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Kataoka, Takahiro*; Tokunaga, Rikizo*; Sakoda, Akihiro; Kawabe, Atsushi*; Hanamoto, Katsumi*; Yamaoka, Kiyonori*
Radioisotopes, 61(1), p.1 - 8, 2012/01
Radon inhalation using our radon exposure device activated anti-oxidative function in some organs of mouse. To assess the possibility of its application to veterinary care, healthy dogs and cats with chronic renal failure were inhaled radon at a concentration of 5500 Bq/m
for 30 minutes every 2 days for 30 days. In result, radon inhalation within a relatively long time period significantly decreased the triglyceride level of dogs. On the other hand, some cats increased the volume of drinking water by radon inhalation and the creatinine level in blood of these cats was decreased to normal level. These findings suggest that radon inhalation may have curative properties against chronic renal failure.
Kataoka, Takahiro*; Sakoda, Akihiro*; Yoshimoto, Masaaki*; Toyota, Teruaki*; Yamamoto, Yuki*; Ishimori, Yuu; Hanamoto, Katsumi*; Kawabe, Atsushi*; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*
Radiation Safety Management, 10(1), p.1 - 7, 2011/12
We examined the effect of continuous radon inhalation on acute alcohol-induced oxidative damage of mouse liver and brain. Assay of antioxidative functions indicated that lipid peroxide levels in both the liver and brain of the alcohol-treated mice were significantly higher than those of the saline-treated mice. However, the lipid peroxide level in the liver, but not in the brain, of alcohol-treated mice was significantly decreased by radon inhalation whereas that in the brain of saline-treated mice, but not in the liver of saline-treated mice, was significantly increased by radon inhalation. These findings suggest that radon inhalation inhibits alcohol-induced oxidative damage of liver due to activation of antioxidative functions and that radon inhalation exert only a week effect on the brains in comparing with the livers. They further suggest that alcohol administration protects against oxidative damage of the brain that is induced by radon inhalation.
Kataoka, Takahiro*; Sakoda, Akihiro*; Yoshimoto, Masaaki*; Nakagawa, Shinya*; Toyota, Teruaki*; Nishiyama, Yuichi*; Yamato, Keiko*; Ishimori, Yuu; Kawabe, Atsushi*; Hanamoto, Katsumi*; et al.
Radiation Protection Dosimetry, 146(1-3), p.360 - 363, 2011/07
Times Cited Count：6 Percentile：44.16(Environmental Sciences)Our previous studies showed the possibility that activation of the antioxidative function alleviates various oxidative damages, which are related to lifestyle diseases. Results showed that, low-dose X-ray irradiation activated superoxide dismutase and inhibits oedema following ischaemia-reperfusion. To alleviate ischaemia-reperfusion injury with transplantation, the changes of the antioxidative function in liver graft using low-dose X-ray irradiation immediately after exenteration were examined. Results showed that liver grafts activate the antioxidative function as a result of irradiation. In addition, radon inhalation enhances the antioxidative function in some organs, and alleviates alcohol-induced oxidative damage of mouse liver. Moreover, in order to determine the most effective condition of radon inhalation, mice inhaled radon before or after carbon tetrachloride (CCl
) administration. Results showed that radon inhalation alleviates CCl-induced hepatopathy, especially prior inhalation. It is highly possible that adequate activation of antioxidative functions induced by low-dose irradiation can contribute to preventing or reducing oxidative damages, which are related to lifestyle diseases.
Sakoda, Akihiro*; Ishimori, Yuu; Hanamoto, Katsumi*; Kawabe, Atsushi*; Kataoka, Takahiro*; Nagamatsu, Tomohiro*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(10), p.2013 - 2015, 2010/10
Times Cited Count：1 Percentile：9.96(Chemistry, Inorganic & Nuclear)The performance of IPs has not been studied at temperatures lower than 0
C. In the present study, an IP was irradiated with 
rays emitted from the mineral monazite at temperatures between -80 and 30C to determine its fundamental properties. The IP response as a function of irradiation time was found to be linear, suggesting that the IP works properly at low temperatures. Fading, an effect which should be considered at temperatures of more than 0C, was not observed at -30 and -80C. Furthermore, the fading-corrected PSL value of the IP irradiated at -80C was lower than at other temperatures (30, 5 and -30C). This can be explained by TSL. Since the only intensive TSL peak in the temperature range from -80 to 30C is present at about -43C, some of the electrons trapped at F centers recombine with holes through the process of TSL before the stored radiation image is read out at room temperature.
