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Journal Articles

Measurements of gamma-ray emission probabilities in the decay of americium-244g

Nakamura, Shoji; Terada, Kazushi*; Kimura, Atsushi; Nakao, Taro*; Iwamoto, Osamu; Harada, Hideo; Uehara, Akihiro*; Takamiya, Koichi*; Fujii, Toshiyuki*

Journal of Nuclear Science and Technology, 56(1), p.123 - 129, 2019/01

 Percentile:100(Nuclear Science & Technology)

Accurate data of $$gamma$$-ray emission probabilities are frequently needed when one quantitatively determines the amount of isotope by $$gamma$$-ray measurements or obtains neutron capture cross-sections using them. Americium-243, one of the most important minor actinides, produces $$^{244}$$Am after neutron capture. The 744-keV $$gamma$$-ray decaying from the ground state of $$^{244}$$Am has a relatively large $$gamma$$-ray emission probability c.a. 66%, however, its uncertainty is as large as 29%. The uncertainty of the $$gamma$$-ray emission probability leads to a major factor of the systematic uncertainty on determining an amount of isotope, and therefore the $$gamma$$-ray emission probability was measured by using an activation method and an examined level structure of $$^{244}$$Cm. In this study, the emission probability of 744-keV $$gamma$$ ray was derived as 66.5$$pm$$1.1%, and its uncertainty was improved from 29% to 2%.

Journal Articles

Extraction of trivalent rare earths and minor actinides from nitric acid with ${it N,N,N',N'}$-tetradodecyldiglycolamide (TDdDGA) by using mixer-settler extractors in a hot cell

Ban, Yasutoshi; Suzuki, Hideya; Hotoku, Shinobu; Kawasaki, Tomohiro*; Sagawa, Hiroshi*; Tsutsui, Nao; Matsumura, Tatsuro

Solvent Extraction and Ion Exchange, 37(1), p.27 - 37, 2019/00

A continuous counter-current experiment using TDdDGA was performed using mixer-settler extractors installed in a hot cell. Nitric acid containing minor actinides (MAs: Am and Cm), rare earths (REs: Y, La, Nd, and Eu), and other fission products (Sr, Cs, Zr, Mo, Ru, Rh, and Pd) was fed to the extractor. TDdDGA effectively extracted MAs and REs from the feed, while other fission products were barely extracted. The extracted MAs and REs were back-extracted by bringing them in contact with 0.02 mol/dm$$^{3}$$ nitric acid, and they were collected as the MA-RE fraction. The proportions of MA and RE in the MA-RE fraction were $$>$$ 98% and $$>$$ 86%, respectively. These results demonstrated the applicability of TDdDGA as an extractant for MAs and REs.

Journal Articles

Anion-exchange separation of americium and the lanthanides using a single column

Miyamoto, Yutaka; Yasuda, Kenichiro

Journal of Nuclear and Radiochemical Sciences (Internet), 18, p.13 - 15, 2018/07

A sequential separation technique using an anion-exchange column developed in the previous works have the potential to completely separate picograms of Am from the lanthanides using mixtures of acetic acid, hydrochloric acid, and nitric acid as the eluents, without any functional ligands or special columns. This experimental result implies that ultra-trace actinides, including Am, Pu, U, and Th in environmental samples can be sequentially separated by combination of these mixed-media eluents and an anion exchange column.

Journal Articles

Fabrication and short-term irradiation behaviour of Am-bearing MOX fuels

Kihara, Yoshiyuki; Tanaka, Kosuke; Koyama, Shinichi; Yoshimochi, Hiroshi; Seki, Takayuki; Katsuyama, Kozo

