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Abstract  

The oxidation states of antimony and tellurium fission products formed in the aqueous solutions of233U and235U irradiated in a reactor were studied by means of anion exchange method. Results were corrected for the thermal reactions such as radiation induced reactions using double tracers for each element. In hot reactions, the isotopes formed independently by fission take their reduced states almost completely, whereas the isotopes formed by β-decay of their precursors favor their oxidized states. The fractions of the tellurium isotopes in the oxidized state depend on the β-decay energy of their precursors, whereas those of the antimony isotopes are nearly constant irrespective of the β-decay energy. The different behaviors between those two elements would reflect the chemical properties of their precursors.

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Abstract  

Extraction behaviors of Pd(II) in the TRUEX and PUREX solvent extractions were studied by using octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide. The effect of scrubbing in the TRUEX solvent extraction was demonstrated by adding oxalic acid. The distribution ratios of palladium (D Pd's) in the diluted region of [HNO3] were found to depend strongly on the fraction of cationic species, Pd(NO3)+, existed in the aqueous phase. The gradual decrease of DPd with the increase of acidity beyond [H+] 1 mol·dm-3 was controlled by the formation of the anionic species Pd(NO3)3 -.

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Abstract  

Sorption behavior of Am(III) onto granite was investigated. The distribution coefficient (K d ) of Am(III) onto granite was determined in the solution of which pH was ranged from 2.9 to 11.4 and ionic strength was set at 10−2 and 10−1. TheK d values were found to increase with increasing pH and with decreasing ionic strength. The obtained data were successfully analyzed by applying an electrical double layer model. The optimum parameter values of the double layer electrostatics and adsorption reactions were obtained, and the selective adsorption behavior of Am(III) onto the granite was discussed.

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Abstract  

Adsorption behavior of fission products in nitric acid solution on various alloys and metals was studied by using a multitracer produced by neutron irradiation of UO2. The adsorption behavior of the fission products 99Mo, 131I, 132Te, 140La, and 143Ce, and 239Np was simultaneously studied. Some chemical decontamination tests were also examined. Clear adsorption of 99Mo, 131I, and 132Te was observed, whereas adsorption of 140La, 143Ce, and 239Np was not. The adsorption characteristics were discussed by considering anion-exchange reaction and surface complexation.

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Abstract  

In order to improve the accuracy of reactor neutron activation analysis, flux gradients and spectrum changes in the irradiation capsule have been studied at the Kyoto University Reactor (KUR). The flux and spectrum monitoring samples of Fe, Co, Au, Sb, U and Ni were placed at several positions in a polyethylene irradiation capsule of 24 mm inner diameter and 98 mm length, and were irradiated in a pneumatic irradiation facility (Pn-2). The flux gradients were found to be rather negligible in the vertical (axial) direction while they were considerable in the radial one. The flux gradient was around 5%/cm for thermal neutrons and 10%/cm for epithermal and fast neutrons. The spectrum changes were dependent on the materials (polyethylene and silica) filled in the capsule. Based on these observations, the effect of the flux gradients and spectrum changes on the accuracy of reactor neutron activation analysis was discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Kubo
,
H. Moriyama
,
Y. Tsuruoka
,
S. Sakamoto
,
E. Koseto
,
T. Saito
, and
K. Nishiyama

Abstract  

An elemental analysis method using muonic X-rays has been developed. Applying the unique features of the negative muon, this method enables elemental distribution in an object to be obtained three dimensionally and non-destructively. Especially, by choosing the incident muon beam energy, depth-profiling as deep as several cm from the surface can be achieved by detecting the high energy muonic X-rays carrying the information of the atom which captured the muon. We obtained some preliminary results and showed the applicability of the technique in future analytical facilities.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
S. Akahori
,
E. Tega
,
Y. Morimoto
,
K. Okuno
,
M. Nishikawa
,
K. Munkata
,
H. Moriyama
,
K. Kawamoto
, and
M. Okada

Abstract  

The effects of irradiation damages induced by neutron irradiation on tritium release processes were studied in Li4SiO4. It was shown that the thermal annealing process of the damages consisted of two processes of a fast and a slow process. The activation energies were determined to be 0.21 eV and 1.1 eV, respectively. From the experimental results, it was suggested that the migration of tritium and displaced oxygen into the damages plays an important role in both thermal annealing processes.

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