VIII-Ⅱ-1. Project Research
Project 2

PR2

Application Studies on Effective Use of F-Elements

H. Yamana
Research Reactor Institute, Kyoto University
1. Objectives and Allotted Research Subjects
Studies on actinide nuclides with careful management
are being more important for reprocessing, disposal,
partitioning, and transmutation processes in the nuclear
fuel cycle. Hot laboratory of KURRI is one of corefacilities in Japan, in which actinides especiallytransuranic elements (Pu, Am, Cm, and so on) can betreated. In our series of past research projects, separation,
purification, and synthesis procedures were found to beeffective for other elements, for example, rare metal
refining. In this context, the actinide studies are
expanded for fundamental and application studies on
f-elements. Allotted research subjects are as thefollowings.
ARS-1 Molecular dynamics simulation of molten salts
containing f-elements (N. Ohtori et al.)ARS-2 Spectroelectrochemical analysis of actinide ionsin molten salts and hydrate melts (A. Uehara etal.)
ARS-3 XAFS analysis on halogenides containing
actinides and FP elements (H. Matsuura et al.).
ARS-4 Study on chemical isotope effect of actinides
and fission product elements (T. Fujii et al.).
ARS-5 Systematic study on bonding characteristics oftrivalent actinides with ligands (A. Shinohara etal.).
ARS-6 Study on neutron capture cross sections oflong-lived nuclides by activation method (S.
Nakamura et al.).
ARS-7 Fundamental and application studies on
effective use of f-elements (Y. Ikeda et al.).
ARS-8 Study on complexation of actinides in aqueous
solutions (T. Sasaki et al.).
ARS-9 Electrochemical study of uranium inpyrochemical reprocessing system (Y. Sakamura
et al.).
ARS-10 Fundamental
studyonelectrolytic
formation/dissolution of f-element compounds
in molten salts (T. Goto et al.).
ARS-11 Absorption spectrophotometric study ontitanium in molten salts. (H. Sekimoto et al.)
ARS-12 Thermal and mechanical properties of actinides-

containing ceramics (S. Yamanaka et al.)2. Main Results and Contents
ARS-1 and 7 studied the U chemistry in low temperatureor room temperature melts. ARS-1 studied MD
simulation for concentrated LiCl aqueous solutions
containing uranyl chloride, and evaluated the local
structure of U. In ARS-7, the electrochemical behavior of(EMI)2UO2Cl4 (EMI: 1-ethyl-3-methylimidazoliun), in
the mixture of EMICl and EMIBF4 was studied and thebasic data were obtained. ARS-2, 3, 9, 10, and 11
studied the chemical behavior of actinides, lanthanides,
FP elements, and structural material elements in molten
salts, the results of which are to be dedicated to thedevelopment of nuclear fuel cycle or general industrialuse. ARS-2 studied electrochemical characteristics of
Am in micro litter order volume of molten LiCl-RbCl
eutectic. This is a first trial for using visible amount of
Am in high temperature melt at KURRI. In ARS-3 and
ARS-11, the electron absorption spectra of Nd were
measured. Effects of adding fluoride or borate wereclarified. ARS-9 studied reduction behavior of UCl3 on
Ni and Al electrodes in LiCl-KCl eutectic salt bath bycyclic voltammetry. Separation of U from Al was
discussed. ARS-10 studied electrochemical behavior andliquid structures of molten alkaline chlorides containing
Al. Raman spectra obtained were interpreted by using ab
initio method. ARS-4, 5, and 8 studied aqueous
chemistry of actinides and FP elements. ARS-4 studied
Pd complexation by ab initio method. Optimized
geometries of aqua- and chloro- Pd species were
calculated. ARS-5 studied solvent extraction of 99Mo.
Carrier-free 99Mo obtained from a Kyoto University
Reactor (KUR) multitracer was used. ARS-8 studied thetemperature effect of Th solubility. The Th solublity at
363 K was clarified. Nuclear physical properties of
TRUs were investigated in the study, ARS-6. By
activation method using KUR, the thermal-neutron
capture cross section of 243Am was newly evaluated. In
ARS-9, polycrystalline samples of Y6UO12 weresynthesized by solid state reactions. XRD, SEM, and
EDX data were successfully obtained.
3. Summaries of the achievements
In this research, by using various unique facilities of
KURRI for f-element research, new and characteristic
chemical and nuclear physical data were obtained. These
new information encompass solid chemistry, molten salt
and solution chemistry, as well as nuclear reactions of
f-elements. The results are useful either for scientificpurpose or for technological purpose for nuclear scienceand general industry.

ｆ－元素の有効利用に関わる基礎及び応用研究
採択課題番号 24P2
（京大・原子炉）山名 元

プロジェクトPR2-1

Local Structure around Uranyl Ion in Concentrated LiCl Aqueous Solutions

N. Ohtori, Y. Ishii, Y. Nagata, A. Uehara1, T. Fujii1,
H. Yamana1, K. Minato2 and Y. Okamoto2
Department of Chemistry, Niigata University
1
Research Reactor Institute, Kyoto University
2
Japan Atomic Energy Agency
INTRODUCTION: Electrochemical property of uranyl ion in aqueous solution highly concentrated by LiClis significantly different from that in the dilute solutions,and similar to that in the molten salt [1]. These highly
concentrated aqueous solutions are considered for theelectrolyte medium in the dry reprocessing of spent nuclear fuels, instead of high temperature molten salts. Recent experimental works [2,3] reveal that the local structure around uranyl ion in the concentrated solutions isintermediate between the dilute solutions and molten salts.
On the other hands, there is no report on the local structure in such concentrated solutions using simulation
techniques. In the present work, we have performed molecular dynamics (MD) simulation for LiCl aqueous solutions containing uranyl chloride, and evaluated the local
structure in the highly concentrated solution.

RESULTS: Figure 1 shows the self-diffusion coefficients in each solution. The calculated results are in good
agreements with the experimental result [7] for a whole
range of concentration. However, as shown in table.1, the
U-Cl distance and coordination numbers in 14M LiCl areunderestimated compared with the experimental results[3]. Figure 2 shows the Fourier transforms of experimental[3] and calculated EXAFS spectra. The calculated
U-Cl correlation shows very lower and more distancethan the experimental result [3]. These disagreements of
the local structure should be traceable to the insufficientinteratomic potential between uranyl ion and Cl ion.
Table.1 Coordination distances and numbers foruranyl ion in 14 M LiCl.
U-OH2
U-Cl
r/Å
N
r/Å
N
expt.[3]
2.47
1.3
2.73
2.4
this work
2.50
4
2.94
1
8

U-Oax

7

: expt.[3]: this work

3.0

,
,

2

1.5

D / 10 m s

2.0

-9

-1

2.5

,
,

: expt.[7]: this work

H2O
Cl

-

1.0
0.5
0.0

Li
0

+

2

4

6

8

10

12

14

3

CALCULATIONS: All the MD calculations havebeen carried out with NVE ensemble. The time step was
1.0 fs. The SPC/E model was used for water molecule,and the other ion models were cited from ref [4,5]. The
water and uranyl molecules were treated as rigid bodies
with SHAKE method. The LiCl concentration was set at
0, 1, 3, 5, 8, 14 M, and the concentration of uranyl chloride consistently at 0.05 M. After equilibrating the systems at 298 K, we evaluated the self-diffusion coefficient,radial distribution function, angular distribution function,and coordination number distribution in each solution. In
14M LiCl, the U LⅢ-edge extended X-ray absorption finestructure (EXAFS) spectrum was theoretically calculatedusing the FEFF code [6].

