In the present study, the reduction of PtCl62− ions and subsequent formation of Pt particles were examined for a few tens keV EB irradiation of PtCl62− ion solution in the presence of 1 - 20 wt% ethanol as an OH radical scavenger. As a result, the reduction of PtCl62− ions proceeded in whole solution by irradiating only the topmost surface layer of the solution, and these Pt particles with sizes of 2 - 5 nm would be produced as primary particles through reduction of PtCl62− ions. Moreover, these Pt particles were observed to have hydrogen dissociation activity and oxidation activity.
Monazite radiation source (2.5mmΦ) proved to be useful as a radiation source of cloud chamber without the dispersion of powder or its adhesion because of a sintered body. After the track appeared within one minute after having put the petri dish on the dry ice, the number increased rapidly followed by the tendency to decrease gradually after that. The tracks can be observed for about 20 minutes after cooled with dry ice. The size of dry ice should be chosen to enter the inside of the bottom edge of the petri dish. The same number of tracks as using conventional mantle radiation source was obtained by utilizing 3 pieces of monazite sintered body separated mutually by about 7.5mm. Hence the petri dish-type cloud chamber with the monazite sintered body as radiation source revealed to make the observation of track easy and prompt.
The influence of atmospheric 14CO2 was evaluated on the determination of biogenic carbon ratios in industrial flue gases using accelerated mass spectrometry(AMS). Bioethanol, n-hexane, and their mixtures were combusted with a four-stroke engine, and 14CO2 in exhaust gases was analyzed by AMS. The experimental biogenic carbon ratio determined by ASTM D6866 method was 1.2 times higher than the theoretical value of mixed fuel containing 3.18% biogenic carbons. In general, the influence of atmospheric 14CO2 taken in combustion gases is neglected. It seems that the error cannot be neglected under international trading of emission allowances, where a large amount of carbons in the fuel were evaluated. The experimental value became to be the theoretical value by subtracting the amount of atmospheric 14C from that of the samples. As the contents of biofuel increased, the experimental biogenic carbon ratios reached the theoretical values and the influence of atmospheric 14CO2 decreased. We recommend that the influence of atmospheric 14CO2 should be corrected when fuel samples contain low amounts of 14C.
Average adult Japanese male(JM-103) and female (JF-103) voxel (lume pi) phantoms newly constructed at the Japan Atomic Energy Agency (JAEA) have average characteristics of body sizes and organ masses in adult Japanese. In JM-103 and JF-103, several organs and tissues were newly modeled for dose assessments based on tissue weighting factors of the 2007 Recommendations of the International Commission on Radiological Protection(ICRP). In this study, SAFs for thyroid, stomach, lungs and lymphatic nodes of JM-103 and JF-103 phantoms were calculated, and were compared with those of other adult Japanese phantoms based on individual medical images. In most cases, differences in SAFs between JM-103, JF-103 and other phantoms were about several tens percent, and was mainly attributed to mass differences of organs, tissues and contents. Therefore, it was concluded that SAFs of JM-103 and JF-103 represent those of average adult Japanese and that the two phantoms are applied to dose assessment for average adult Japanese on the basis of the 2007 Recommendations.
After the accident of Fukushima Daiichi Nuclear Power Plant, radioactivity of fruit trees grown at an experimental farm of Nishi-Tokyo City in Tokyo, which was located about 230km away from the power plant, was measured. Each organ of Japanese apricot and peach trees was taken at harvesting stage, respectively, and the radioactivity of 134Cs and 137Cs was measured. Although radioactivity of orchard soil and tree each organ were low generally, that of bark sampled from 3-old-year branch was as high as 1570Bq/kg −dry weight. The total radioactivity of 134Cs and 137Cs in edible portion was far lower than that of the regulation level.
Paddy field was decontaminated for radioactive caesium by removal of surface soil in Fukushima, after about one month of Fukushima Daiichi nuclear disaster. The radioactivity in the soil was decreased by 50% by removal of surface soil. Removed soil was 5kg/m2 in dry weight, 6L/m2 in volume and 0.6cm in depth. Removal of the only surface of the contaminated soil was effective for decontamination without the decline of the soil productivity.
The Oklo uranium ore in the Francevillian basin at the Republic of Gabon is known as a fossil of natural fission reactor, because large-scaled fission chain reactions spontaneously occurred in the ore two billion years ago. It is of major concern to characterize the properties of nuclear reactors and to investigate the behavior of fission products in and around the reactors. In this review, geological and physic-chemical characteristics of the Oklo natural fission reactor and its implication for radioactive waste disposal are shown.
Giving an overview of the high intensity proton accelerator facility, J-PARC, which has started its user program since December 2008, the neutron source as the major user facility is described. Stressing an advancement of J-PARC pulse neutron source, in particular, important characteristic neutron performance and present situation in implementation of neutron instruments, which maximizes the neutron source performance, are addressed along with recent prominent scientific output. User operation condition in terms of proton beam power just before the devastating earthquake events on March 11, 2011, is touched upon briefly as an record. Showing damage to J-PARC facility from the earthquake, current recovering work as well as the operation schedule is described. In addition to last two years’ experience in user program, a plan to reach the 1MW power of the primary goal of J-PARC is shown.