A simple Monte Carlo computational technique was developed to simulate general circulation of222Rn in the troposphere between 30° and 60° North. Fitting the calculated results to previously published observed profiles, averaged vertical eddy diffusion coefficients were derived, along with exhalation rate values of 1.5 and 1.0 atoms/cm2⋅s for summer (June-August) and winter (December-February), respectively. To access the validity of the method provided by the present report, the calculated results were compared with a number of experimental measurements of other researchers. Contribution of222Rn originated in the Eurasian continent to the Japan Islands was calculated as an example of applications.
TBP is used as an extraction solvent in nuclear fuel reprocessing. Part of the TBP is degraded by radiation, giving DBP and other minor compounds. Although these degradation products cause various problems in the reprocessing, their behavior has not been clarified sufficiently due to difficulties in chemical analysis. Therefore, we carried out quantitative and chemical state analysis of DBP using31P NMR. We found that the concentration of DBP in TBP can be determined from the peak area without calibration. Then, the chemical state of DBP in solvent wash solutions was analyzed using chemical shift values and it was found that washing causes dissociation of DBP. Tetrametylammonium ion was observed to have a weak intermolecular interaction with DBP- ion. The spectra of Zr-DBP complex indicate that there are four types of bondings which lead to the formation of polymers. All the results confirm the usefulness of31P NMR for analysis of TBP degradation products.
A method for accumulation of99Tc in seawater has been developed. Technetium tracer in +VII oxidation state was added to the seawater together with reducing agent, potassium pyrosulfite, and coprecipitation agent, ferric chloride. After reduction of TC (VII) at pH 4, Tc (IV) was coprecipitated as iron hydroxide by addition of sodium hydroxide to pH 9. The reduction and coprecipitation was quantitative and overall recovery of Tc was more than 98%. The green color of iron precipitate formed at pH 9 suggested that TC (VII) as well as ferric ion was reduced under this condition. Adsorption of Tc (IV), however, was poor for iron hydroxide which was prepared in advance indicating active surface of freshly precipitated iron hydroxide is necessary for quantitative recovery of Tc (IV) . A repeating coprecipitation technique was examined for enrichment of Tc in seawater that the same iron was used repeatedly as coprecipitater. After separation of iron hydroxide with Tc (IV) from supernatant, the precipitate was dissolved by addition of acid and then new seawater which contained reducing agent and Tc (VII) was added. Reduction and coprecipitation was again carried out. Good recovery was attained for 7 repeats. The proposed repeating coprecipitation technique was applicable to a large amount of seawater without increasing the amount of iron hydroxide which is subjected to radiochemical analysis.
We have developed a personal computer system for data processing for the control of unsealed radioactive materials. The system is capable of automatical book-making of acceptance, storage, use and disposal of radioactive materials, and of summing up the amount of accepted, stored and used radioactive materials by only input of individual records. This system helps not only increase efficiency of the booking but also grasp the flow of radioactive materials with ease.
Using phantom images, the adaptation of texture analysis was evaluated in analyzing the scintigrams. Prior to analyse the scintigrams, image data acquisition and preprocessing to degrade statistical noise of pixel counts must be performed. Feature parameters which represent RI distribution should be selected on texture analysis of the scintigrams. Using the feature parameters extracted from probability of pixel counts, the more ununiformity became in RI distribution, the less energy became, but mean, variance, skew and entropy became larger values. When discriminant analysis was done using the textural features, ratio of correlation was 0.998, and accuracy of classification on phantom images which were difficult to be classified visually became 58-83%. The textural features was estimated to be useful quantitative data, when the scintigrams was read visually.
The relation between the blood clearance and hepatic uptake of99mTc-phytate (99mTc-P) and the severity of hepatic injury was investigated by using the dogs induced hepatic injury with carbon tetrachloride (CCl4), D-galactosamine (GalN), α-naphthylisothiocyanate (ANIT) or DL-ethionine (EthN) . After the administration of hepatotoxins, serum GPT activity increased and the blood clearance rate of99mTc-P and the hepatic uptake ratio of99mTc-P decreased with the increase of dose level. The degree of increase in serum GPT activity compared with the control value was in the order: GalN>CCl4>ANIT≅EthN, the degree of decrease in the blood clearance rate of99mTc-P was in the order: GalN>CCl4>ANIT>EthN, and the degree of decrease in the hepatic uptake ratio of99mTc-P was in the order: GalN>CCl4>ANIT≅EthN. These results suggest that the disorder in the hepatocytes may be one of causes for inducing the decrease in the hepatic uptake of99mTc-P, and the consequence of this decrease may induce the decrease in the blood clearance of99mTc-P.
A simple and reliable method for determination of222Rn in natural water has been developed by using gamma ray spectrometric measurement and a sample container particular designed. Samples were directly measured by a Ge detector coupled with the multichannel pulse height analyzer. The activities of222Rn were determined by the area of 352 keV photopeak of214Pb. At the same time, in order to evaluate the accuracy of this method, the activity of222Rn in the same water sample extracted by organic solvent was measured by liquid scintillation counting (LSC) method. The observed activity of222Rn measured by our method agreed with that by LSC method.