Chemical analysis of americium samples irradiated under fast neutron spectra

Koyama, Shinichi; Mitsugashira, Toshiaki*

Journal of Nuclear Science and Technology, 45(Suppl.6), p.55 - 64, 2008/09

https://doi.org/10.1080/00223131.2008.10875977

In order to evaluate the transmutation behavior of americium under fast neutron spectra, two irradiated Am samples (No.69, No.70) were analyzed by radiochemical methods. These samples were irradiated in the experimental fast reactor JOYO for 275 effective full power day by the fast neutron flux. Am, Am, Pu to Pu and Cm to Cm were clearly observed. The isotopic composition of Am exceeded 1.01 at% for sample No.69 and 1.48 at% for No.70. It was suggested that this difference came from the different rates of neutron capture reaction.

Recent status of radiochemical analysis of irradiated trans-uranium targets

Koyama, Shinichi; Osaka, Masahiko; Mitsugashira, Toshiaki

Czechoslovak Journal of Physics, 56(Suppl.D), p.D571 - D578, 2006/12

We have developed a sequential radiochemical separation method (SRCS) in order to isolate each trans-uranium element (TRU) contained in a TRU target (or fuel) irradiated in the experimental fast reactor JOYO. The chemical separation procedures for SRCS consist of the following steps. (1) Target dissolution with a 8M of HNO solution including hydrogen peroxides as a valence control reagents for Pu and Np to their tetravalent states. (2) Sequential elution of main fission products (FPs) including trivalent actinides (An(III)) and lanthanides (Ln(III)) by washing the anion exchange resin column with 8M HNO. (3) Elution of U(VI) from the same column with 8M HNO and the change the effluent to 11.6M HCl. (4) Elution of Pu(III) from the same column by reducing Pu(IV) to Pu(III) with 11.6M HCl-0.1M NHI solution. (5) Group separation for Ln(III) and An(III) by using tertiary pyridine-type anion exchange resin embedded in silica bead. (6) Mutual separation of Am(III) and Cm(III), also for each lanthanide, by anion exchange resin. For the step 5 and 6, the effluent used was 3/7(v/v) mixture of methanol and HCl and 9/1(v/v) mixture of methanol and 0.013M HNO, respectively. The decontamination factor of Pu for the isolated Np was much higher than 10. The isotopic composition of isolated trans-uranium was determined mainly by thermal ionization mass spectroscopy. The SRCS sheet was applied to the analyses of MOX fuels irradiated in the experimental fast reactor JOYO. On the basis of isotope analysis, the transmutation and incineration behavior (T-I behavior) of trans-uranium nuclides were elucidated.

An experimental investigation of accumulation and transmutation behavior of americium in the MOX fuel irradiated in a fast reactor

Osaka, Masahiko; Koyama, Shinichi; Maeda, Shigetaka; Mitsugashira, Toshiaki*

Annals of Nuclear Energy, 32(7), p.635 - 650, 2005/05

https://doi.org/10.1016/j.anucene.2004.12.009

Americium isotopes generated in the MOX fuel irradiated in the experimental fast reactor JOYO were analyzed by applying a sophisticated radiochemical technique. Americium was isolated from the irradiated MOX fuel by a combination method of anion-exchange chromatography and oxidation of Am. The isotopic ratio of americium and its content were determined by thermal ionization mass spectroscopy and alpha-spectrometry, respectively. The americium isotopic ratio was similar for all the specimens, but was significantly different from that of PWR-MOX. On the basis of present analytical results, the accumulation and transmutation behavior of americium nuclides in a fast reactor was discussed from viewpoints of neutron spectrum dependence and the isomeric ratio of Am capture reaction Am for the capture reaction. The estimated isomeric ratio was about 87 %, which was close to recently evaluated value. A rapid estimation method of Am content by using Pu to Pu index was adopted and was proved to be valid for the spent fuel irradiated in the fast reactor.

Analysis of Curium in MOX Fuel Irradiated in Fast Reactor

Osaka, Masahiko; Osaka, Masahiko; Koyama, Shinichi; Mitsugashira, Toshiaki

Global 2003; International Conference on Atoms for Prosperity: Upda, 0 Pages, 2003/00

Cm isotopes formed in irradiated MOX fuel in the experimental fast reactor JOYO were analyzed by applying a sophisticated radiochemical technique. Cm was isolated from the irradiated fuel by anion ion-exchange chromatography using a mixed medium of nitric acid and methanol. The isotopic ratio of Cm and its content were determined by thermal ionization mass spectroscopy and alpha-spectrometry, respectively. U, Pu, Am and Nd were also isolated and analyzed for the determination of the Cm content and burnup. The Cm content was less than 0.004 at.%, which is much smaller than that of PWR-MOX at 60 GWd/t. On the basis of the present analytical results, the transmutation behavior of Cm isotopes in a fast reactor was discussed from various viewpoints. Transmutation speeds of Cm isotopes were estimated; the speed for 246Cm, which is known to be a key nuclide in the transmutation of Cm, was smaller than the previously reported value. Transmutation behavior of each Cm isotope was also eval

Analysis of curium isotopes in mixed oxide fuel irradiated in fast reactor

Osaka, Masahiko; Koyama, Shinichi; Morozumi, Katsufumi; Namekawa, Takushi; Mitsugashira, Toshiaki

Journal of Nuclear Science and Technology, 38(10), p.912 - 914, 2001/10

https://doi.org/10.3327/jnst.38.912

None

Analysis of Cm contained in irradiated fuel of experimental fast reactor "JOYO"; Development of the analytical technique and measurement of Cm

