RIKEN Accel. Prog. Rep. 50 (2017)

Ⅲ-3. Radiochemistry & Nuclear Chemistry

3URGXFWLRQDQGSXULILFDWLRQRI=UDQGP7H
T. Kubota,䠆1,䠆2 S. Yanou,䠆2 S. Shibata,䠆2 H. Haba,䠆2 and S. Takahashi䠆1resin (50-100 mesh Cl-form). The pentavalent of antimony
in c.HCl forms SbCl6- and strongly adsorbs onto anion
exchange resin, while H2TeO4, which has Te(VI), is notadsorbed. However, some fraction of tellurium wasadsorbed onto anion exchange resin, which could have beencaused by incomplete oxidation. In order to recovertellurium, the anion exchange resin was washed with amixture of c.HCl and 5% NaClO solution several times.
The radioactivity of 88Zr in the initial solution was 2.4
MBq excluding the radioactivity in the undissolved material,
which is the black residue. 88Zr completely remained in theorganic solution in the extraction with 0.5 M TTA andwashing with 0.1 M HCl, while yttrium completelyremained in the aqueous solution. This showed that a highpurity of 88Zr solution can be obtained. In the backextraction from 0.05 M TTA, 75% of 88Zr was extracted
into c.HCl in one process. This recovery rate is sufficiently
high; however, if necessary, the repeat of back extraction
would yield a higher value. The DF evaluated from thedistribution of 88Y, which is produced in the Y(d, 2np)
reaction, was greater than 104.
The radioactivity of 121mTe produced was 2.8 MBq. The
DF was 103 at most, and the recovery of tellurium was 50%.
Moreover, the low DF value of approximately 10 was often
obtained. This low recovery ratio and selectivity could be
ascribed to the redox reaction of antimony and tellurium,and further investigation is required. As another purification
method, solvent extraction methods are planned to beapplied.
In this investigation, 88Zr and 121mTe without the dilutionof naturally occurring isotopes were produced, and these
nuclides were purified. 88Zr was purified by solvent
extraction with TTA, while 121mTe was incompletelypurified by anion exchange chromatography.

Zirconium and tellurium are produced as a result ofnuclear fission. Experimental investigations of theirmigration in the environment are rarer than those of cesium,
strontium, and plutonium and require, if possible,carrier-free radionuclides, which mean they are undiluted
with naturally occurring isotopes. Such radionuclides can beproduced by bombardment with protons, deuterons, oralpha particles. In this report, we present investigations ofpurification methods for zirconium and tellurium fromyttrium and antimony, respectively, as target material.
Radionuclides, 88Zr and 121mTe, were produced at theRIKEN AVF cyclotron and transferred to the Kyoto
University Research Reactor Institute and then separated
from target materials, yttrium and antimony. The
purification was estimated by using the decontamination
factor, DF, which is defined as the ratio of the radioactivityof X in the initial sample to that in the purified sample,
where X is the target material, yttrium or antimony. The
radioactivity was determined by γ-spectrometry.
Zirconium-88 was produced by the bombardment ofyttrium foil (purity: 99%, size: 18 mm x 18 mm x 0.15 mm)with 24-MeV1) deuterons at 4.1 particle-μA for 2 h. 88Zr
was purified from an yttrium matrix by solvent extraction
after the by-product 89Zr decayed out to 89Y. The yttrium
foil was dissolved in c.HCl, and a black residue wasremoved by centrifugation. The supernatant was diluted to0.1 M HCl, which was used as the initial solution. 88Zr inthe initial solution was extracted into 0.5 M
2-thenoyltrifluoroacetone (TTA) in xylene.2) The xylene
solution was washed with 0.1 M HCl and diluted withxylene to 0.05 M TTA. 88Zr was extracted into c.HCl andthe aqueous solution was washed with cyclohexane toremove TTA. The c.HCl solution was vapored and then thesolution of 88Zr in 0.1 M HCl was prepared.
Tellurium-121m was produced by a bombardment of an
Sb2O3 pellet3) (diameter 15 mm), which was prepared bypressing Sb2O3 powder (purity 99.999%) at 3 t for 5 min,with deuterons. 121mTe was purified from an antimony
matrix by anion exchange chromatography.4) The Sb2O3
pellet was dissolved in c.HCl, following which NaClO wasadded to regulate the atomic valence to Sb(V) and Te(VI).
This oxidized solution was loaded onto anion exchange

䠆1䠆2References
1) M. S. Uddin et al., Radiochim. Acta. 95, 187 (2007).
2) H. Onish et al., Talanta. 19, 473 (1972).
3) S. Takács et al., Nucl. Instr. and Meth. Phys. Res. B. 278 93(2012).
4) D. Downs et al., J. Radio. Nucl. Chem. 262, 241 (2004).

Kyoto University Research Reactor Institute
RIKEN Nishina Center- 254 -