FT [ k  (k)]

6
5

U-Cl
U-Oeq

4
3
2
1
0
0

1

2

3

4

5

R+ / ÅFig.2 Fourier transforms of experimental
and calculated U LⅢ-edge EXAFS spectrain 14M LiCl.
REFERENCES:[1] A. Uehara, O. Shirai, T. Fujii, T. Nagai and H. Yamana,
J. Appl. Electrochem., 42, 455(2012).
[2] P. Allen, J. Bucher, D. Shuh, N. Edelstein and T. Reich,
Inorg. Chem., 36, 4676(1997).
[3] A. Uehara, T. Fujii, H. Matsuura, N. Sato, H. Yamana
and Y. Okamoto, OECD-NEA, 15, 197(2009).
[4] J. Greathouse, R. O’Brien, G. Bemis and R. Pabalan, J.
Phys. Chem. B, 106, 1646(2002).
[5] S. H. Lee and J. C. Rasaiah, J. Phys. Chem., 100,
1420(1996).
[6] A. L. Aukudinov, B. Ravel, J. J. Rehr and S. D. Conradson, Phys. Rev. B, 58, 7565(1998).
[7] K. Tanaka and M. Nomura, J. Chem. Soc. Faraday
Trans., 1, 83, 1779(1987).

cLiCl / M

Fig.1 Self-diffusion coefficients in LiClaqueous solutions.

採択課題番号 24P2-1 融体中での f-元素の分子動力学計算と実験系の照合研究
プロジェクト
（新潟大・理）大鳥範和、石井良樹、永田優太（京大・原子炉）上原章寛、藤井俊行、山名 元（JAEA）湊 和生、岡本芳浩

PR2-2

Electrochemical Measurement of Americium Ion in 0.1 ml Solution of High
Temperature Molten LiCl-RbCl Eutectic

A. Uehara, T. Nagai1, T. Fujii, K. Fukasawa2, T. Uda2
and H. Yamana
Research Reactor Institute, Kyoto University
Nuclear Fuel Cycle Engineering Lab., Japan Atomic
Energy Agency
2
Graduate School of Engineering, Kyoto University

1-2-2.E-04

I / x 104 (A)INTRODUCTION:
In currently proposed aqueous separation systems, inwhich dedicated extractants are used to extract trivalentactinides from High Active Waste (HAW), co-recovery ofAm and Cm is possible. However, a large separation
process, which is necessary for the removal of lanthanides from trivalent MAs, spoils the cost efficiency, and
it is practically impossible to separate Am from Cm.
Even in a pyrochemical reprocessing system, which isbased upon an electro-refining technique using molten
salt, Am/Cm separation is very difficult, because theirstandard redox potentials are very close. In this context,
this paper focuses attention to the possibility of Am isolation utilizing the divalency of Am, which can exist in
molten chloride melt. In the present report, we studied
electrochemical characteristics of Am in micro litter ordervolume of molten LiCl-RbCl eutectic
EXPERIMENTAL:
Solid Am oxide was dissolved into nitric acid and heated.
The solid Am(NO3)3 after drying up was dissolved into
LiCl-RbCl (55:45) eutectic melt at 773 K. Am(NO3)3 wasconverted to AmCl3 by purging Cl2 gas into the melt. In
the electrochemical measurements, about 0.015 mol%AmCl3 solutions of molten LiCl-RbCl was used. PYREX
glass membrane tube of 3 mm inner diameter was used
for the measurement. A 0.6 mm tungsten wire was used
for working and counter electrode, both covered withalumina sheath (Fig. 1).

with dry argon whose humidity and oxygen impurity wascontinuously kept less than 1 ppm.
RESULTS:
100 μl of sample solution ([Am] = 0.14 mol%) was used
for electrochemical measurements. Open circuit potential(EOCP) was monitored to estimate dissolving ions determining the equilibrium potential in the solution. Here, theequilibrium potential is depended on concentration andoxidation state of ions dissolving in the melt. EOCP
showed -1.08 V vs. Cl-/Cl2 which was positive enough to
the redox potential of Am. It has been reported that theelectrochemical of Am ion is similar to that of Nd as follows[1];
Am3+
+
e−
→
Am2+
(1)
Furthermore, generated Am2+ disproportionates to form
Am3+ and metallic Am,
3 Am2+⇄
2 Am3++Am(0)(2)
In order to study electrochemical behaviour of Am in
molten LiCl-RbCl eutectic, differential pulse voltammogram was measured. Three reduction peaks at -1.78, -2.12
and -2.90 V were observed. The peak at -2.90 V seems to
be close to the reduction potential of the Am3+|Am(0) couple, which is calculated based on the redox potential of
the Am3+|Am(0) couple in LiCl-KCl eutectic[2] and averaged polarizing power of the LiCl-RbCl eutectic [3].
Here, the redox potential was assumed to show linear
dependence on the averaged polarizing power of component cations of solvent melt consisted of the mole fraction,
the valence and the ionic radius of the solvent cations, Li+
and Rb+ in this case[3]. On the other hand, peaks at -1.78
and -2.12 V would be the reduction of iron and chromium
ion which would be impurity coming from the dissolutionof the sample tube.

-4.E-04-4-6.E-04-6-3.5

Fig.1 Working and counter electrodes (0.6 mm tungstenwire).
An Ag|Ag+ reference electrode composed with an Ag
wire|1 mol% AgCl in a bulk melt|PYREX glass membrane tube was used. Those two glass membrane electrodes were inserted into bulk LiCl-RbCl melt. Electrochemical measurement system HZ-5000 (Hokuto-Denko
Co. Ltd.) was used for the voltammetry measurements.
All the experiments were carried out in a glove box filled

-3

-2.5
-2
E (V vs. Cl-/Cl2)

-1.5

-1

Fig.2 Differential pulse voltammogram of Am in
LiCl-RbCl eutectic at 673 K.
REFERENCES:[1] A. Uehara, et al., J. Nucl. Mater. 414 (2011)336-339.
[2] M. Iizuka, et al., J. Nucl. Mater. 299 (2001) 32-42.
[3] K. Fukasawa, et al., J. Alloys Compds. 509 (2011)5112-5118.

