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Journal Articles

Study on the relation between the crystal structure and thermal stability of FeUO$$_{4}$$ and CrUO$$_{4}$$

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

https://doi.org/10.1016/j.jnucmat.2022.153847
 Times Cited Count：3 Percentile：68.71(Materials Science, Multidisciplinary)

FeUO$$_{4}$$, CrUO$$_{4}$$, and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO$$_{4}$$ and CrUO$$_{4}$$, their crystal structures were evaluated in detail. A Raman band was observed at 700 cm$$^{-1}$$ in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ was composed of a uranyl-like structure in its lattice regardless of its "x"' value. M$"o$ssbauer measurements indicated that the Fe in FeUO$$_{4}$$ and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ were trivalent. Furthermore, Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ lost its symmetry around Fe$$^{mathrm{III}}$$ with increasing electron densities around Fe$$^{mathrm{III}}$$, as the abundance of Cr increased. These results suggested no significant structural differences between FeUO$$_{4}$$ and CrUO$$_{4}$$. Thermogravimetric measurements for UO$$_{2}$$, FeUO$$_{4}$$, and CrUO$$_{4}$$ showed that the temperature at which FeUO$$_{4}$$ decomposed under an oxidizing condition (approximately 800 $$^{circ}$$C) was significantly lower than the temperature at which the decomposition of CrUO$$_{4}$$ started (approximately 1250 $$^{circ}$$C). Based on these results, we concluded that the decomposition of FeUO$$_{4}$$ was triggered by an "in-crystal" redox reaction, i.e., Fe$$^{mathrm{III}}$$ $${+}$$ U$$^{mathrm{V}}$$ $$rightarrow$$ Fe$$^{mathrm{II}}$$ $${+}$$ U$$^{mathrm{VI}}$$, which would not occur in the CrUO$$_{4}$$ lattice because Cr$$^{mathrm{III}}$$ could never be reduced under the investigated condition. Finally, the existence of Cr$$^{mathrm{III}}$$ in FexCr$$_{1-x}$$UO$$_{4}$$ effectively suppressed the decomposition of the Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ crystal, even at a very low Cr content.

Journal Articles

Study of chemical etching conditions for alpha-particle detection and visualization using solid state nuclear track detectors

Yamada, Ryohei; Odagiri, Taiki*; Iwaoka, Kazuki*; Hosoda, Masahiro*; Tokonami, Shinji*

Radiation Environment and Medicine, 8(1), p.21 - 25, 2019/02

http://crss.hirosaki-u.ac.jp/rem_archive/radiation-environment-and-medicine-vol-8-no-1

We evaluate radon/thoron and its progeny concentration using passive-type monitors using CR-39 plates. After exposure, it is necessary to do chemical etching for CR-39 plates. In the present study, we considered shortening of chemical etching time for CR-39 and enlargement of the track diameter (i.e. etch pit diameter) aiming for introduction of automatic counting system in the future. Optimum conditions were determined by changing solution concentration, solution temperature and etching time. As a result, the optimized conditions (concentration, temperature and etching time) were determined to be 8 M NaOH solution, 75 degrees Celsius and 10 hours. This result of etching time showed that the chemical etching was completed in less than half of conventional etching time. Furthermore, it was suggested that shorter etching time would be possible if we do not consider the enlargement of conventional track diameter.

Journal Articles

Completion of solidification and stabilization for Pu nitrate solution to reduce potential risks at Tokai Reprocessing Plant

Mukai, Yasunobu; Nakamichi, Hideo; Kobayashi, Daisuke; Nishimura, Kazuaki; Fujisaku, Sakae; Tanaka, Hideki; Isomae, Hidemi; Nakamura, Hironobu; Kurita, Tsutomu; Iida, Masayoshi*; et al.

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04

TRP has stored the plutonium in solution state for long-term since the last PCDF operation in 2007 was finished. After the great east Japan earthquake in 2011, JAEA had investigated the risk against potential hazard of these solutions which might lead to make hydrogen explosion and/or boiling of the solution accidents with the release of radioactive materials to the public when blackout. To reduce the risk for storing Pu solution (about 640 kg Pu), JAEA planned to perform the process operation for the solidification and stabilization of the solution by converted into MOX powder at PCDF in 2013. In order to perform PCDF operation without adaption of new safety regulation, JAEA conducted several safety measures such as emergency safety countermeasures, necessary security and safeguards (3S) measures with understanding of NRA. As a result, the PCDF operation had stared on 28th April, 2014, and successfully completed to convert MOX powder on 3rd August, 2016 for about 2 years as planned.

