Kurihara, Osamu
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05
Chest wall thickness (CWT) of the subject is an important modifier to determine the lung burden of inhaled actinides such as Pu isotopes or 
Am through lung counting. CWT prediction equations as a function of biometric indexes have been proposed by many authors based on chest wall measurements made with an ultrasound device. In the present study we derived such equations from CWT data of our subjects and then evaluated their applicability to monitoring with our currently used lung counter, mainly examining the accuracy of determinations of Am, useful as a unique indicator that can be detected in most cases of internal contamination with Pu compounds. The error of the equations obtained was found to be within the range of - 8 mm to + 6 mm against actual CWT values of our subjects, complying with the bias performance criteria for direct measurements. However, further studies might be needed to clarify the effect of the difference in posture on the CWT caused by the modification of the counting geometry made for our lung counter.
Mohammadi, A.; Kinase, Sakae
Proceedings of 3rd Asian and Oceanic Congress on Radiation Protection (AOCRP-3) (CD-ROM), 3 Pages, 2010/05