採択課題番号 24P2-2 溶融塩及び水和物溶融体中におけるアクチノイドイオンの プロジェクト
分光電気化学的研究（京大・原子炉）上原章寛、藤井俊行、森山裕丈、山名 元（原子力機構）永井崇之

Effect of Fluoride Addition on UV-vis Spectra of Neodymium Cation in
Molten Chlorides

EXPERIMENTS: UV-vis spectroscopy of molten salts
containing neodymium cation has been carried out by
using the spectrophotometer (JASCO V-500) at the hotlabo in KURRI [2]. The solvent salts of LiCl-KCl or
NaCl-2CsCl was initially molten in a quartz cell (light
path: 1cm) installed in the argon circulated glove box andthe background absorption spectrum was measured. Then,
anhydrous neodymium chloride was added and electronic
absorption spectrum of neodymium was obtained by the
extraction of the background from the spectrum. In orderto look at the effect of fluoride in absorption spectra, LiF(upto 35 times of the molar concentration of neodymium)or NaF (upto 10 times of the molar concentration of neodymium) was added stepwisely to molten LiCl-KCl or
NaCl-2CsCl melts, respectively. Before the measurement, the molten salts containing fluoride were well confirmed that the mixtures were homogeneously mixed
without any bubbles in the light path.
RESULTS and DISCUSSION: It is well known thatthe evolution of hypersensitive transition in the electronic
absorption of neodymium is related to the indication of
the symmetric characteristics of 6 anions octahedral coordinated species around neodymium cation [3]. The
electronic absorption spectra of neodymium in molten
LiCl-KCl-LiF (Fig.1a) shows that with increasing the

Molar absorptivity [M-1 cm-1]

INTRODUCTION: Neodymium is one of the rareearths and it is widely used mainly as a neodymium
magnet. The neodymium magnet has the strongest magnetism among the permanent magnets and it has beenused as voice coil motors of hard disk drives and motors
in hybrid vehicles, electric vehicles, hybrid electric vehicles, wind farms and medical instruments which requiresof strong magnetism. The demand of neodymium increases along with increasing the demand of neodymium
magnets. However, over 90 % of the first resources ofrare earths including neodymium are now in China [1].
Although the price of neodymium tends to decrease recently, the lack of rare earths resources is a concern depending on the strategy of China. Therefore, we havefocused on used nickel misch metal hydride batteries as
the secondary resource of rare earths, and investigatedapplicability of molten salt electrolysis to extract neodymium. For the fundamental study, the electron absorption
spectraof
LiCl-KCl-NdCl3-LiF
andNaCl-2CsCl-NdCl3-NaF has been measured to investigate the correlation between the structure and the electrochemical behavior by the addition of fluorides.

Without LiF
LiF 2 times
LiF 4 times
LiF 6 times
LiF 8 times
LiF 10 times
LiF 15 times
LiF 20 times
LiF 25 times
LiF 30 times
LiF 35 times

(a)
10

5

0
560

-1

Research Laboratory for Nuclear Reactors,
Tokyo Institute of Technology
1
Research Reactor Institute, Kyoto University

concentration of LiF, the main absorption peak is slowly
shifted to the lower wavelength and new absorption
shoulder appears at ca 575 nm. Contrary to the case of
LiCl-KCl-LiF, the electronic absorption spectra in molten
NaCl-2CsCl-NaF (Fig.1b) shows much drastic effect depending on fluoride concentration, i.e. molar absoptivity
rapidly decreases until the concentration of 6 times to theneodymium and it seems saturated over this concentration. It can be clearly identified that the peak at ca. 575
nm is related the fluoride coodinated species. The reason of the difference of the tendency would be the synmetric characteristics of neodymium species and/or theeffect of the coulombic interaction between the cation
existing in 2nd coordination sphere (in this case Li+ orNa+) from neodymium. EXAFS and Raman spectroscopy
should be carried out to elucidate the complicated behaviour of fluoride addition effect before performing numerical calculation study.

10-1

H. Matsuura, K. Fujita, A. Nezu, H. Akatsuka,
H. Yamana1 and T. Fujii1

8

Molar absorptivity [M cm ]

PR2-3

570

580 590 600
Wavelength [nm]

610

620

Without NaF
NaF 2 times
NaF 4 times
NaF 6 times
NaF 8 times
NaF 10 times

(b)

6
4
2
0
560

570

580 590 600 610 620
Wavelength [nm]Fig.1 electronic absorption spectra of neodymium in
molten (a) LiCl-KCl-LiF and (b) NaCl-2CsCl-NaF.
REFERENCES:[1] T. Nishiyama: Rea metaru shigen (rare metal andminerals), Maruzen, (2009), 140.
[2] T. Fujii et al., J. Alloys Compd., 393 (2005) L1.
[3] Yu. A. Barbanel et al, J. Radioanal. Nucl. Chem., 143(1990) 167.

採択課題番号 24P2-3アクチニド元素及び FP 元素含有ハロゲン化物の XAFS 構造解析 プロジェクト（東工大・原子炉研）松浦治明、赤塚 洋、根津 篤（京大・原子炉）上原章寛、山名 元、藤井俊行

PR2-4

Chemical Isotope Effect of Actinides and Fission Product Elements

T. Fujii, S. Fukutani and H. Yamana
Research Reactor Institute, Kyoto University
INTRODUCTION: Palladium 107 (107Pd) is known as
one of long lived fission products. In order to know thenuclear properties of Pd isotopes, Nakamura andco-workers [1] have studied on neutron capture crosssection of 107Pd. The isotopic analytical technique ishelpful to understand the fractionation mechanism of Pd
isotopes in environmental samples and so on. In parallelwith the analytical studies, quantum chemical calculations are performed to check the validity of analyticalresults. The equilibrium constant of the isotope exchange
reaction can be theoretically obtained as the reduced partition function ratio (RPFR) of isotopologues. The RPFR
value is usually calculated through harmonic vibration
analysis. In this study, we report some ab initio calculations of hydrated Pd2+ complexes.
COMPUTATIONAL DATAILS: The orbital geometries
and vibrational frequencies of aqueous Pd(II) species
were calculated by using the density functional theory(DFT) as implemented by the Gaussian03 code. The DFT
method employed here is a hybrid density functional
consisting of Becke’s three-parameter non-local hybrid
exchange potential (B3) with Lee-Yang-and Parr (LYP)
non-local functionals. Similar to an ab initio study on
aqueous Pd(II) chlorides, we selected the basis sets. The
6-311+G** basis set (all-electron basis set) was chosen
for H, O, and Cl. An effective-core potential (ECP) basis
set, CEP-121G, was chosen for Pd. The detailed procedure can be seen elsewhere [2].
RESULTS: In order to evaluate the respective strength ofmass-dependent effects, we performed some quantum
chemical analysis calculations of the vibrational energiesof the aqueous Pd(II) species. It is well known that thecore structure of Pd(II) complex has the square-planar
structure via the hybrid orbital dsp2. The hydrated Pd2+
with the first coordination sphere is generally expressed
as Pd(H2O)42+. For this equatorial plane, two water molecules are arranged at the axial orientation. The shell including the first coordination sphere and the two watermolecules called "meso-shell." The Pd-O bond length forwater molecules at the axial positions is longer than thatat the equatorial positions. The two waters at the axial
position are stabilized by water molecules in second coordination sphere.
Calculation of the aqua complex was examined. We
performed structural analysis of Pd(H2O)42+ andPd(H2O)142+. Our calculation results are consistent withother calculation methods (see [2]). Isotope fractionationof Pd has been found in a chloride system [2]. The acidity
dependence of the fractionation [2] should be due to thedifference in the vibrational energy of Pd aqua- andchloro- complexes.