NEA/NSC/R(2017)3, p.341 - 350, 2017/11

In order to investigate the effect of the addition of americium to MOX fuels on the irradiation behaviour, the "Am-1" program is being conducted at the JAEA. The Am-1 program consists of two short-term irradiation tests of 10-min and 24-h irradiation periods, and a steady-state irradiation test. The short-term irradiation tests and their post irradiation examinations (PIEs) have been successfully completed. To date, the data for PIE of the Am-MOX fuels focused on the microstructural evolution and redistribution behaviour of Am at the initial stage of irradiation have been obtained and reported. In this paper, the results obtained from the Am-1 program are reviewed and detailed descriptions of the fabrication and inspection techniques for the Am-MOX fuels prepared for the program are provided. PIE data for the Am-MOX fuels at the initial stage of irradiation have been accumulated. In this paper, unpublished PIE data for the Am-MOX fuels are also presented.

Journal Articles

Self-radiation effects and glassy nature of magnetic transition in AmO$$_2$$ revealed by $$^{17}$$O-NMR

Tokunaga, Yo; Nishi, Tsuyoshi; Nakada, Masami; Ito, Akinori*; Sakai, Hironori; Kambe, Shinsaku; Homma, Yoshiya*; Honda, Fuminori*; Aoki, Dai*; Walstedt, R. E.*

Physical Review B, 89(21), p.214416_1 - 214416_8, 2014/06

 Times Cited Count:6 Percentile:58.6(Materials Science, Multidisciplinary)

The magnetic phase transition near $$T_0=8.5$$ K in AmO$$_2$$ has been investigated microscopically by means of $$^{17}$$O NMR. To avoid complexities arising from sample aging associated with the alpha decay of $$^{243}$$Am, all measurements have been performed within 40 days after sample synthesis. Even during such a short period, however, a rapid change of NMR line shape has been observed at 1.5 K, suggesting that the ground state of AmO$$_2$$ is very sensitive to disorder. We have also confirmed the loss of $$^{17}$$O NMR signal intensity over a wide temperature range below $$T_0$$, and more than half of oxygen nuclei are undetectable at 1.5 K. This behavior reveals the persistence of slow and distributed spin fluctuations down to temperatures well below $$T_0$$. In the paramagnetic state, strong NMR line broadening and spatially inhomogeneous spin fluctuations have been observed. The results are all indicative of short-range, spin-glass-like character for the magnetic transition in this system.

Journal Articles

Separation of minor actinides and lanthanides from nitric acid solution by R-BTP extraction resin

Hoshi, Harutaka*; Wei, Y.*; Kumagai, Mikio*; Asakura, Toshihide; Morita, Yasuji

Recent Advances in Actinide Science, p.596 - 598, 2006/06

Recently, extraction selectivity for trivalent minor actinides (MA = Am and Cm) over lanthanides (Ln) has been found in some extractants containing soft donor, such as S or N, ligands. Kolarik et al. reported that a new N-donor ligand 2,6-bis(5,6-dialkyl-1,2,4-triazine-3-yl)-pyridine (R-BTP) shows high selectivity for MA (III) over Ln(III) [1]. However, protonation of R-BTP results in its acidic hydrolysis in acidic medium. Stability in acidic solution was improved by substitution of long normal chain or branched chain [2]. In this work, separation of MA(III) and Ln(III) from nitric acid solution was studied by using novel R-BTP impregnated resin. Branched R-BTP resin had high affinity for Am from up to 4 M HNO$$_{3}$$ solution and its distribution coefficient was over 10$$^{4}$$.

Journal Articles

Extraction of groundwater humic substances and characterization by synthetic resin

Ueda, Masato; Sakamoto, Yoshiaki*

Genshiryoku Bakkuendo Kenkyu, 12(1-2), p.31 - 39, 2006/03

no abstracts in English

Journal Articles

Separation of trivalent actinides from lanthanides by using R-BTP resins and stability of R-BTP resin

Hoshi, Harutaka*; Wei, Y.*; Kumagai, Mikio*; Asakura, Toshihide; Morita, Yasuji

Journal of Alloys and Compounds, 408-412, p.1274 - 1277, 2006/02

 Times Cited Count:31 Percentile:14.55(Chemistry, Physical)

