CO9-1

Study on the Production and Chemical Separation Methods ofTechnetium as an Assay Tracer

T. Kobayashi, S. Sekimoto1 and S.Shibata1
College of Humanities and Sciences, Nihon University
Research Reactor Institute, Kyoto University

1INTRODUCTION: Technetium with atomic number
43 is an artificial radioactive element that is not found innature, and it is used as a tracer in medicine and environmental analysis. In particular, technetium-95m(half-life: 61 days) and technetium-99m (half-life: 6hours) are frequently used as tracers. Because commercially available technetium-95m is isolated from fissionproducts, the influence of other technetium isotopes cannot be avoided. Technetium-99m, however, is obtained asa decay product of molybdenum-99, and it does not sustain any effects from other technetium isotopes. Technetium-99m, therefore, is superior as a tracer with its higher
isotopic purity compared to technetium-95m. Nonetheless, the supply of technetium-99m from overseas has
recently been unstable. Consequently, a variety of alternative efforts have been examined in Japan, such as thestudy of production methods using accelerators. The
present research employed molybdenum metal to production molybdenum-99/technetium-99m through reactor
neutron irradiation. The handling of molybdenum metal
is easy, but the generated specific radioactivity is low.
Thus, methods for efficient extraction of technetium frommolybdenum must be studied, and the usability of thetechnetium extracted as a tracer must be confirmed.
EXPERIMENTS: Technetium-99m was determined tobe obtained through the production and subsequent decayof its parent nuclide, molybdenum-99, as a decay product.
Approximately 50 mg of natural molybdenum metal foil
(0.05 mm in thickness) was used for the production ofmolybdenum-99. The foil was irradiated in a Pn-2 radiation tube of the Kyoto University Research Reactor for
240 minutes at an output of 1 MW. Upon cooling for
approximately 2 hours after irradiation, the foil sample
was heated and dissolved in 7 N nitric acid and aqueoushydrogen peroxide. The solution was left to cool, followed by adsorption to an Empore filter [1,2] (made by
Sumitomo 3M Ltd.), and finally elution from the filter byvarying the nitric acid concentration from 1 N to 8 N.
The eluent was subjected to gamma-ray analysis at 739
keV emitted from molybdenum-99 and at 142.7 keVemitted from technetium-99m with a well-type HP-Ge
detector to determine the filter adsorption and elution
characteristics. The same chemical process was employed

採択課題番号 24075

respectively for the anion-exchanged resin, activatedalumina, and TEVA resin [3,4] as adsorbents for acolumn volume of 2 ml. Filter adsorption and elution
characteristics for these were also determined.
SUMMARY: To date, the irradiation was performed
on four times, and the chemical separation on six timesexperiments. Although the results are preliminary, theexperimental conditions enabled the production of therequisite amount of radioactivity for a tracer. Experimentation work will continue in 2013 for chemical separationin order to improve reproducibility and to determine theoptimum separation conditions. Furthermore, comparisonof the AnaLig Tc-02 method [5] with TEVA resin for Tc
separation. Based on the current data, chemical separation employing the TEVA resin and anion-exchanged
resin yielded better results for separation and recovery
rates, in comparison to the activated alumina and Empore
filter. The obtained technetium-99m as a tracer is planned
for use in determining technetium-99 recovery yield fromrespective samples of tap water, sea water, soil, and sea
weed. Quantitative analysis of the separated and collected
technetium-99 is planning to use the liquid scintillation
counter and ICP-MS.
REFERENCES:[1] S. C. Goheen, editor DOE Methods foe Evaluating
Environmental and Waste Management Samples.
[2] Battelle Press, Columbus, OH(1997). Method RS551,
Rapid isolation and measurement of technetium-99 using
3M EmporeTM Techetium Rad Disks.
[3] Horwitz, E.P., Dietz, M.L., Chiarizia, R., Diamond,H., Maxwell III, S.L., and Nelson, M., Analytica Chimica
Acta, 310(1995)63-78.
[4] Xialin Hou, M. Jensen, S. P. Nielsen, Applied Radiation and Isotopes, 65(2007)610-618.
[5] V. Pauova, V. Drabova, J.Strisovska, S.Balogh, J.
Radioanal. Nucl.Chem. 293(2012)309-312.