Journal Articles

Effect of solute atoms on dislocation motion in Mg; An electronic structure perspective

Tsuru, Tomohito; Chrzan, D. C.*

Scientific Reports (Internet), 5, p.8793_1 - 8793_8, 2015/03

https://doi.org/10.1038/srep08793
 Times Cited Count：68 Percentile：86.71(Multidisciplinary Sciences)

Much of the world's future economy hedges on the ability to improve the efficiency of mechanical machines without sacrificing their performance. This requires the development of lighter and stronger structural alloys. Magnesium alloys are very promising for structural applications, but they suffer from a fatal flaw. The mobility of the dislocations is determined by the bonding within the alloy, and this bonding is best modeled using approaches rooted firmly in quantum mechanics. Here, we compute the electronic structure of a screw dislocation gliding on a prismatic plane within Mg as it passes over its Peierls barrier. We show that the ductility of Mg is increased because some substitutional additions strongly bind to and stabilize a compact core structure for screw dislocations that are formally able to glide on both the basal and prismatic planes.

Journal Articles

Rapid dissolution techniques with microwave heating devices for solidified products made from non-metallic wastes by plasma melting

Haraga, Tomoko; Kameo, Yutaka; Nakashima, Mikio

Bunseki Kagaku, 55(1), p.51 - 54, 2006/01

https://doi.org/10.2116/bunsekikagaku.55.51
 Times Cited Count：4 Percentile：14.45(Chemistry, Analytical)

A relatively large quantity of sample solutions have to be prepared for radiochemical analysis of solidified products yielded by plasma melting treatment of non-metallic radioactive wastes. In order to dissolve the solidified products sample rapidly, dissolution method with microwave heating devices was applied. In a conventional method only by external heating with various mixtures of acids (HNO$$_{3}$$, HF, HClO$$_{4}$$ and H$$_{2}$$SO$$_{4}$$), a 0.1 g amount of the sample was dissolved with difficulty. However, applying the microwave assisted dissolution method, a 1 g amount of the sample was completely dissolved in a shorter time. Thereby the time for dissolution procedures was shortened less than a one-tenth. The present dissolution method was successfully applied to the blast furnace slag as a reference material to determine main elements with good precision.

Journal Articles

Fabrication and electrochemical behavior of nitride fuel for future applications

Arai, Yasuo; Minato, Kazuo

Journal of Nuclear Materials, 344(1-3), p.180 - 185, 2005/09

https://doi.org/10.1016/j.jnucmat.2005.04.039
 Times Cited Count：24 Percentile：82.03(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Reactivity effect measurement of neutron interaction between two slab cores containing 10% enriched uranyl nitrate solution without neutron isolater

Tonoike, Kotaro; Miyoshi, Yoshinori; Okubo, Kiyoshi

Journal of Nuclear Science and Technology, 40(4), p.238 - 245, 2003/04

https://doi.org/10.3327/jnst.40.238
 Times Cited Count：2 Percentile：19(Nuclear Science & Technology)

The reactivity effect of neutron interaction between two identical units containing low enriched (10% $$^{235}$$ enrichment) uranyl nitrate solution was measured in the STACY. The unit has 350mm of thickness and 690mm of width and distance between those two units was adjustable from 0mm to 1450mm. Condition of the solution was about 290gU/L in uranium concentration, about 0.8N in free nitric acid molarity, 24$$sim$$27$$^{circ}$$C in temperature and about 1.4g/cm$$^{3}$$ in solution density. The reactivity effect was estimated from variation of critical solution level from 495mm to 763mm depending on the core distance. The reactivity effect was also evaluated by the solid angle method and a computational method using the continuous energy Monte Carlo code MCNP-4C and the nuclear data library JENDL3.2. Comparison of those estimations is presented.

Journal Articles

Study on the stability of AmN and (Am,Zr)N

Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Minato, Kazuo; Numata, Masami

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.2285 - 2291, 2003/00

Stability of AmN and (Am,Zr)N was studied comparatively from the viewpoints of the hydrolytic and evaporative behavior. AmN powder reacted with moisture to form hydroxide Am(OH)$$_{3}$$, while the solid solution (Am$$_{0.1}$$Zr$$_{0.9}$$)N remained stable as long as 1000 hours. Stabilization effect of ZrN was found to depend significantly on its mole fraction from the experiments on (Dy,Zr)N. In the oxidation experiments on (Dy,Zr)N by TG-DTA technique, rapid weight gain by the oxidation occurred above 700 K. Effect of ZrN on the stability against oxygen was slight. Nitrogen release by the evaporation of AmN and (Am$$_{0.1}$$Zr$$_{0.9}$$)N in He gas flow was measured by gas chromatography. Evaporation rate constants of AmN were obtained at 1623-1733 K. Although the evaporation rate constant of AmN in the solid solution were lower than those of the pure AmN, the selective evaporation of AmN from the solid slution were recognized, which resulted in a decrease in the Am mole fraction.