For the development of advanced aqueous reprocessing system, it is one of the most important subjects to separate minor trivalent actinides (MA = Am and Cm). Recently, extraction selectivity for MA(III) over Ln(III) has been found in some extractants containing soft donor, such as S or N, ligands. Kolarik et al. reported that a new N-donor ligand 2,6-bis(5,6-dialkyl-1,2,4-triazine-3-yl)-pyridine (R-BTP) shows high selectivity for MA (III) over Ln(III). The novel silica-based extraction resins were prepared by impregnating some R-BTP molecules into a macroreticular styrene-divinylbenzene copolymer which is immobilized in porous silica particles with a mean diameter of 50 $$mu$$m. Separation of simulated high level liquid waste solution containing Ln(III) and trace amount of Am(III) was studied. Am(III) was mutually separated from Ln(III) through a packed column with R-BTP impregnating resin, very high decontamination factor ($$>$$ 10$$^{7}$$) for Am, and all the elements were recovered quantitatively.

Journal Articles

Novel separation system of trivalent actinides-combined effects of substituted tris(2-pyridylmethyl)amine ligand and hydrophobic counter-anion

Ishimori, Kenichiro*; Watanabe, Masayuki; Kimura, Takaumi; Yaita, Tsuyoshi; Yamada, Takashi*; Kataoka, Yumiko*; Shinoda, Satoshi*; Tsukube, Hiroshi*

Chemistry Letters, 34(8), p.1112 - 1113, 2005/08

 Times Cited Count:11 Percentile:55.18(Chemistry, Multidisciplinary)

Stereochemical substitution on tripod ligand significantly offered efficient separation of trivalent actinides from trivalent lanthanides. Liquid-liquid extraction using chiral tris(2-pyridylmethyl)amine ligands as an extractant exhibited high efficiency and selectivity for trivalent actinides. A combination of chiral ligand and 2-bromodecanoic acid further enhanced extraction performance for trivalent actinides.

Journal Articles

Status of fuel transmutation programmes in Japan and France; Lessons drawn from results

Arai, Yasuo; Pillon, S.*

Proceedings of International Conference ATALANTE 2004 Advances for Future Nuclear Fuel Cycles (CD-ROM), 9 Pages, 2004/06

no abstracts in English

Journal Articles

$$alpha$$-decays of neutron-deficient americium isotopes

Sakama, Minoru*; Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Haba, Hiromitsu*; Goto, Shinichi*; Shibata, Michihiro*; Kawade, Kiyoshi*; et al.

Physical Review C, 69(1), p.014308_1 - 014308_11, 2004/01

 Times Cited Count:17 Percentile:27.81(Physics, Nuclear)

no abstracts in English

Journal Articles

Migration models of neptunium and americium in groundwater under the present condition of humic substances

Tanaka, Tadao; Sakamoto, Yoshiaki; Sawada, Hiroshi; Ogawa, Hiromichi

JAERI-Conf 2003-010, p.134 - 141, 2003/09

We have performed migration experiments of Np(V) and Am(III) for crushed granite, under the coexistent condition with humic acid substance. As for Np, the periodical concentration changes in the breakthrough curve and the migration velocity of Np passed through the column were not affected by the coexistence of the humic substance. As for Am, on the other hand, the periodical concentration changes in the breakthrough curve were affected by the humic substance concentration. The migration behavior of Am passed through the present column system could be expressed by a migration model taking account of the non-equilibrium state.