Osaka, Masahiko; Koyama, Shinichi; Mitsugashira, Toshiaki; Morozumi, Katsufumi; Namekawa, Takashi

JNC TN9400 2000-058, 49 Pages, 2000/04

JNC-TN9400-2000-058.pdf:1.22MB

The analytical technique for Cm contained in a MOX FUEL was developed and analysis of Cm contained in irradiated fuel of experimental fast reactor "JOYO" was carried out, to contribute to evaluation of transmutation characteristics of MA nuclide in the fast reactor. The procedure of ion-exchange separation of Cm with nitric acid-methanol mixed media essential for the isotopic analysis in irradiated MOX fuel was adopted considering for being rapid and easy. The fundamental test to grasp separation characteristics of this procedure, such as Cm elution position and separation capacity between Cm and Am or Eu, was carried out. ln applying this procedure to the analysis of Cm contained in actual specimen, separation condition was evaluated and optimized, and the procedure consist of impurity removal and Am removal process was devised. This procedure resulted in high recovery rate of Cm and high removal rate of Am and impurity which becomes a problem in sample handling and mass-spectrometry such as Eu and Cs. The Cm separation test from irradiated MOX fuel was carried out using this technique, and Cm isotopic ratio analysis was enabled. The analytical technique for Cm contained in irradiated MOX fuel was established using the procedure of ion-exchange separation with nitric acid-methanol mixed media. The analysis of Cm contained in irradiated MOX fuel of experimental fast reactor "Joyo" was carried out. As a result, it was revealed from measured data that Cm content rate was 1.4 4.0lO atom%, small amount of Cm was generated and Cm isotopic ratio was constant above burn-up 60GWd/t.

Analysis of Minor Actinides in Mixed Oxide Fuel Irradiated in Fast Reactor, 1; Determination of Neptunium-237

Koyama, Shinichi; ; ; Mitsugashira, Toshiaki; Morozumi, Katsufumi;

Journal of Nuclear Science and Technology, 35(6), 406 Pages, 1998/00

https://doi.org/10.3327/jnst.35.406

None

None

Koyama, Shinichi; ; Osaka, Masahiko; ; ; Mitsugashira, Toshiaki

Proceedings of International Conference on Future Nuclear Systems (Global'97), Vol.2, 0 Pages, 1997/10

no abstracts in English

Study on Am and Cm analysis in irradiated fuels, 1; The result of mutual separation Am and Cm

Osaka, Masahiko; Koyama, Shinichi; Otsuka, Yuko; Mitsugashira, Toshiaki; Konno, Koichi; Kajitani, Mikio

PNC TN9410 96-297, 79 Pages, 1996/11

PNC-TN9410-96-297.pdf:2.87MB

As a part of evaluation of irradiation behavior and burnup characteristics of MA nuclides such as Np, Am and Cm in MA containing MOX fuel, we are studying the quantitative analysis techniques for MA nuclides in irradiated fuel. In this study, we studied the mutual separation method for Am and Cm to establish the analysis method for Am and Cm following Np analysis by alpha spectrometry. The measurements of Am and Cm are difficult to analyze quantitatively because the amounts of some nuclides are too small and the number of nuclides are large, whose energies of the alpha radioactive rays are almost same. Therefore we selected to analyze the trace amount of Am and Cm isotopes using mass spectrometry, and have studied the techniques for mutual separation of Am and Cm using oxidation method of Am by NaBiO for standard samples. We have also evaluated the availability of this method for irradiated fuel. Results are as follows. (1)Through the mutual separation tests, we have found the most suitable conditions for separation of both Am and Cm from each other element. The method obtaining Am which contains no Cm is used water for precipitation washing solution, containing Cm is achicved that the remaining ratio of Am (ratio of radioactivity of Am/Cm against before separation) were reduced less than 1/10 for Cm. (2)Applying of this method to irradiated fuel, the coordinate remaining ratio and the chemical yield of Am and Cm were almost same as them in the separation tests. This method to apply various irradiated MOX Fuel is therefore possible. (3)The isotope ratio Am, Am and Am measured by mass spectrometry, which could not be analyzed by radioactive ray spectrometry causing less than detection limit, were 98.55% : 0.62% : 0.83%. We also measured zero of the mass number of 240 and 244 on the specimens and then certified no contamination of Cm to Am.

Solvent extraction of heavy actinides (III) with HDEHP

Takayama, Reona*; Oe, Kazuhiro*; Komori, Yukiko*; Fujisawa, Hiroyuki*; Kuriyama, Ai*; Kikutani, Yuki*; Kikunaga, Hidetoshi*; Kasamatsu, Yoshitaka*; Yoshimura, Takashi*; Takahashi, Naruto*; et al.

no journal, , 

The extraction behavior of trivalent actinides (Am, Cm, Cf, Es, and Fm) into di(2-ethylhexyl)phosphoric acid, HDEHP, in benzene from HNO was studied together with lanthanides. The extraction constants, values, of lanthanides, Am, Cm, Cf, and Es were determined by a batch method using stable lanthanide isotopes and radiotracers of Am, Cm, Cf, and Es, respectively, while that of Fm was measured with Fm which was produced in the U(O,4n) reaction and was on-line supplied by a gas-jet method at the AVF cyclotron of RCNP, Osaka University. The values were determined by the slope analysis for the variation of the distribution ratio as a function of the concentration of HDEHP. We found that the of Fm is smaller than that of Dy in spite of the similar ionic radii while those of other actinides are almost the same as those of each lanthanide with a similar ionic radius.