Assessment report on research and development activities in FY2020 activity and in prospective evaluation of third mid-to long-term plan "Research and development on high temperature gas-cooled reactor and related heat application technology"

Shinohara, Masanori; Sumita, Junya; Shibata, Taiju; Hirata, Masaru

JAEA-Evaluation 2022-001, 104 Pages, 2022/06

JAEA-Evaluation-2022-001.pdf:28.15MB

Japan Atomic Energy Agency received the annual evaluation of FY2020, the research plan of FY2021 and the prospective evaluation of the third mid- to long-term plan (from FY2015 to FY2021) from the "Evaluation Committee of Research Activities for High Temperature Gas-cooled Reactor (hereinafter referred to as "HTGR") and Related Hydrogen Production Technology" (hereinafter referred to as "Evaluation Committee") which consists of specialists in the fields of evaluation subjects of HTGR and related heat application technology. As a result, for the annual evaluation of FY2020, one of the ten technical committee members concluded a score of "S", eight members concluded "A" and one member concluded "B". The comprehensive evaluation was concluded a score of "A". On the other hand, two humanities and social sciences committee members concluded "B". For the prospective evaluation of the third mid- to long-term plan, one of the ten technical committee members concluded a score of "S", eight members concluded "A" and one member concluded "B". The comprehensive evaluation was concluded a score of "A". On the other hand, two humanities and social sciences committee members concluded "B". This report describes the members of the Evaluation Committee, assessment items, assessment results and JAEA's measures following the assessment.

Developing the soil moisture sensor using optical fiber technique (Joint research)

Komatsu, Mitsuru*; Nishigaki, Makoto*; Seno, Shoji*; Hirata, Yoichi*; Takenobu, Kazuyoshi*; Tagishi, Hirotaka*; Kunimaru, Takanori; Maekawa, Keisuke; Yamamoto, Yoichi; Toida, Masaru*; et al.

JAEA-Research 2012-001, 77 Pages, 2012/09

JAEA-Research-2012-001.pdf:4.85MB

This research focused on methods of estimating the amounts of groundwater recharge, which are normally required as upper boundary conditions in groundwater flow analyses, based on measurements of infiltrating water in the ground, to systematize the methods and establish systems which are stable and measurable on site over a long time. Regarding developing measurement systems, fiber-optic strain measurement methods that enable multiple-point and long-distance measurement were used for measuring three quantities: suction pressure, soil moisture and volumetric water content rate obtained by applying water absorption swelling material, and each measurement was discussed. The results showed that the fiber-optic soil aquameter has two types of practical application: one for measuring suction pressure (Type I), and the other for measuring volumetric water content rate obtained by applying water absorption swelling material (Type III). Furthermore, by using measurement instruments in actual fields, the validity of the two methods for estimating the rainfall infiltration capacities of shallow-layer soils, that is, estimating the capacities either directly by measurements of soil water or from unsaturated hydraulic conductivities, was confirmed.

Core-hole effect on XANES and electronic structure of minor actinide dioxides with fluorite structure

Suzuki, Chikashi; Nishi, Tsuyoshi; Nakada, Masami; Akabori, Mitsuo; Hirata, Masaru; Kaji, Yoshiyuki

Journal of Physics and Chemistry of Solids, 73(2), p.209 - 216, 2012/02

https://doi.org/10.1016/j.jpcs.2011.10.043

The authors investigated theoretically core-hole effects on X-ray absorption near-edge structures (XANES) of Np and Am L in neptunium dioxide (NpO) and americium dioxide (AmO) with CaF-type crystal lattices using the all-electron full-potential linearized augmented plane-wave (FP-LAPW) method. The peak creation mechanism of XANES was shown by examining the electronic structures of these oxides, which indicated that core-hole screening was more marked for AmO than for NpO because of the difference in the charge transfer between these oxides. Furthermore, the results of charge density analysis suggested that the white line was assigned to the quasi-bound state composed of the localized Np d or Am d components and O components, and that the tail structure was created as a result of delocalized standing waves between the Np or Am atoms.

Production and properties of transuranium elements

Nagame, Yuichiro; Hirata, Masaru

Radiochimica Acta, 99(7-8), p.377 - 393, 2011/08

https://doi.org/10.1524/ract.2011.1853

Relativistic density-functional study of solid solubitilty of tansiton metal/-uranium alloys; The Roll of d-d orbital interactions

Kurihara, Masayoshi*; Onoe, Jun*; Hirata, Masaru; Suzuki, Chikashi

Journal of Alloys and Compounds, 509(4), p.1152 - 1156, 2011/01

https://doi.org/10.1016/j.jallcom.2010.08.153

The alloying behavior of transition metals (TMs) in solid -phase uranium (-U), which is expected to be used as fuel for next-generation nuclear reactors, is investigated using the discrete-variational Dirac-Fock-Slater molecular orbital method. Using a model cluster, U/TM, as the minimum unit of -U/TM alloys, we evaluate the d-orbital energy of the TM (Md), the bond order between the TM and U atoms, and the orbital overlap population (OOP) between the atomic orbitals of the TM and U atoms. We subsequently examine the effect of these quantities on the maximum solid solubility (MSS) of the -U/TM alloys. Md and the OOP (U 6d-TM d) exhibit good correlations with the MSS for -U/TM alloys, so that the interaction between the U-6d and TM-d atomic orbitals is found to play a key role in determining the MSS of the -U/TM alloys. The magnitude of the MSS can be explained in terms of the stabilization energy caused by U 6d-TM d orbital interactions for -U/TM alloys, which is affected by the Md and the OOP. The exponential dependence of the MSS on Md and the OOP is explained in terms of the equilibrium constant obtained using a substitution cluster model for -U/TM alloys. We also map the MSS of -U/TM alloys using the Md and the OOP as the alloying parameters. These results will assist the quantum design of nuclear fuel materials for other alloy systems besides the present alloy system.

