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Journal Articles

Radiation measurement for safeguards environmental samples by imaging plate

Yasuda, Kenichiro; Sakurai, Satoshi; Gunji, Hideho; Usuda, Shigekazu

Journal of Nuclear Science and Technology, 39(Suppl.3), p.552 - 555, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875528

In order to contribute to the strengthened safeguards system based on the Program 93+2 of the IAEA, Japan Atomic Energy Research Institute (JAERI) constructed the CLEAR facility (Clean Laboratory for Environmental Analysis and Research) and is developing analytical technology for ultra trace amounts of nuclear materials in environmental samples. To avoid cross-contamination among the samples and contamination of the clean rooms, radioactive materials in the samples to be introduced into the CLEAR facility will be limited to a certain amount. For this purpose the authors have examined the feasibility of Imaging-plate method, which is a kind of autoradiography and is suitable for determination on distribution of low-level radioactivity in the samples. Preliminary examination with -ray (K-40), the linearity was obtained in the range of 0.01 - 0.2 Bq. The experiments with -ray (Sm-147) suggested the detection limit of 0.01 Bq, which was equivalent to 2 g of natural uranium. At the presentation, the results on actual environmental samples will be reported.

Journal Articles

Low-energy - and X-ray measurements by means of Compton suppression technique for safeguards environmental samples

Yasuda, Kenichiro; Mori, Masahito*; Miyamoto, Yutaka; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu

Journal of Nuclear Science and Technology, 39(Suppl.3), p.576 - 578, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875534

no abstracts in English

Journal Articles

Sorption characteristics of actinium and protactinium onto soils

Sakamoto, Yoshiaki; Ishii, Tomoaki*; Inagawa, Satoshi*; Gunji, Yasuyoshi*; Takebe, Shinichi; Ogawa, Hiromichi; Sasaki, Tomozo*

Journal of Nuclear Science and Technology, 39(Suppl.3), p.481 - 484, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875511

Sorption behavior of 227Ac and 233Pa onto several kinds of soils has been studied with a sequential extraction technique, for safety assessment of shallow land disposal of uranium bearing waste. After a batch sorption experiment, the sorbed form of 227Ac and 233Pa onto the soils was fractionated into ion exchange form (extraction by KCl+CaCl2), association with Fe+Mn oxides (extraction by NH2OH-HCl and oxalic acid), association with organic materials (extraction by H2O2) and fixation into soil (residual). From the results of the sequential extraction, major part of 227Ac sorbed onto the soils was found in the fraction of the ion exchange form and the fixation into the soils. On the other hand, major part of 233Pa was found in the fraction of the association with Fe+Mn oxides and the fixation into the soils. These results suggest that the sorption behavior of 227Ac and 233Pa is related to the irreversible sorption reaction onto the soils.

Journal Articles

The Development of flow injection technique for rapid uranium determination in urine samples

Kuwabara, Jun; Tolmachyov, S.; Noguchi, Hiroshi

Journal of Nuclear Science and Technology, 39(Suppl.3), p.556 - 559, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875529

no abstracts in English

Journal Articles

Empirical evaluation of the thermodynamic and magnetic properties from the atomic distances of NaCl-type actinide compounds

Omichi, Toshihiko*; Arai, Yasuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.156 - 159, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875432

no abstracts in English

Journal Articles

Heat capacity of neptunium mononitride

Nakajima, Kunihisa; Arai, Yasuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.620 - 623, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875544

no abstracts in English

Journal Articles

Recovery of U by electrolysis of UN in LiCl-KCl eutectic melts

Shirai, Osamu; Uozumi, Koichi*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.745 - 748, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875574

no abstracts in English

Journal Articles

Phase relations between a fluorite and a pyrochlore structure in the system of actinides and zirconium oxides

Yamashita, Toshiyuki; Kuramoto, Kenichi; Nakada, Masami; Yamazaki, Satoshi*; Sato, Tsuyoshi*; Matsui, Tsuneo*

Journal of Nuclear Science and Technology, 39(Suppl.3), p.585 - 591, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875536

no abstracts in English

Journal Articles

Sorption behavior of plutonium(IV) onto soils in the presence of humic acid

Tanaka, Tadao; Nagao, Seiya; Sakamoto, Yoshiaki; Ogawa, Hiromichi

Journal of Nuclear Science and Technology, 39(Suppl.3), p.524 - 527, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875522

Influence of humic acid on the sorption of Pu onto a coastal sand, which does not sorb humic acid, and an ando soil, which sorbs humic acid very well, was examined with respect to molecular sizes of humic acid. Sorption affinity of Pu for the coastal sand decreased with increasing humic acid concentration. As to the ando soil, the sorption affinity of Pu in the presence of humic acid was larger than that in the absence of humic acid, in low humic acid concentration range. These results suggest that apparent sorption affinity of Pu on the soils is dependent on the complexation ability with humic acid and the sorption affinity of the resulting humic complexes. Concentration profiles of Pu in each size fraction of solution before and after the sorption experiment were obtained by ultrafiltration technique. It was found that the complexation and sorption properties of humic acid are dependent on its molecular size and the important molecular size relating to the complexation and sorption properties tends to shift into smaller size ranges with increasing humic acid concentration.