テクネチウム定量用トレーサの製造および化学分離法の検討	 (日大・文理)	  小林貴之	 
（京大・原子炉）関本俊、柴田誠一	 

共同通常	 

Adsorptivity of Polyvinylpolypyrrolidone
Irradiated by γ-Ray in HNO3 to Metal Ions in HCl

N. Miyata, K. Shunto, M. Nogami and N. Sato1
Faculty of Science and Engineering, Kinki University
1Research Reactor Institute, Kyoto University
INTRODUCTION: It has been revealed that polyvinylpolypyrrolidone (PVPP) changes the chemical structure by γ-ray irradiation in HNO3, where PVPP undergoes
the cleavage of the pyrrolidone ring by the addition ofoxygen atom originating from HNO3, followed by theformation of chain compounds by the successive additionof oxygen, leading to the generation of a primary-aminetype weakly-basic anion exchange resin and oxalic acid,(see Fig. 1). It has also been found that the functionalgroup (a) in Fig. 1 has uncommon chemical structureswith multiple coordinative sites and is relatively stable
under irradiation[1]. This means that it may be used asa novel type of chelating resin, particularly in acidic media originated from the multiple C=O groups in thestructure. So far, adsorptivities of the irradiated PVPP
to major metal ions in HNO3 media have been examined.
As the results, it was found that many kind of metal ionsare adsorbed from HNO3 of lower concentration range,
and that those such Zr(IV), Mo(VI), and Pd(II) are adsorbed also from HNO3 of higher concentration range[2].
In the present study, adsorptivities of the irradiated PVPP
were examined in HCl solutions, and compared withthose for HNO3 system.
NO

N
COOH

OH

NO

H

HO

PVPP

COOH

NHN

O
HOOC

H

O

O

NH

NH2

HOO

COOH

(a)

EXPERIMENTS: Similarly to the earlier work[2],
PVPP (Sigma-Aldrich) and HNO3 (6 mol/dm3 (= M))
were mixed in a Pyrex sample tube, and the mixture wasirradiated by the 60Co source at maximum 10 kGy/h up to2.3 MGy at room temperature under ambient atmosphere.
Adsorptivities of the irradiated PVPP to various metal
ions at equilibrium were examined by the batch method.
Samples of the conditioned adsorbent (wet 0.25 g) and 5
cm3 of 0.1 - 3 M HCl solutions containing a metal ion (10mM each) were shaken at 298K in a thermostatic shaking
bath for 24 h. Adsorptivities were evaluated by the distribution ratio, Kd, defined as,
C0 - CCxVW(cm3/g)

RESULTS: Kd values were found to basically increasewith increasing dose for many examined metal ions,which was similar to that for HNO3 system. Kd values
for various metal ions as a function of HCl concentration
for PVPP irradiated at 1.3 MGy are shown in Fig. 2. It
can be seen that Zr(IV) and Mo(VI) have high adsorptivities under all examined HCl concentrations. In particular, the Kd value for Zr(IV) in 0.1 M HCl is large. Pd(II),Fe(III) and Re(VII) also show relatively large Kd values.
On the other hand, adsorption of Nd(III) is found to beweak.
For both HCl and HNO3 systems, Kd values for eachacid concentration were found to have similar tendency,
except smaller Kd values for Mo(VI) in HCl systemcompared with HNO3. Such a similarity is of great interest, because the dominant chemical species of eachmetal ion including valences differ depending on concentration of HCl and HNO3. Considering the extraction
behavior and adsorptivity of conventional extractants andanion exchange resins in HCl and HNO3 systems, respectively, different sites of the functional group may participate in the adsorption. Namely, the contribution of oxygen atoms is greater for HNO3 system, while that of thenitrogen atom takes the more important role for HCl system. Further investigations are necessary for understanding the adsorption mechanisms.
105

(1)

Zr(IV)
Fe(III)

104

COOH

Fig. 1. Expected major route of change in chemical
structure of PVPP by γ-ray irradiation in HNO3.

Kd =where C0 and C denote the concentrations of the nuclide
in the solution before and after contact with the adsorbent,respectively. V and W represent the volume of the solution and the weight of the dry adsorbent, respectively.

Kd / cm3/g

CO9-2Mo(VI)
Re(VII)

Pd(II)
Nd(III)103
1021011000123[HCl] / M

Fig. 2. Adsorptivity of PVPP irradiated in 6M HNO3 at
1.3 MGy to various metal ions in HCl.
REFERENCES:[1] M. Nogami et al., J. Radioanal. Nucl. Chem., 296(2013) 423-427.
[2] N. Miyata et al., KURRI Progress Report 2010 (2011)258.

採択課題番号 24091 アクチニルイオン配位性アミド化合物の耐ガンマ線性に関する研究 共同通常（近大・理工）宮田直也、春藤圭志、野上雅伸、（京大・原子炉）佐藤信浩