First principles study on elastic properties and phase transition of NpN

Shibata, Hiroki; Tsuru, Tomohito; Hirata, Masaru; Kaji, Yoshiyuki

Journal of Nuclear Materials, 401(1-3), p.113 - 117, 2010/06

https://doi.org/10.1016/j.jnucmat.2010.04.006

The mechanical properties of neptunium nitride (NpN) were investigated using first principles calculations based on density functional theory that take the Spin-Orbit Coupling (SOC) effect into consideration. With NaCl, CsCl and ZnS structures in nonmagnetic (NM), ferromagnetic (FM) and antiferromagnetic (AFM) states, the structure of NaCl in all magnetic states and that of ZnS, excluding the NM state without SOC, were found to be mechanically stable. The bulk moduli, elastic constants, Young's moduli, Poisson's ratios and anisotropic factors of NpN in stable states were also estimated. The enthalpies of NpN for NaCl and ZnS structures revealed that the phase transition of NpN from ZnS structure to NaCl structure took place at a pressure of -7.32 GPa, and hence the phase transition of NpN in a cubic system does not occur at positive pressure.

Chloride complexation of Zr and Hf in HCl investigated by extended X-ray absorption fine structure spectroscopy; Toward characterization of chloride complexation of element 104, rutherfordium (Rf)

Haba, Hiromitsu*; Akiyama, Kazuhiko*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Yaita, Tsuyoshi; Hirata, Masaru; Sueki, Keisuke*; Nagame, Yuichiro

Bulletin of the Chemical Society of Japan, 82(6), p.698 - 703, 2009/06

https://doi.org/10.1246/bcsj.82.698

Chloride complexation of the group-4 elements Zr and Hf in 8.0-11.9 M HCl is investigated by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy to characterize chloro complexes of the transactinide element, rutherfordium (Rf). The complexes of Zr and Hf successively vary with the concentration of HCl from a hydrated complex [M(HO) ] at 8.0 M to a hexachloro complex [MCl] at 11.9 M (M = Zr and Hf). The present structural changes of the Zr and Hf complexes well reflect the previously studied anion-exchange behavior of Zr and Hf in HCl. From both the EXAFS and anion-exchange results, we suggest that Rf forms the same complexes as those of Zr and Hf in HCl, and that the complexation strength of the hexachloro complexes of the group-4 elements, [MCl] (M = Zr, Hf, and Rf), is in the sequence of Rf Zr Hf.

Extraction of actinides by multidentate diamides and their evaluation with computational molecular modeling

Sasaki, Yuji; Kitatsuji, Yoshihiro; Hirata, Masaru; Kimura, Takaumi; Yoshizuka, Kazuharu*

Proceedings of International Solvent Extraction Conference "Solvent Extraction-Fundamentals to Industrial Applications" (ISEC 2008), p.745 - 750, 2008/09

The multidentate diamides are synthesized and examined for the actinide (An) extractions, bi- and tridentate extractants are focused in this work. The extraction of actinide was performed from 0.1-6M HNO to organic solvents. It was obvious that tetraalkyl-diglycolamide (DGA) derivatives, (methylimino)bis(N,N-dioctylacetamide) (MIDOA) and dimethyl-dioctyl-2-(3-oxapentadecane)-malonamide (DMDOOPDMA) have relatively high D values (D(Pu): more than 70). The following notable results using DGA extractants are obtained, (1) DGA with short alkyl chain give higher D values than those with long alkyl chain, (2) DGA with long alkyl chain have high solubility in n-dodecane. The molecular modeling with computational chemistry was also used to elucidate the effects of structural and electronic properties of the reagents on their different extractabilities.

Application of the relativistic DV-X molecular orbital method to -uranium alloys with transition metals

Kurihara, Masayoshi*; Hirata, Masaru; Onoe, Jun*; Nakamatsu, Hirohide*

Progress in Nuclear Energy, 50(2-6), p.549 - 555, 2008/03

https://doi.org/10.1016/j.pnucene.2007.11.040

The alloying behavior of 4d and 5d transition metals (TMs) in -phase solid uranium (U) has been investigated using the discrete-variational Dirac-Fock-Slater (DV-DFS) method. We examined the d-orbital energy (Md value) of these TMs, the orbital overlap population (OOP) between the d-orbital of these TMs and the 5f or 6d orbital of -U, and the effective charge on each atom of the -U/TM alloy, and the effect of these parameters on alloying. It was found that the maximum solid solubility of TMs into -U was exponentially proportional to both the Md and the OOP (U5f-TMd and U6d-TMd). We found a good correlation between the MSS and Md, the effective charge, or OOP.

An Additional insight into the correlation between the distribution ratios and the aqueous acidity of the TODGA system

Sasaki, Yuji; Rapold, P.*; Arisaka, Makoto; Hirata, Masaru; Kimura, Takaumi; Hill, C.*; Cote, G.*

Solvent Extraction and Ion Exchange, 25(2), p.187 - 204, 2007/03

https://doi.org/10.1080/07366290601169345

Extraction of Eu(III) and Am(III) from HNO into the organic solvents using N,N,N',N'-tetraoctyl-diglycolamide (TODGA) was investigated in order to study the detailed extraction reaction. The chemical species: 1:2 for metal:TODGA complex is present in polar diluents. On the other hand, the metal complexes need three or more number of TODGA molecules to remain stable in non-polar diluents. The HNO concentration dependence on the distribution ratio suggests that HNO participates in the metal extraction. Infrared spectra indicate that the carbonyl oxygen coordinates with Eu(III), and luminescence lifetimes suggest that there is no water molecule in the inner coordination sphere of Eu-complex extracted.