Fig. 1. Structure of Pd(H2O)142+.
The
structuresof
PdCln(H2O)4-n2-nand2-nPdCln(H2O)14-n (n = 0, 1, 2, 3, or 4) were optimized andthen intramolecular frequencies of these species were
calculated. The isotope enrichment factor due to the intramolecular vibrations can be evaluated from the reduced partition function ratio (RPFR) [3]. It was foundthat the complexation of Pd2+ with Cl- depress the RPFR
value.

Fig. 2. Reduced partition function ratio (RPFR) of
PdCln(H2O)4-n2-n (●) and PdCln(H2O)14-n2-n (■). n means
number of Cl- in first coordination sphere of Pd2+.
REFERENCES:[1] S. Nakamura et al., J. Korean Phys. Soc., 59, 1773
(2011).
[2] T. Fujii et al., Proc. Radiochim. Acta 1, 339 (2011).
[3] J. Bigeleisen and M. G. Mayer, J. Chem. Phys. 15,
261 (1947).

採択課題番号 24P2-4 アクチニド元素及び FP 元素の化学同位体効果に関する研究（京大・原子炉）藤井俊行、福谷 哲、山名 元

プロジェクトSolvent Extraction of Molybdenum from Hydrochloric Acid with Aliquat 336

Graduate School of Science, Osaka University
1
Faculty of Science, Osaka University
2
Radioisotope Research Center, Osaka University
3
Research Reactor Institute, Kyoto University

INTRODUCTION: Chemistry researches on heavyactinide and transactinide elements at the uppermost endof the periodic table are very important in inorganic
chemistry. Chemical properties of these elements are expected to be characteristic due to strong relativistic effects on their electronic shells. Chemical experimentsof these elements must be carried out on single atom
scale, because of their short half-lives and low production
rates in the nuclear reactions. It is, therefore, very difficult to perform chemical experiments of these elements.
The chemical experiments of the transactinide elements
have been performed mainly by simple partition methodand detection method is limited to an alpha-particle
measurement. In the chemical studies, the complex formation and chemical species of the transactinides were
investigated based on the comparison of its chemical behavior with those of lighter homologous elements.
In our previous study, we carried out solvent extraction ofmolybdenum (Mo) and tungsten (W), which were produced in nuclear reactions and transported by He/KCl
gas-jet system, in Aliquat 336/HCl system for chemistryof element 106, seaborgium (Sg) [1]. In this work, we
carried out solvent extraction of carrier-free Mo using
99
Mo obtained from a Kyoto University Reactor (KUR)
multitracer [2].
EXPERIMENTS: The 99Mo was separated from the
KUR multitracer by anion-exchange chromatography.
Solvent extraction of 99Mo was performed by mixing 1
mL of 2–11 M HCl solution containing 99Mo with 1 mL
of 0.011–0.23 M Aliquat 336 chloroform solution in a
polypropylene (PP) tube. The mixture was mechanicallyshaken for 30 min. After centrifuging the solution, thesame volumes of both the phases were pipetted in separate PP tubes and then were subjected to -ray spectrometry with a Ge semiconductor detector. Distribution ratio(D) was determined from the radioactivity of 99Mo. The
D values were determined using the equation:
D = AorgVaq/AaqVorg (1)where A represents the radioactivity and V represents thevolume of the solution. The subscripts “aq” and “org”
denote the aqueous and organic phases, respectively.
RESULTS: The variations of the D values of Mo as afunction of HCl concentration at 0.05 M of Aliquat 336
are shown in Fig. 1. The D values are good agreementwith those in Ref. [1] at 8 and 11 M HCl solutions.
However, the D values were higher than those in Ref [1]at 2 and 5 M HCl solutions. In the previous experimentwith the shaking time of 3 min, chemical reactions in theextraction would not be in equilibrium in lower than 5 M
of HCl.
We investigated the relationship between the D value andAliquat 336 concentration at 11 M of HCl to determine
the net charge of the extracted Mo complex. The result isshown in Fig. 2. The linear relationship between logD
and log[Aliquat 336] is observed. The slope value of thelinear line is 1.0 ± 0.1. The present data indicate that anionic complex of Mo with net charge of −1 would be extracted into Aliquat 336 chloroform solution from 11 M
HCl solution. The [MoO2Cl3]− complex can be suggested
based on Ref. [3].
10

1

D

T. Yokokita, Y. Kasamatsu, N. Shiohara1, N. Takahashi, T.
Yoshimura2, K. Takamiya3 and A. Shinohara

0.1

0.01
0

This work
Ref. [1]2468[HCl] / M

10

12

Fig. 1. Variation of the D value of 99Mo as a function of
HCl concentration at 0.05 M of Aliquat 336.
2.5
2
1.5

logD

PR2-5

1
0.5
0

-0.5
-1
-2

-1.5
-1
-0.5
log[Aliquat 336]

0Fig. 2. Variation of the D value of 99Mo as a function of
Aliquat 336 concentration at 11 M of HCl.
REFERENCES:[1] K. Ooe et al., Proc. Radiochim. Acta., 1 (2011)127-129.
[2] K. Takamiya et al., J. Nucl. Radiochem. Soc., 1(2000) 81-82.
[3] F. Jaliehvand et al., Inorg. Chem., 46 (2007)
4430-4445.

採択課題番号 24P2-5 重・超アクチノイド元素の化学実験に向けた基礎研究
プロジェクト（阪大院・理）横北卓也、笠松良崇、高橋成人、篠原 厚（阪大・理）塩原直也 (阪大・RI セ)吉村 崇（京大炉）高宮幸一

PR2-6

Measurements of Neutron Capture Cross Sections for Radioactive Nuclei

S. Nakamura, F. Kitatani, T. Fujii1, A. Uehara1 andH. Yamana1
Japan Atomic Energy Agency
Research Reactor Institute, Kyoto University

1

INTRODUCTION: A series of experiments withthe activation method has been performed to measurethermal-neutron capture cross-sections and resonanceintegrals of Minor Actinides (MAs), ex. 237Np, 244Cm
241
Am and so on. Americium-243 is one of the important
MAs, because it has long half-life (7370yr) and products
higher Cm isotopes via neutron capture reaction, i.e.
244
Cm, 245Cm, and 246Cm. However, there still exist large
discrepancies among reported data of the thermal-neutron
capture cross-section (0) as shown in Fig.1. This situation might affect the prediction of the amount of productnuclides. This work reports the situation of the measurements and analysis for the neutron capture cross-sectionof the 243Am(n,) reaction.

