CO9-1

Stability of Silica-supported Monoamide Resins
with Selectivity to U(IV) and U(VI) Against γ-ray Irradiation in HNO3D. Mori, M. Nogami and N. Sato1
Faculty of Science and Engineering, Kinki University
Research Reactor Institute, Kyoto University

1INTRODUCTION: In order to develop resins with selectivity to U(VI) in HNO3 media, we have synthesized
several silica-supported polymer beads with the structureof a monoamide as the functional group. The examinationon their adsorptivities to various metal ions has clarified
that among these resins those consisting of N,N-dimethylacrylamide (Silica-DMAA) and N-methyl-N-vinylbenzylacetamide (Silica-MVBAA) have selectivity to U(VI)and U(IV), respectively, where major fission product (FP)ions are found to show no or very little adsorption fromHNO3 ranging up to 6 mol/dm3 (= M) [1, 2]. For wider
applications of these resins including treatment of highlyradioactive solutions, it is necessary to investigate theirstability under irradiation conditions. In this study, theabove two resins were irradiated by γ-ray in HNO3 andadsorptivities to FP ions were examined. The structurechange in the resins by irradiation was also studied.
EXPERIMENTS: Silica-DMAA and MVBAA resins
were synthesized in a similar manner as previously reported[1, 3]. The resins and HNO3 of up to 6 M weremixed in a Pyrex sample tube at a ratio of 5 cm3/g, respectively, and used as the samples for γ-ray irradiation.
Irradiation by the 60Co source was performed at max.
16.3 kGy/h up to 1.6 MGy at room temperature underambient atmosphere. The irradiated resins were separatedfrom the supernatant and washed using distilled water toavoid further degradation of the resins by HNO3. The
resulting resins and the supernatants were analyzed by IRand 1H NMR (400 MHz, solvent : D2O), respectively.
Adsorptivities of the irradiated resins to FP ions wereexamined by the batch method similar to the previous
studies[1-3]. Samples of the conditioned resins irradiatedin 3 or 6 M HNO3 were mixed with 0.01 - 6 M HNO3
solutions containing 10 mM FP ions at a ratio of wet 0.05
g/cm3, respectively, and shaken at 298 K in a thermostatic
shaking bath for 1 h. After shaking, samples of the supernatant were taken and the concentrations of FPs weremeasured using ICP-AES or ICP-MS. Adsorptivities
were evaluated by the distribution ratio, Kd, defined as,C0 - CV(1)
Kd =x(cm3/g)
CW
where C0 and C denote the concentrations of the FP ionsin the solution before and after contact with the resin,respectively. V and W represent the volume of the solution and the weight of the dry resin, respectively.
RESULTS: For the IR analyses, a new peak generated
at around 1700 cm-1 for DMAA irradiated in HNO3 ofhigher concentration. While, no clear changes in thespectra were observed in the irradiated MVBAA. 1H
NMR spectra of the supernatants after irradiation showed
exclusively distinguished peaks which would be attributed to N,N-dimethylamine (ca. 2.7 ppm (vs. DSS),CH3, singlet) for DMAA irradiated in 6 M HNO3 at 1.6
MGy and acetic acid (ca. 2.1 ppm (ditto), CH3, singlet)for MVBAA irradiated in 6 M HNO3 at 0.90 MGy, respectively.
Based on the above results, it would be proposed thatboth two resins were mainly degraded simply by thebreak of each amide bond, followed by the formation ofpolyacrylic acid from DMAA and secondary-amine-type
weakly-basic anion exchange resin from MVBAA, respectively (see Fig.1). These degradation properties aresimilar to those of chain-type monoamide extractants[4].
Considering the degradation properties of these monoamide compounds, the two resins are expected to be stable against irradiation in HNO3 of lower concentrationsuch as 0.1 M.
(a)

C=O
N – CH3
CH3DMAA

C=O+

CH3H–NCH3OH

polyacrylic acidN,N-dimethylamine(b)+CH2CH2N – CH3

N – CH3

C=OCH3MVBAAO
CH3 - COHH

secondary-amine-type
weakly-basic anion
exchange resin

acetic acidFig. 1. Expected major degradation routes of monoamide
resins by γ-ray irradiation in HNO3; (a) Silica-DMAA, (b) Silica-MVBAA.
The irradiated resins showed weak adsorptions forZr(IV) and Pd(II) from HNO3 of lower concentration
ranges and no or little adsorptions were found for otherFP ions, which was in accordance with the expected adsorptivities of the degraded resins. Besides, it is expectedthat the two irradiated resins keep the selectivity to U
species, respectively, in HNO3 of ca. 3 M and higher.
REFERENCES:[1] M. Nogami et al., J. Radioanal. Nucl. Chem. 273(2007) 37.
[2] M. Nogami et al., J. Radioanal. Nucl. Chem. 284(2010) 195.
[3] M. Nogami et al., Prog. Nucl. Energy, 284 (2008) 462.
[4] P B Ruikar et al., J. Radioanal. Nucl. Chem. Letters
176 (1993) 103.

採択課題番号 23040 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（近大・理工）森大祐、野上雅伸（京大原子炉）佐藤信浩

共同通常CO9-2

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
1
Research Reactor Institute, Kyoto University
INTRODUCTION: 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 fission
products, 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 neutronirradiation. The handling of molybdenum metal is easy,
but the generated specific radioactivity is low. Thus,
methods for efficient extraction of technetium from molybdenum must be studied, and the usability of the technetium 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 the Pn-2 radiation tube of the Kyoto University Research Reactor for
50 minutes at 5 MW. Upon cooling for approximately 2hours after irradiation, the foil sample was heated anddissolved in 7 N nitric acid and aqueous hydrogen peroxide. The solution was left to cool, followed by adsorption to an Empore filter[1, 2] (made by 3M Ltd.), andfinally elution from the filter by varying the nitric acidconcentration from 1 N to 8 N. The eluent was subjectedto gamma-ray analysis at 739 keV emitted from molybdenum-99 and at 142.7 keV emitted from technetium-99m with a well-type HP-Ge detector to determine
the filter adsorption and elution characteristics. The samechemical process was employed respectively for the ani-

on-exchanged resin, activated alumina, and TEVA resin[3] as adsorbents for a column volume of 2 ml. Filter
adsorption and elution characteristics for these were alsodetermined.
SUMMARY: This experiment was adopted in the second
half of fiscal 2011. To date, the irradiation was performedon twice, and the chemical separation on four times experiments. Although the results are preliminary, the experimental conditions enabled the production of the requisite amount of radioactivity for a tracer. Experimentation work will continue in 2012 for chemical separationin order to improve reproducibility and to determine theoptimum separation conditions. 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 atracer is planned for use in determining technetium-99
recovery yield from respective samples of tap water, seawater, soil, and sea weed. Quantitative analysis of theseparated and collected technetium-99 is planning to use
the liquid scintillation counter and ICP-MS.
References:[1] S. C. Goheen, editor, DOE Methods for Evaluating
Environmental and Waste Management Samples.
[2] Battelle Press, Columbus, OH (1997). Method RS551,
Rapid isolation and measurement of technetium-99
using 3M Empore™ Technetium 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.

採択課題番号 23076 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

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