Journal Articles

Uranium(VI) speciation at elevated temperatures and pressures by time-resolved laser-induced fluorescence spectroscopy

Kimura, Takaumi; Nagaishi, Ryuji; Ozaki, Takuo; Arisaka, Makoto*; Yoshida, Zenko

Journal of Nuclear Science and Technology, 39(Suppl.3), p.233 - 239, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875452

no abstracts in English

Journal Articles

Effect of neptunium ions on corrosion of stainless steel in nitric acid solution

Motooka, Takafumi; Kiuchi, Kiyoshi

Journal of Nuclear Science and Technology, 39(Suppl.3), p.367 - 370, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875485

A corrosion of a stainless steel in nitric acid solution containing Np has been studied. Using SUS304L stainless steel, corrosion tests in boiling neptunium nitrate solution were conducted under immersion and heat-transfer condition. By the weight loss measurement of stainless steel and the quantitative analysis of metallic ions dissolved in solution, the corrosion rates were obtained. The surface morphology was observed by scanning electron microscopy. The acceleration mechanism was investigated by electrochemistry and spectrophotometry. The corrosion rate was accelerated by addition of neptunium in nitric acid. Preferential intergranular corrosion was observed. The corrosion was enhanced under heat-transfer condition compared to immersion condition. In polarization measurements, the cathodic over-voltage was decreased; the cathodic current was increased by addition of Np. Spectrophotometric measurements showed that Np(V) oxidized to Np(VI) in boiling nitric acid. The corrosion acceleration mechanism in nitric acid solution containing Np suggested the re-oxidation of Np(V).

Journal Articles

Dissolution of uranium nitrides in LiCl-KCl eutectic melt

Hayashi, Hirokazu; Kobayashi, Fumiaki; Ogawa, Toru; Minato, Kazuo

Journal of Nuclear Science and Technology, 39(Suppl.3), p.624 - 627, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875545

The behavior of the dissolution of uranium nitrides, which is a component of the MA-U mixed nitride fuel, has been investigated. A mixture of uranium nitride, LiCl-KCl and CdCl was contained in a double walled quartz reaction vessel. During the heating, the carrier gas helium was introduced to a gas chromatography apparatus equipped with an automatic gas sampler. A fraction of the gas was sampled and analyzed by a mass analyzer. Most of nitrogen is recovered as N gas from uranium nitrides dissolving in the LiCl-KCl eutectic melt reacted with CdCl above 550 C, which is higher than that for lanthanide nitrides.

Journal Articles

X-ray absorption study of molten uranium chloride system

Okamoto, Yoshihiro; Akabori, Mitsuo; Ito, Akinori; Ogawa, Toru

Journal of Nuclear Science and Technology, 39(Suppl.3), p.638 - 641, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875549

We report local structural features of molten UCl with LiCl-KCl eutectic probed by the U L-edge XAFS(X-ray absorption fine structure). The XAFS measurements were performed in a transmission mode at the BL27B station of the Photon Factory(High Energy Accelerator Organization, Tsukuba, JAPAN). Sample prepared by chlorination of uranium hydride and then reduction with zinc powder was sealed in a quartz cell under reduced pressure. The nearest U $^{3+}$ -Cl distance and the coordination number of Cl around U $^{3+}$ ion were obtained by a curve fitting of the 1st shell XAFS function k(k). The pair potential in the U $^{3+}$ -Cl correlation was evaluated from XAFS simulation by combinational use of the MD and the FEFF8. In addition, valence state of uranium in the melt was evaluated by XANES(X-ray absorption near edge structure) spectra.

Journal Articles

Oxygen potential measurements of pyrochlore-type Zr $_{2}$ M $_{2}$ O $_{7+x}$ 7(M=Pu, Ce) by EMF method

Otobe, Haruyoshi; Nakamura, Akio; Yamashita, Toshiyuki; Ogawa, Toru

Journal of Nuclear Science and Technology, 39(Suppl.3), p.652 - 655, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875553

Pyrochlore-type (P-type) zirconia has been widely studied as a disposable form of the high-level radioactive nuclear waste. We have developed the EMF (electromotive force) measurement system using the cubic zirconia sensor, in order to investigate the oxygen potential (g(O $_{2}$ )) of P-type Zr $_{2}$ Pu(Ce) $_{2}$ O $_{7+x}$ . For P-type Zr $_{2}$ Ce $_{2}$ O $_{7+x}$ at 1078 K, we have found that g(O $_{2}$ ) vs. oxygen composition (x) relationship has different behavior between x more than 0.34 and x less than 0.34. This may suggest that the degree and way of the ordering of oxide ions (O $^{2-}$ ) and oxygen vacancies (V0) should change around x =0.34. We have also measured the g(O $_{2}$ ) vs. temperature (T) relationship between 763 and 1078 K at various x, and derived the partial molar enthalpy (h(O $_{2}$ )) and entropy (s(O $_{2}$ )) of oxygen. It was found that h(O $_{2}$ ) and s(O $_{2}$ ) of P-type Zr $_{2}$ Ce $_{2}$ O $_{7+x}$ exhibit significantly different behavior from those of fluorite-type CeO $_{2-x}$ . The similar experiments are in progress for P-type Zr $_{2}$ Pu $_{2}$ O $_{7+x}$ , and the results are discussed in comparison with those of P-type Zr $_{2}$ Ce $_{2}$ O $_{7+x}$ mentioned above.

Journal Articles

Density measurement of molten NdCl-NaCl and NdCl-KCl system by ray attenuation

Sato, Tadashi; Okamoto, Yoshihiro; Ogawa, Toru

Journal of Nuclear Science and Technology, 39(Suppl.3), p.635 - 637, 2002/11

http://www.tandfonline.com/doi/abs/10.1080/00223131.2002.10875548

Densities of molten chlorides mixtures of NdCl-NaCl and NdCl-KCl systems have been measured using -ray attenuation method as a function of temperature. Gamma ray spectra of Ho-166m radiation source were taken before and after passing through the molten chlorides in a quartz cell by a Ge-detector coupled with muluti-channel analyzer. The density was calculated with observed attenuation factor, cross section data of photons for relevant elements and length of the cell. The measured densities of molten NdCl-NaCl and NdCl-KCl were compared with literature data by dilatometric method.

Journal Articles