Fig.2 An example of -ray spectrum of 243Am sample
ANALYSES: When analyzing the spectral data, there
was the problem that the -ray emission probabilities
have about 30% errors [1]. The 244Am ground state decays to the 6+ state of 244Cm by the probability of 100%via- decay[2]. There is no transition from the isomer toground states of 244Am. Using this scheme, emission
probabilities could be derived straightforward form theratios of -ray yields for 154, 744 and 898 keV as follows:

Fig.1 Situation of the reported data for 0
EXPERIMENTS: Adequate amount of a high-purity
243
Am standardized solution (999Bq) was prepared for anirradiation sample. Its amount was measured with analpha spectrometer, EG&G ORTEC SOLOIST alpha
spectrometer. The irradiation for the 243Am sample was
performed for 1 hour at the Pn-2 of the KUR. Pieces of
Au/Al and Co/Al alloy wires were irradiated together
with the Am sample to monitor neutron flux components
at the irradiation position. A high-purity Ge detector wasused to measure the  rays emitted from the Am sample
and wires to obtain their induced activities. Figure 2
shows an example of -ray spectrum of 243Am sample.
Decay  rays emitted from 244gAm (10.1h) were observedat the energies of 154, 744 and 898 keV.

With this idea, we found the possibility that the emission
probabilities of gamma rays would be improved greatly
from 30% error to a few %. In this preliminary experimentpreliminary, the decay gamma-rays were not followed. In
the future experiment, we schedule that the irradiation timeis lengthened, and the decay gamma rays are measured
enough. It is expected to be able to improve the accuracyof the cross section of 243Am by re-measuring the gamma-ray emission probabilities.
REFERENCES:[1] R.W.Hoff et al., Phys. Rev. C.29,618 (1984).
[2] S.E.Vandenbosch et al., Nucl. Phys., 30,177 (1962).

採択課題番号 24P2-6放射化法による長寿命核種の中性子断面積研究（原子力機構） 中村詔司、北谷文人（京大・原子炉）藤井俊行、上原章寛、山名 元

プロジェクトPR2-7 Elecrochemical Properties of Uranyl Species in 1-Ethyl-3-Methylimidazolium Nitrate
K. Sasaki, M. Harada, T. Suzuki and Y. Ikeda[UVO2(NO3)4]3- → [UVIO2(NO3)4]2- + e-

Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology[UIVO2(NO3)n](n-4)- → [UVIO2(NO3)4]2- + 2e- (Epa2)(

EXPERIMENTS:
EMINO3 and [EMI]2[{UO2(NO3)2}2(4-C2O4)] were synthesized based on the reported method [9]. The syntheses of these compounds
were confirmed by using NMR and single crystal X-ray
analytical methods. Cyclic voltammetry were carried out
using BAS ALS model 660B. A three-electrode system
was used for preventing the ohmic drop, i.e., a working
electrode: glassy carbon, a counter electrode: Pt, a reference electrode: Ag/AgCl (a liquid junction filled with
EMINO3).
RESULTS: UV-visible absorption spectrum of EMINO3 solution dissolved [EMI]2[{UO2(NO3)2}2(4-C2O4)].
The absorption spectrum was found to be similar to thatof DMINO3 solution dissolved [DMI]2[UO2(NO3)4](DMI = 1.3-dimethylimidazolium). This suggests that theuranyl species in EMINO3 solution dissolved[EMI]2[{UO2(NO3)2}2(4-C2O4)] exist as [UO2(NO3)4]2-.
Figure 1 shows the cyclic voltammograms of EMINO3
solution dissolving [EMI]2[{UO2(NO3)2}2(4-C2O4)]
measured at various scan rates (v). As seen from Fig. 1,
one reduction and two oxidation peaks are observed ataround -0.5 (Epc), -0.3 (Epa1), and 0.03 V (Epa2), respectively, and the peak at around 0.03 V disappear with increasing the scan rate. Furthermore, it was found that the
Epc - Epa1 values increase with an increase in the scan rate
and that the plot of peak currents of Epc vs. v1/2 gives alinear relationship. From these results, it seems likely thatthe present reaction proceeds through following mechanism.
(Epc).

2[UVO2(NO3)4]3- → [UVIO2(NO3)4]2- + [UIV(NO3)n](n-4)-

However, the chemical form of uranyl species in EMINO3 must be examined in more detail.
-20

0

Current i/µA

INTRODUCTION: Room temperature ionic liquids(ILs) are expected to be useful media for recovering uranium from spent nuclear fuels and solid wastes contaminated with uranium [1]. Hence, the extraction behavior of
uranyl species from aqueous to IL phase, the electrochemical behavior of uranyl species in ILs, and so on
have been studied [2-8]. In the present study, we haveexamined the structure and electrochemical behavior of
uranyl(VI) species in EMINO3 (EMI = 1-ethyl3-methylimidazoliun).

[UVIO2(NO3)4]2- + e- → [UVO2(NO3)4]3-(Epa1)

20

0.05V/s

s

40

60

0.3
-80 -6
80x10

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

Potential E/V vs. Ag/AgCl

Fig. 1. Cyclic voltammograms of the solution prepared by dissolving [EMI]2[{UO2(NO3)2}2(4-C2O4)](1.01 × 10-2 M) into EMINO3 measured at different scanrates (ν = 0.05 ~ 0.3V/s). Initial scan direction: cathodic. Temp. = 65 ºC.
.
REFERENCES:[1] V. Cocalia, K. Gutowski, and R. Rogers, Coord.
Chem. Rev., 250, 755 (2006).
[2] K. Binnemans, Chem. Rev., 107, 2592 (2007).
[3] I. Billard and C. Gaillard, Radiochim. Acta, 97, 355(2009).
[4] Y. Ikeda, K. Hiroe, N. Asanuma, and A. Shirai, J.
Nucl. Sci.Technol., 46, 158 (2009).
[5] A.-V. Mudring and S. Tang, Eur. J. Inorg. Chem.,
2010, 2569.
[6] T.J. Bell and Y. Ikeda, Dalton Trans., 40, 10125(2011).
[7] X. Sun, H. Luo, and S. Dai, Chem. Rev., 112, 2100
(2012).
[8] P.R. Vasudeva Rao, K. A. Venkatesan, A. Rout, T.G.
Srinivasan, and K. Nagarajan, Sep. Sci. Technol., 47, 204(2012).
[9]A.E. Bradley, C. Hardacre, et al., Inorg. Chem., 43,2503 (2004).