Journal Articles

Oxygen solubility in dysprosium mononitride prepared by carbothermic synthesis

Takano, Masahide; Ito, Akinori; Akabori, Mitsuo; Ogawa, Toru

Journal of Alloys and Compounds, 327(1-2), p.235 - 239, 2001/08

https://doi.org/10.1016/S0925-8388(01)01443-8
 Times Cited Count：13 Percentile：60.77(Chemistry, Physical)

no abstracts in English

Journal Articles

Oxygen potential of solid solution Eu$$_{y}$$U$$_{1-y}$$O$$_{2+x}$$

Fujino, Takeo*; Sato, Nobuaki*; Yamada, Kota*; *; Fukuda, Kosaku; Serizawa, Hiroyuki; Shiratori, Tetsuo

Journal of Nuclear Materials, 265(1-2), p.154 - 160, 1999/00

https://doi.org/10.1016/S0022-3115(98)00502-9
 Times Cited Count：6 Percentile：45.57(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Solubility of magnesium in uranium dioxide

Fujino, Takeo*; *; Sato, Nobuaki*; Yamada, Kota*; Fukuda, Kosaku; Serizawa, Hiroyuki; Shiratori, Tetsuo

Journal of Nuclear Materials, 246(2-3), p.150 - 157, 1997/00

https://doi.org/10.1016/S0022-3115(97)00143-8
 Times Cited Count：22 Percentile：83.3(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Study on the development of the lattice strain in (Mg,U)O$$_{2+x}$$ solid solution

Serizawa, Hiroyuki; Shiratori, Tetsuo; Fukuda, Kosaku; Fujino, Takeo*; Sato, Nobuaki*

Journal of Alloys and Compounds, 218, p.149 - 156, 1995/00

https://doi.org/10.1016/0925-8388(94)01385-3
 Times Cited Count：3 Percentile：37.09(Chemistry, Physical)

no abstracts in English

Journal Articles

Lattice stability and structure of $$delta$$-UZr$$_{2}$$ at elevated temperatures

Akabori, Mitsuo; Ogawa, Toru; Ito, Akinori; Morii, Yukio

Journal of Physics; Condensed Matter, 7, p.8249 - 8257, 1995/00

https://doi.org/10.1088/0953-8984/7/43/005
 Times Cited Count：46 Percentile：89.28(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Rise time spectra of $$alpha$$ and $$beta$$($$gamma$$) rays from solid and solution sources with several solid scintillators

Usuda, Shigekazu; Mihara, Akira; Abe, Hitoshi

Nuclear Instruments and Methods in Physics Research A, 321, p.247 - 253, 1992/00

https://doi.org/10.1016/0168-9002(92)90396-L
 Times Cited Count：21 Percentile：84.73(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Lattice parameter of UN-PuN solid solution

; Arai, Yasuo; Iwai, Takashi; Omichi, Toshihiko

Journal of Nuclear Science and Technology, 28(7), p.689 - 691, 1991/07

https://doi.org/10.3327/jnst.28.689

no abstracts in English

Journal Articles

Thermodynamic properties of Th$$_{0}$$$$_{.}$$$$_{8}$$$$_{0}$$U$$_{0}$$$$_{.}$$$$_{2}$$$$_{0}$$O$$_{2}$$$$_{+}$$$$_{x}$$ solid solution

Ugajin, Mitsuhiro; ; Shiba, Koreyuki

Journal of Nuclear Materials, 116(2-3), p.172 - 177, 1983/00

https://doi.org/10.1016/0022-3115(83)90099-5
 Times Cited Count：15 Percentile：81.67(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Oxygen potentials of(Th,U)O$$_{2}$$$$_{+}$$$$_{x}$$ solid solutions

Ugajin, Mitsuhiro

Journal of Nuclear Materials, 110, p.140 - 146, 1982/00

https://doi.org/10.1016/0022-3115(82)90138-6
 Times Cited Count：24 Percentile：88.76(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Stoichiometry of fully oxidized PuO$$_{2}$$-NdO$$_{1}$$$$_{.}$$$$_{5}$$ and PuO$$_{2}$$-YO$$_{1}$$$$_{.}$$$$_{5}$$ solid solutions

; ; ;

Journal of Nuclear Science and Technology, 19(8), p.681 - 683, 1982/00

https://doi.org/10.3327/jnst.19.681
 Times Cited Count：2 Percentile：43.95(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Dissolution and solidification of aluminum capsule in production of Mo-99 by sublimation from neutron-irradiatedUO$$_{2}$$

; ; ; *

Journal of Nuclear Science and Technology, 17(1), p.83 - 85, 1980/00

https://doi.org/10.3327/jnst.17.83
 Times Cited Count：0 Percentile：0.29(Nuclear Science & Technology)

no abstracts in English

Journal Articles

The Anomalies in Temperature Dependence of the Yield Stress of Cu Base Solid Solutions

; *

Journal of the Physical Society of Japan, 31(4), p.1056 - 1068, 1971/10

https://doi.org/10.1143/JPSJ.31.1056
 Times Cited Count：81

no abstracts in English

25 (Records 1-20 displayed on this page)