The oxidation of americium(III) with sodium bismuthate has been investigated in a nitric acid solution. The lower the acidity,
the more rapidly the oxidation of americium(III) to americium(VI) proceeds, especially at higher temperatures. Based on this
finding, a procedure was developed to oxidize americium(III) completely at low concentrations. The americium(VI) free from
the excess oxidant has been found to be stable only at 0°C, irrespective of the acidity, but to be more unstable at the temperature
higher than 10°C, especially at lower acidities.
Authors:K. Masumoto, M. Hara, D. Hasegawa, E. Iino, and M. Yagi
The internal standard method coupled with the standard addition method has been applied to photon activation analysis and proton activation analysis of minor elements and trace impurities in various types of iron and steel samples issued by the Iron and Steel Institute of Japan (ISIJ). Samples and standard addition samples were once dissolved to mix homogeneously, an internal standard and elements to be determined and solidified as a silica-gel to make a similar matrix composition and geometry. Cerium and yttrium were used as an internal standard in photon and proton activation, respectively. In photon activation, 20 MeV electron beam was used for bremsstrahlung irradiation to reduce matrix activity and nuclear interference reactions, and the results were compared with those of 30 MeV irradiation. In proton activation, iron was removed by the MIBK extraction method after dissolving samples to reduce the radioactivity of56Co from iron via56Fe(p,n)56Co reaction. The results of proton and photon activation analysis were in good agreement with the standard values of ISIJ.
Authors:N. Hirose, N. Tsuyuzaki, H. Yamamot, T. Mitsugashira, and M. Hara
A random pulse and probability generator (RPG) has been developed utilizing the detection technique of alpha-particles as the random signal source. The collection technique for 222Rn emanated from natural uranium ore was examined for preparing highly pure 210Pb-210Po as an alpha source for RPG. The yield with a trap refrigerated by liquid nitrogen was observed to be above 99% for 222Rn collection.
Authors:T. Mitsugashira, M. Hara, P. Kim, K. Nakashima, and K. Nakayama
Uranium and thorium isotopes were determined in highly pure aluminum for LSI fabrication by alpha-spectrometry utilizing natural 147Sm as an inner standard. Daughter nuclides in natural decay series are found in an enrichment state from radioactive equilibrium. Unexpected contamination that had a ground water origin was supposed to explain the enrichment. This finding suggests strongly that alpha-spectrometry is still quite an important technique to evaluate soft-error probability for modern memory device materials since highly sensitive instrumental analysis such as ICP-MS is not sensitive enough to short-lived alpha-emitters.
Authors:O. B. Egorov, M. J. O’Hara, and J. W. Grate
A fully automated analysis procedure and instrument for the measurement of total 99Tc in aged nuclear waste has been developed. The overall analysis approach is based on a fully automated wet radiochemical analysis method. Microwave-assisted sample oxidation is used prior to a chemical separation step in order to oxidize all of the non-pertechnetate species to pertechnetate. Separation of the pertechnetate from interfering radioactive and stable matrix species is carried out using an anion-exchange column. The separated 99Tc is quantified using a flow-through solid cell scintillation detector. The instrument is capable of an analysis time of <13 minute per sample with a detection limit of 2000 dpm/ml. Nuclear waste samples from the Hanford site with a high content of non-pertechnetate species were successfully analyzed using this method.
Authors:A. Ikeda, T. Suzuki, M. Aida, Y. Fujii, T. Mitsugashira, M. Hara, and M. Ozawa
In order to develop the partitioning-transmutation system for the reduction of high-level radioactive wastes, the group and mutual separation of actinides and rare earth elements in spent fuels is required. In the present work, a chromatographic separation of trivalent actinides (Am and Cm) and rare earth elements was examined in hydrochloric acid/methanol mixed solvents by using a pyridine resin embedded in high-porous silica beads. In a 70 vol% hydrochloric acid (11.7 mol HCl/dm3)/30 vol% methanol mixed solvent, the elution curves of the trivalent actinides were separated completely from those of rare earth elements at room temperature. The present paper discusses the separation behavior of trivalent actinides and rare earth elements as a function of flow rate, temperature and solvent compositions.
Authors:M. Yagi, Y. Shiokawa, S. Suzuki, M. Hara, I. Satoh, K. Masumoto, and T. Mitsugashira
Neutron emission from the d-d nuclear fusion reaction, D/d,n/3He, in and on titanium metals /titanium sponge and the mixture of titanium powder/ trapped deuterium at about 1 atm has been ascertained by using a high resolution liquid scintillation detector. The neutron emissions from 11 samples which were provided under wide varieties of conditions were measured by temperature change in the range of liquid nitrogen temperature to 350 °C. As a result, it was proved that the neutron emission observed can be divided into two types, such as cooling and heating, by the evolved conditions. Moreover, by estimating the neutron emission efficiencies of samples, it was suggested that the neutron emission reactions are closely related to the deuterium trapped in the surface of titanium metal.
Authors:M. Yagi, T. Mitsugashira, I. Satoh, M. Hara, Y. Shiokawa, K. Inoue, K. Masumoto, and S. Suzuki
As a new fact, the neutron emission from the d-d nuclear fusion reaction in a SiO2–D2 system has been confirmed as well as that in the Ti–D2 system. By using a liquid scintillation detector, the neutron emissions from 8 sample materials consisted of SiO2, in which a small amount of deuterium was adsorbed chemically on the surface layer, were measured in the range of temperature between liquid nitrogen temperature and 400 °C. As a result, it was demonstrated that the neutron-emission reactions take place predominantly on the surface layer of sample material.
Authors:T. Mitsugashira, M. Hara, Y. Suzuki, M. Watanabe, S. Hirai, Y. Okada, and A. Mori
Coprecipitation methods with SmF3 and BaSO4 were developed in order to evaluate the radioequilibrium of natural decay nuclides series in high purity silica and lead.
The present study revealed that228Th,230Th, and231Pa in silica and210Po, probably210Pb, in lead were enriched in much higher concentrations than their precursor nuclides.
Authors:T. Suzuki, M. Aida, Y. Ban, Y. Fujii, M. Hara, and T. Mitsugashira
The separation of trivalent actinides and lanthanides was studied by using newly developed tertiary pyridine-type anion-exchange resin embedded in silica beads. Chromatographic elution experiments were carried out by using a packed column of the new resin and methanol-hydrochloric acid solution as an effluent. We confirmed that the actinides were eluted well from the elution bands of lanthanides. Actinides and lanthanides were eluted according to the reverse order of their atomic number.