採択課題番号 24P2-7f-元素の有効利用に関わる基礎及び応用研究（東工大・原子炉）佐々木琴江、鈴木智也、原田雅幸、池田泰久

プロジェクトPR2-8 Temperature Effect on the Solubility and Solid Phase Stability of Thorium Hydroxide
T. Kobayashi, T. Sasaki and H. Moriyama1

maximum intensity (FWHM) in radian, and the Bragg
angle.

Graduate School of Engineering, Kyoto University
1
Research Reactor Institute, Kyoto University

EXPERIMENTS: A Th stock solution diluted to obtain sample solutions, and pH value was adjusted by
HClO 4 /NaOH. The sample solutions were placed into anoven controlled at 90°C and kept for given periods. After
aging, the sample solutions cooled down to 25 ºC and thepH values measured. The supernatant was filtered (3k 100k Da filter, Millipore) and Th concentration determined by ICP-MS (HP4500, Hewlett Packard). The detection limit was about 10−8 M. The solid phase was analyzed by X-ray diffraction (XRD) measurement (RINT
2000, RIGAKU).
RESULTS: Fig. 1 shows the Th(IV) solubility after
heating at 90 ºC at ionic strength (I) = 0.1, together withthe solubility of Th(OH) 4 (am) kept at 90 and 25 ºC [1,2].
The solubility after heating at 90 ºC for 7days starts todecrease compared to those at 25 ºC, and the values after
41 days are approximately 3 orders of magnitude lower
than those of Th(OH) 4 (am) kept at 25 ºC. Analyzing thesolubility data after heating, the solubility product values
were determined.
In the XRD spectra of the solid phases, broad peaks
corresponding to ThO 2 (cr) were observed, indicating the
crystallization of the initial Th(OH) 4 (am). It is note thatseveral sharp peaks (2θ = 30.0, 31.2, 37.2, 39.6, and 47.5
º at I = 2.0) attributed to NaClO 4 , which was used asback electrolyte. As the peaks 2θ = 27.6, 45.9 and 54.4 º
attributed to ThO 2 (cr) and the particle size (D) of solid
phase was calculated using Scherrer equation:
D = Kλβ cos θ(1),

Fig. 1 Th solubilty after heating at 90 ºC (3kDa)

I = 0.5, pH = 5.6, 3 days

Relative Intensity

INTRODUCTION: Safety assessment of geologicaldisposal requires a prediction of solubility limit of tetravalent actinide (An(IV)) over a considerable time-spanmore than 100 thousands of years. An(IV) is easily hydrolyzed to form amorphous hydroxide (An(OH) 4 (am))
which controls the solubility limit. However, meta-stable
An(OH) 4 (am) is potentially stabilized to more thermodynamically stable crystalline oxide (AnO 2 (cr)) during
extremely long period of disposal or under relevant elevated temperature condition in the disposal site. In thepresent study, we focused on the solubility and solid
phase stability of thorium (Th(IV)) hydroxide after heating at 90°C. Th solubility was measured and the solubility product correlated to the particle size of solid phase.

I = 0.5, pH= 7.5, 39 days
I = 0.1, pH = 5.4, 7 days
I = 2.0, pH = 3.7, 7 days

ThO2 (cr)

20

30

40

50
60
2θ Cu-Ka

70

80

90

Fig. 2 XRD spectra of Th solid phase after heating at 90ºC
The relationship between obtained solubility productvalue and particle size of the solid phase after heating arein agreement with the Schindler equation [3], where thesolubility product decreases with increasing particle size.
This work exemplifies the predicted transformation of
amorphous phase into a thermodynamically more stablephase, and therefore less soluble solid of higher crystallinity. This finding adds highlight to understand an important mechanism relevant for predicting actinide solubility at repository conditions.

REFERENCES:[1] Rai et al. Radiochim. Acta 88, (2000) 297.
[2] Kobayashi et al. J. Nucl. Sci. Technol. 46, (2009)1085.
[3] Schindler, P. W., Adv. Chem. Ser., 67, (1967) 196.

where K, λ, β, and θ represent Scherrer constant, X-ray
wavelength (Cu-Ka), the line broadening at the half

採択課題番号 24P2-8 アクチニド元素の水溶液内錯生成反応に関する研究
プロジェクト（京大院・工）佐々木 隆之、小林 大志、上田 健揚、伊達 海斗、松浦 由佳、上村 拓也（京大・原子炉）藤井 俊行、山名 元

Reduction Behavior of UCl3 on Ni and Al Electrodes in
LiCl-KCl Eutectic Melt at 773 K

Y. Sakamura, M. Iizuka, K. Uozumi, T. Fujii1, A. Uehara1
and H. Yamana1
Central Research Institute of Electric Power Industry
Research Reactor Institute, Kyoto University

1

INTRODUCTION:
Electrorefining process using
molten chloride salt bath is under development worldwide for nuclear fuel cycle. Actinides contained in spent
nuclear fuels are dissolved into the salt at the anode, andthen are collected at the cathode. Liquid Cd cathode isemployed to collect Pu together with U and minor actinides (Np, Am and Cm). Because of chemical similarity,some of rare earth fission products are also deposited in
the Cd cathode. Since Ni and Al form intermetallic compounds with actinides, they are expected to be an alternative for the cathode material to enhance the separation
factor between the actinides and rare earths. The Ni
cathode has been studied to separate Dy from Nd contained in used Nd magnets [1], and the Al cathode has
been studied for the electrorefining process of spent nuclear fuels [2]. In this study, reduction behavior of UCl3
on Ni and Al electrodes in LiCl-KCl eutectic salt bath areinvestigated by cyclic voltammetry.
EXPERIMENTS: LiCl-KCl eutectic melt was contained by a high-purity alumina crucible at 773 K, wherea working electrode of Ni, Al or W wire (1 mm diameter),a counter electrode of glassy carbon rod (3 mm diameter),a Ag/AgCl reference electrode and a type-K thermocouple were placed. The W wire was employed as the inert
electrode because W metal does not form any alloys with
U or Li metal. The Ag/AgCl electrode consisted of a Ag
wire immersed in a LiCl-KCl eutectic salt mixture with 1
wt% AgCl, which was contained in a closed-end Pyrex
tube. The potential used in this paper is relative to the
Ag/AgCl potential, unless otherwise stated. The potentialof the Ag/AgCl electrode was 2.407 V against a Li metalelectrodeposited on a Ni wire. The concentration of UCl3
was incrementally changed by adding a prepared
LiCl-KCl-UCl3 salt whose U concentration was 11.4 wt%
determined by ICP-AES analysis. All the measurements
were conducted in a high-purity Ar atmosphere glove box(H2O, O2 < 1 ppm).
RESULTS: The blank test was conducted in a LiClKCl eutectic alone. The cyclic voltammogram (CV) of Al
has a cathodic current peak rising at about -1.9 V, whichshould correspond to the formation of Li-Al alloy. As for
the CVs of Ni and W, no cathodic current is observed in
the potential range more positive than -2.4 V where Li
metal is deposited.
Figure 1 shows typical CVs of the Ni, Al and W electrodes in a LiCl-KCl-UCl3 (0.16 mol%) melt. The working electrode potential was first scanned from the rest
potential to -1.6 V and then was reversely scanned. The