Sakoda, Akihiro*; Ishimori, Yuu; Kawabe, Atsushi*; Kataoka, Takahiro*; Hanamoto, Katsumi*; Yamaoka, Kiyonori*
Journal of Nuclear Science and Technology, 47(8), p.731 - 738, 2010/08
Times Cited Count：42 Percentile：93.02(Nuclear Science & Technology)This is the first report to provide radiation doses, arising from inhalation of radon itself, in mice and rats. To quantify absorbed doses to organs and tissues in mice, rats, and humans, we computed the behavior of inhaled radon in their bodies on the basis of a physiologically based pharmacokinetic (PBPK) model. It was assumed that radon dissolved in blood entering the gas exchange compartment is transported to any tissue by the blood circulation to be instantaneously distributed according to a tissue/blood partition coefficient. The calculated concentrations of radon in the adipose tissue and red bone marrow following its inhalation were much higher than those in the others, because of the higher partition coefficients. Compared with a previous experimental data for rats and model calculation for humans, the present calculation was proved to be valid. Absorbed dose rates to organs and tissues were estimated to be within the range of 0.04 - 1.4 nGy/(Bq/m
)/day for all the species.
Sakoda, Akihiro*; Hanamoto, Katsumi*; Ishimori, Yuu; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(6), p.1169 - 1172, 2010/06
Times Cited Count：31 Percentile：88.5(Chemistry, Inorganic & Nuclear)The present model represents an improvement on previous models of radon emanation from soil by incorporating soil grain size in addition to moisture. Monte Carlo simulation was employed in the calculation since it was difficult to mathematically express the radon emanation fraction for the present soil model. Grain size is one of the most important factors in describing the properties of soil. Grain size was demonstrated to affect the radon emanation fraction, depending on moisture content. Although the emanation fraction is generally considered to be proportional to grain size, the result of the model calculation suggested that the effect of grain size is not so simple. This study should serve as an initial step toward improving the modeling of this radon emanation.
Sakoda, Akihiro*; Nishiyama, Yuichi*; Hanamoto, Katsumi*; Ishimori, Yuu; Yamamoto, Yuki*; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Applied Radiation and Isotopes, 68(6), p.1180 - 1184, 2010/06
Times Cited Count：53 Percentile：95.3(Chemistry, Inorganic & Nuclear)We examined differences in the radioactive characteristics among the main minerals forming granite materials. Using a non-toxic high-density agent, minerals were separated from rock (granite-gneiss) and soil (weathered granite) samples. The natural radioactivity (
U and 
Ra) and radon emanation fraction of the minerals were then studied by -ray spectrometry. The radon emanation fractions (27-43%) of the minerals from the soil were much higher than those (0.6-4.6%) of the rock minerals. Additionally, the emanation fractions differed greatly among the minerals separated from both the bulk rock and soil. These results were discussed in terms of the differences of surface area and radium distribution in the mineral grains. It was noticeable that a higher emanation fraction than expected for quartz was commonly observed in the rock and soil samples. We then estimated the contribution of each constituent mineral to the total radon exhalation from the bulk samples. The result depended not only on the radon emanation fraction, but also on the Ra activity and the mineral content. Furthermore, using the obtained data, we also discussed the effect of grain size on radon emanation and why this has been reported to vary markedly in previous studies.
Sakoda, Akihiro*; Ishimori, Yuu; Hanamoto, Katsumi*; Kataoka, Takahiro*; Kawabe, Atsushi*; Yamaoka, Kiyonori*
Radiation Measurements, 45(2), p.204 - 210, 2010/02
Times Cited Count：61 Percentile：96.42(Nuclear Science & Technology)Some models have already been developed to explain the effect of moisture content on the radon emanation fraction of soil. For this purpose, "microscopic" soil models, which are easy to deal with mathematically but cannot take grain size into consideration, have been designed. These previous models consist basically of two opposite grain surfaces and pores between the grains. In the present study, in order to study the effect of not only moisture content but also grain size, we present a simple modeling approach based on two "macroscopic" soil models: (1) a single-grain model and (2) a multiple-grain model. The latter model represents a configuration of spherical grains packed in a simple cubic structure. Based on these soil models and general assumptions, the radon emanation fraction was calculated as a function of grain size or moisture content by Monte Carlo simulation. The results for the multiple-grain model show that the radon emanation fraction is markedly increased with grain sizes ranging from 10 to 100 mm and reaches a constant value of 50% when moisture content is 0% and the radium is uniformly distributed on the grain surface. Moreover, a drastic increase is seen at smaller grain sizes with increasing moisture content. From these results, we concluded that the calculation of radon emanation depends greatly on the pore size between a Ra-bearing grain and a neighboring grain. The validity of the model was also evaluated by comparison to experimental data.