JAEA Reports

Re-evaluation of neutron nuclear data for $$^{242m}$$Am, $$^{243}$$Am, $$^{99}$$Tc and $$^{140}$$Ce

Nakagawa, Tsuneo; Iwamoto, Osamu; Hasegawa, Akira

JAERI-Research 2002-035, 94 Pages, 2002/12

JAERI-Research-2002-035.pdf:2.73MB

no abstracts in English

JAEA Reports

The Sorption database of radionuclides for cementitious materials

Kato, Hiroshige*; Mine, Tatsuya*; Mihara, Morihiro; Oi, Takao; Honda, Akira

JNC-TN8400 2001-029, 63 Pages, 2002/01

JNC-TN8400-2001-029.pdf:1.81MB

Cementitious materials will be used for the TRU waste repository as a component of engineered barrier system. The distribution coefficients which represent the retardation of radionuclides migration for the cementitious materials would be one of the important parameter for the safety assessment. The much information of radionuclide sorption onto the cementitious materials has been accumulated through the study in the world. Therefore it is necessary to compile the information and Kd of the radionuclides reported in previous studies. In this report, the Kd of the important radionuclides, such as C, Ni, Se, Sr, Zr, Nb, Mo, Tc, Sn, I, Cs, Sm, Pb, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, for the cementitious materials were compiled as the Sorption Database (SDB). For radionuclides to be sensitive to the redox potential, e.g. Se, Tc, Pa, U, Pu and Np, some Kds measured under the controlled atmosphere had been reported, and few Kds measured under the controlled redox potential had been reported. For Se, Mo, Sm, Cm and Ac, the distribution coefficients had not been reported, therefore distribution coefficients of Se and Mo for OPC (Ordinary Portland Cement) pastes were measured by batch sorption experiments and these data were added into the SDB.

JAEA Reports

Improvement of evaluated neutron nuclear data for $$^{237}$$Np and $$^{241}$$Am

Nakagawa, Tsuneo; Iwamoto, Osamu; Hasegawa, Akira

JAERI-Research 2001-059, 84 Pages, 2002/01

JAERI-Research-2001-059.pdf:4.96MB

no abstracts in English

Journal Articles

Extraction of actinides(III), (IV), (V), (VI) and lanthanides(III) by structurally tailored diamides

Sasaki, Yuji; Tachimori, Shoichi

Solvent Extraction and Ion Exchange, 20(1), p.21 - 34, 2002/01

 Times Cited Count:154 Percentile:4.75(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Behavior of plutonium and americium at liquid cadmium cathode in molten LiCl-KCl electrolyte

Iizuka, Masatoshi*; Uozumi, Koichi*; Inoue, Tadashi*; Iwai, Takashi; Shirai, Osamu; Arai, Yasuo

Journal of Nuclear Materials, 299(1), p.32 - 42, 2001/10

 Times Cited Count:65 Percentile:2.36

no abstracts in English

Journal Articles

Research activities on advanced nuclear fuel cycle in NUCEF

Suzuki, Yasufumi; Dojiri, Shigeru; Ono, Akio; Maeda, Atsushi; Sugikawa, Susumu

Proceedings of International Conference on Back-End of the Fuel Cycle: From Research to Solutions (GLOBAL 2001) (CD-ROM), 7 Pages, 2001/09

no abstracts in English

Journal Articles

Measurements of neutron induced fission cross-section for $$^{242m}$$Am from 0.003eV to 10keV using lead slowing-down spectrometer, thermal neutron facility and time-of-flight method

Kai, Tetsuya; Kobayashi, Katsuhei*; Yamamoto, Shuji*; Cho, H.*; Fujita, Yoshiaki*; Kimura, Itsuro*; Okawachi, Yasushi*; Wakabayashi, Toshio*

Annals of Nuclear Energy, 28(8), p.723 - 739, 2001/05

 Times Cited Count:6 Percentile:51.53

no abstracts in English

Journal Articles

Luminescence study on solvation of americium(III), curium(III) and several lanthanide(III) ions in nonaqueous and binary mixed solvents

Kimura, Takaumi; Nagaishi, Ryuji; Kato, Yoshiharu; Yoshida, Zenko

Radiochimica Acta, 89(3), p.125 - 130, 2001/05

 Times Cited Count:53 Percentile:3.31(Chemistry, Inorganic & Nuclear)

no abstracts in English

118 (Records 1-20 displayed on this page)