採択課題番号 24P2-9

CV of W indicates that reduction of U3+ to U metal occurred by a one-step process for the reduction wave at-1.45 V, followed by reoxidation of the deposited U metalat the electrode surface during the anodic sweep.
On the Ni electrode, a small cathodic current corresponding to the formation of U-Ni alloys rises from -1.25
V. In addition to the anodic peak for reoxidation of thedeposited U metal, there are several anodic peaks, whichindicates that U dissolves from the different U-Ni alloys.
Several alloys (UNi6, UNi2, U5Ni7, U7Ni9 and U6Ni) are
shown in the phase diagram of U-Ni system [3]. Besides,
two anodic currents located at around 0.2 V and 0.0 V
should correspond to the U3+/U4+ and Ni/Ni2+ couples,
respectively. It is noted that the anodic peaks for oxidation of the U-Ni alloys are much smaller than that of thepure U metal. Hence, the formation reaction of U-Ni alloys is relatively slow compared with the rare earth-Ni
systems [1].
The rest potential of the Al electrode, around -1.03 V,
is more negative than those of the Ni and W. In the CV of
Al, the cathodic current rises from the rest potential,
which is attributed to the formation of U-Al alloys [2].
The cathodic current peak for pure U metal deposition is
also observed at -1.45 V. It is indicated that the formation
reaction of U-Al alloys is faster than that of U-Ni alloys.
The anodic current rising steeply from -1.03 V should be
due to the dissolution of U and Al from the U-Al alloys.
Therefore, it is suggested that U cannot be separated from
Al by the anodic dissolution of U-Al alloys.
24
W
Al
Ni

W

18

Current (mA)

PR2-9

Al

12

6

Ni

0
-6

-12

-1.6

-1.2
-0.8
-0.4
Potential (V vs Ag/AgCl)

0.0

Fig. 1
CVs of W (1 x 5 mm), Al (1 x 7 mm), and Ni(1 x 5 mm) wire electrodes in LiCl-KCl eutectic melt
containing 0.16 mol% of UCl3 at 773K. Scan rate 0.1 V/s.
REFERENCES:[1] H. Konishi et al., Molten Salts, 54(1), 21 (2011) [inJapanese][2] P. Soucek et al., Proc. Int. Conf. Global 2009, pp.
1156, Paris, France, Sept. 6-11, 2009.
[3] T. B. Massalski, Binary Alloy Phase Diagrams, Vol. 2,
American Society for Metals, Metals Park, OH, 1986

溶融塩化物中でのウランの酸化還元挙動に関する
プロジェクト
乾式再処理基礎研究（電中研）坂村義治、飯塚政利、魚住浩一（京大・原子炉）山名 元、藤井俊之、上原章寛

PR2-10

Electrochemical Behavior of f-Elements Compound

T. Goto and K. Hachiya1
Department of Environmental Systems Science, Facultyof Science and Engineering, Doshisha University
1
Department of Fundamental Energy Science, Graduate
School of Energy Science, Kyoto University

INTRODUCTION: Molten salts are promising media
for separation and recovery of the spent nuclear fuel. To
realize the process, clarifying the physicochemical properties of FP elements in molten salts is required. Althoughcesium is known as an important fission product, little
has been reported about its effect on the molten salts.
From the background, we have examined the influencethat the existence of the cesium ion gave to other multivalence ions in molten LiCl-KCl. In this report, aluminum ion was selected as model of a multi valence cationand electrochemical behavior and liquid structures ofmolten alkaline chlorides containing Al were investigated.
EXPERIMENTS:
The LiCl-KCl-CsCl eutectic(LiCl-KCl-CsCl=57.5:13.3:29.2 mol %) was used as anelectrolyte for electrochemical measurement. AlCl3 wasdirectly added to the melt as an Al(Ⅲ) source. All experiments were conducted in an argon atmosphere with acontinuous gas refining instrument. A tungsten wire electrode covered with a high purity alumina tube was used
as a working electrode for investigating electrochemical
behavior of aluminum ions. Diffusion coefficient of aluminum ions was determined by means of electrochemicalmeasurement. Raman scattering spectra were obtainedfor AlCl3, LiCl-KCl eutectic melt +3mol% AlCl3,
LiCl-KCl-CsCl eutectic melt + 3 mol% AlCl3,
NaCl-AlCl3 1:1 melt. Simulated Raman spectra were also
attained through density-functional-theory calculations
with GAUSSIAN 09.
RESULTS: Diffusion coefficient of Al( Ⅲ ) in
LiCl-KCl-CsCl at 603 K was determined to be 4.0×10-8
cm2 s-1. The diffusion coefficient was 3 orders lower thanthat in LiCl-KCl. This implied the coordination of aluminum ion in the molten salts was affected by the existence of the cesium ion. Raman spectroscopy was carriedout to characterize the melt structures. Experimental andcalculated Raman spectra are given in Figs. 1 and 2. A
hybrid functional, B3LYP, was used for exchange-correlation
functional,
and6-311G**,
6-311++G**, and aug-cc-pVTZ were used for basis
functions. Finite-temperature liquid structure was also
analyzed through atom-centered density matrix propaga-

採択課題番号 24P2-10

tion (ADMP) simulation, a variant of ab-initio molecular
dynamics simulations, with split valence basis functionof m-def2-SVP and HSEh1PBE hybrid correlation-exchange functional for 1:1 CsCl-AlCl3 mixture at
700 K. As have been reported and discussed [1], AlCl4cluster structure is expected for anion in basic and neutral
molten aluminum–alkaline-metal chloride mixtures. Our
calculation basically confirmed the dominance of AlCl4at neutral condition, but transient existence of Al2Cl7was also observed as have been reported for other aluminum–alkaline-metal chloride melts [2].

Fig. 1 Raman scattering spectra for molten AlCl3 at 573
K.

Fig. 2 Simulated Raman scattering spectra for Al2Cl6
cluster.
REFERENCES:[1] M. P. Tosi, D. L. Price, M.-L. Saboungi, Annu. Rev.
Phys. Chem., 44, 173 (1993).
[2] M. Salanne, L. J. A. Siqueira, A. P. Seitsonen, P. A.
Madden, B. Kirchner, Faraday Discuss., 154, pp.
171-188 (2012).

溶融塩中における f-元素化合物の電気化学的形成・溶解に関する基礎研究（同志社大・理工）後藤琢也（京大院・エネ科）蜂谷 寛

プロジェクトPR2-11

Characterization of Neodymium Ion in Molten CaCl2
in Equilibrium with Neodymium Triborate, NdB3O6

H. Sekimoto, A. Uehara1, T. Fujii1 and H. Yamana1
Department of Materials Science and Engineering, Faculty of Engineering, Iwate University
1
Research Reactor Institute, Kyoto University

equilibrium with NdB3O6 using the absorption spectra.
The calibration curve of the concentration of neodymium
ion was prepared using the absorbance at 590 nm. Using
the calibration curve, the concentration of neodymium
ion in equilibrium with the mixture of NdB3O6 and B2O3
at 800 C was estimated to be 0.3  0.1 mol kg-1 in molality.