Hayashi, Hirokazu; Akabori, Mitsuo; Minato, Kazuo; Mizuguchi, Koji*; Kawabe, Akihiro*; Fujita, Reiko*
Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 75(7), p.528 - 534, 2007/07
Times Cited Count：0 Percentile：0.01(Electrochemistry)The simulation code for the pyrochemical processing of spent nuclear fuels was developed to analyze experimental data, to predict experimental results, and to propose adequate conditions and processes. The Simulation code for Pyrochemical Reprocessing (SPR) is based on calculations of chemical equilibrium and electrochemical reactions. The code also includes the calculations of the current-potential distribution between the electrodes. Some calculations were made to simulate the experimental results on the electro-codeposition process of UO
and PuO. The phenomena of the redox reactions between Pu
and Pu
ions and those between Fe and Fe
ions were theoretically analyzed; these redox reactions cause the low current efficiency in the electro-codeposition process. The calculated current-potential distribution around the cathode corresponds to the observed distribution of the oxide deposited on the cathode.
; Kawabe, Akihiro; ;
JNC TN8400 2001-021, 238 Pages, 2001/03
JNC-TN8400-2001-021.pdf:9.44MB
In plutonium conversion development facility (abbreviated to PCDF) in JNC (Japan Nuclear Cycle Development Institute) Tokai Reprocessing Plant, investigations of producing MOX nuclear fuel by a simplified process have been studied. A study of this process, which is called "Short Process", has been carried out for the purpose of decreasing the production cost of MOX fuel in cooperation with plutonium fuel center in JNC Tokai Works. The purposes for this study are, (1)to decrease the number of equipment by the simplification of our MOX fuel production process (2)to improve the working ratio (3)to stabilize the quality of MOX fuel (4)to decrease the amount of the hold-up of MOX fuel in glove boxes (5)to improve an efficiency of transporting nuclear materials (6)to decrease operating cost In this "short process", it is necessary to mix plutonium nitrate solution and uranium nitrate solution with relatively high accuracy on the assumption that the adjustment of Pu/U ratio is controlled as a liquid state. As a result, the volume of these nitrate solutions has to be measured and transported to another vessel within high accuracy. At first, in fiscal 1999, a mock-up apparatus equipped with airlift systems, which imitated solution-mixing process in PCDF, was designed, made and assembled together. In fiscal 2000, by using this mock-up airlift apparatus, tansferring experiments were carried out both to estimate the accuracy of Pu/U mixing ratio in PCDF operation plant and to confirm characteristics of the airlift pump systems in PCDR The results showed that Pu/U ratio control in PCDF plant could not always satisfy the specifications for MOX fuel. From both the operation data in PCDF and results of our experiments, investigations were carried out for the purpose of improving the accuracy of Pu/U ratio control.Our mock-up airlift apparatus was modified and the accuracy of Pu/U ratio control was reexamined. It was confirmed that Pu/U ratio control by modified airlift ...
Ozawa, Masaki; Kawabe, Akihiro*; Mizuguchi, Koji*; Fujita, Reiko*; Sumida, Yukio*
no journal, ,
no abstracts in English
Ozawa, Masaki; Kawabe, Akihiro*; Mizuguchi, Koji*; Fujita, Reiko*; Sumida, Yukio*
no journal, ,
no abstracts in English
Hayashi, Hirokazu; Akabori, Mitsuo; Minato, Kazuo; Mizuguchi, Koji*; Kawabe, Akihiro*; Fujita, Reiko*
no journal, ,
The simulation code for the pyrochemical processing of spent nuclear fuels was developed to analyze experimental data, to predict experimental results, and to propose adequate conditions and processes. The Simulation code for Pyrochemical Reprocessing (SPR) is based on calculations of chemical equilibrium and electrochemical reactions. The code also includes the calculations of the current-potential distribution between the electrodes. Some calculations were made to simulate the experimental results on the electro-codeposition process of UO and PuO. The phenomena of the redox reactions between Pu and Pu ions and those between Fe and Fe ions were theoretically analyzed; these redox reactions cause the low current efficiency in the electro-codeposition process. The calculated current-potential distribution around the cathode corresponds to the observed distribution of the oxide deposited on the cathode.