INTRODUCTION: Development of recycling technique for neodymium magnet is essentially important toachieve sustainable society. Consequently, we propose
and are investigating a new recycling process of neodymium magnet shown in Fig. 1. In the proposed process,the neodymium magnet is melted together with sufficientamount of B2O3 in graphite crucible to form molten ironbased alloy and Nd2O3-B2O3 slag, which is recovered anddissolved in molten salt. And then, Fe-Nd-B alloy is produced by molten salt electrolysis. In this study, as the firststage of the research on the molten salt electrolysis in the
proposal, we investigated the dissolution behavior of neodymium triborate, NdB3O6, which is the main component of recovered Nd2O3-B2O3 using absorption spectroscopy.
EXPERIMENTS: The absorbance of CaCl2 molten
containing a given amount of dissolved NdCl3 at 800 C
was measured to obtain the absorption spectrum of trivalent neodymium ion. And then, we measured the absorption spectrum of trivalent neodymium ion in CaCl2 molten salt in equilibrium with the mixture of NdB 3O6 andB2O3 which is prepared by melting 5.7 g of Nd2O3 and4.3 g of B2O3 in graphite crucible at 1200 C.

Nd2O3 in NdB3O6 + 3CaCl2  2NdCl3 + 3CaO . (1)

-1

4.0

Absorbance, A / cm

RESULTS: Figure 2 shows the absorption spectra oftrivalent neodymium ion in CaCl2 molten salt at 800 C.
The broken lines were obtained as the results of themeasurement of the absorbance of NdCl3 dissolved in
CaCl2 molten salt. The spectra are similar to the absorption spectra of neodymium chloro complex ion in
LiCl-KCl eutectic molten salt at 600 C obtained by Fujii
et al. [1] On the other hand, the solid line corresponds
absorption spectrum of the neodymium ion in equilibriumwith the mixture of NdB3O6 and B2O3 and NdCl3. The
shape of the spectrum is the same as the spectra of chloro
complex ion obtained by the measurement of the absorbance of NdCl3 dissolved in CaCl2 molten salt. This result
indicates that the neodymium ion in NdB3O6 dissolved in
CaCl2 molten salt as chloro complex ion. Supposing that
NdB3O6 is the mixture of Nd2O3 and B2O3 (where themolar ratio of Nd2O3 to B2O3 is 1/3), the dissolution reaction of neodymium ion in CaCl2 from NdB3O6 is considered to be represented by the following reaction,

Fig. 1. Flowchart of the recycling process for neodymium magnet proposed in this study.

3.5

mNdCl = 0.247 mol kg

3.0

Nd(III) in equilibriumwith NdB3O6 and B2O3

2.5
2.0

-1

3

mNdCl = 0.114 mol kg

-1

3

-1
1.5 m
= 0.038 mol kg
NdCl3-1
1.0 mNdCl = 0.000 mol kg
3

0.5
0.0
-0.5
300

400

500

600

700

800

Wavelength,  / nm
Fig. 2. Absorption spectra of trivalent neodymium
ion in CaCl2 molten salt at 800 C.
REFERENCES:[1] T. Fujii, H. Moriyama and H. Yamana, J. Alloy.
Compd., 351 (2003) L6-L9.

We then estimated the concentration of neodymium ion in

採択課題番号 24P2-11

吸収分光測定を用いた高温融体中の金属イオンの溶存形態に関する研究（岩手大・工）関本英弘 （京大原子炉）上原 章寛、藤井 俊行、山名 元

プロジェクトPR2-12

Thermal and Mechanical Properties of Actinides-Containing Ceramics- Synthesis of Y6UO12 -S. Yamanaka, Y. Ohishi, H. Muta and K. Kurosaki(1966).

Graduate School of Engineering, Osaka University

INTRODUCTION: The ceramic nuclear waste form
has been considered as one of the methods to immobilize
actinide elements extracted from high-level radioactive
nuclear wastes. Among them, in recent years Y6AnO12
and Yb6AnO12 where An represents actinide elements
have received attention as appropriate ceramics in which
actinide elements can be immobilized stably. When utilizing such ceramics as the waste form, the physical andchemical properties should be understood. However theproperties of Y6AnO12 and Yb6AnO12 have been scarcely
reported. Previously, our group has investigated thethermal properties of Y6WO12 and Yb6WO12 [1] because
Y6WO12 and Yb6WO12 take the same hexagonal crystal
structure as that of Y6AnO12 and Yb6AnO12 [2].In the present study, polycrystalline samples of Y6UO12 were synthesized by solid state reactions.
EXPERIMENTS: Y6UO12 was prepared from the
mixtures of Y2O3 and U3O8 by standard solid-state reactions. U3O8 was prepared by heating UO2 in flowing air
at 873 K for 6 h. Dried Y2O3 powders (Kishida ChemicalCo., 99.99%) and U3O8 powders were weighed in theappropriate molar ratio and mixed thoroughly in an agate
mortar. These oxide mixtures were pressed into pellets at
150 MPa for 5 min at room temperature. The green pellets were then heated in air on an alumina crucible for 24
h at 1673 K. The crystal structure of the samples wasanalyzed by powder X-ray diffraction (XRD) using
Cu-K radiation. The microstructure and the element
distribution of the samples were analyzed by the scanningelectron microscopy (SEM) and the energy dispersive
X-ray (EDX) analysis at room temperature.

Fig.1 XRD pattern of Y6UO12 sample, together with thepeak positions reported in the literature.

RESULTS: Figure 1 shows the XRD pattern of theY6UO12 sample, together with the peak positions reported
in the literature. In the XRD pattern, there were no peaks
derived from impurities. As shown in Fig. 2, the SEM
images revealed that the surface of the Y6UO12 sample
was homogeneous with no secondary impurity phases.
The quantitative EDX analyses confirmed that the chemical compositions did not deviate a lot from the starting
compositions. These results indicate that the single phasematerial was synthesized in the present study.
REFERENCES[1] Y. Zheng et al., “Thermal conductivity of Y6WO12,and Yb6WO12 ceramics,” J. Nucl. Mater., 419, 357-360(2011).
[2] S. F. Bartram, “Crystal structure of the rhombohedral
MO3R2O3 compouds (M = U, W, or Mo) and their relation to ordered R7O12 phases,” Inorg. Chem., 5, 749-751

Fig.2 SEM and EDX images of Y6UO12 sample.

採択課題番号 24P2-12
アクチニド含有酸化物の物性に関する基礎研究（阪大・工）山中伸介、黒崎 健、牟田浩明、大石佑治

プロジェクト