Kinds Of Radionuclides Research Articles

Combined use of tannic acid-type organic composite adsorbents and ozone for simultaneous removal of various kinds of radionuclides in river water

Tannic acid-type organic composite adsorbents (PA316TAS, AR-01TAS, PYRTAS, WA10TAS, WA20TAS, and WA30TAS), combined with hydrolyzed and sulfonated tannic acid (TAS) and porous-type strongly basic anion-exchange resin (PA316), benzimidazole-type anion-exchange resin embedded in high-porous silica beads (AR-01), pyridine-type anion-exchange resin (PYR), acrylic-type weakly basic anion-exchange resin (WA10), or styrene-type weakly basic anion-exchange resins (WA20 and WA30) for simultaneous removal of various kinds of radionuclides in river water were successfully synthesized. The adsorption behavior of twelve kinds of simulated radionuclides (Mn, Co, Sr, Y, Ru, Rh, Sb, Te, Cs, Ba, Eu, and I (I− and IO3−)) on these composite adsorbents has been studied in real river water at room temperature. PA316TAS adsorbents showed much higher distribution coefficients (Kd) for all metal ions. TAS structure has more selective adsorption ability for Mn, Co, Sr, Y, Cs, Ba, Eu, and IO3−. On the other hand, Y, Ru, Rh, Sb, Te, Eu, I (I− and IO3−) were adsorbed on both PA316 and TAS structures. To evaluate the validity of these mechanistic expectations, the respective chemical adsorption behaviors of Mn, Co, Sr, etc. and PA316TAS adsorbent were examined in river water ranging in temperature from 278 to 333 K. As was expected, one adsorption mechanism for Mn, Co, Sr, Cs, and Ba systems and two types of adsorption mechanisms for Y, Ru, Rh, Sb, Te, Eu, I (I− and IO3−) systems were observed. On the other hand, the precipitation of Mn, Co, Y, Ru, Rh, Te, and Eu was formed by ozonation for river water, that is, ozone can transform Mn, Co, Y, Ru, Rh, Te, and Eu ions into the insoluble precipitates. Hence, one straight line for Sr, Cs, Ba systems and two types of straight lines for Sb, I (I− and IO3−) systems were obtained in river water treated with ozone. The chromatography experiments of Cs, Sr, I (I− and IO3−) were carried out to calculate their maximum adsorption capacities. The obtained maximum adsorption capacities of Cs, Sr, and I− mixed with IO3− were 1.7 × 10−4 (Cs), 1.8 × 10−3 (Cs/O3), 7.8 × 10−5 (Sr), 5.6 × 10−4 (Sr/O3), 5.4 × 10−2 (I− and IO3−), 3.1 × 10−2 (I− and IO3−/O3) mol/g - PA316TAS. It was discovered that the maximum adsorption capacities of I− and IO3− for the composite adsorbent is unprecedented high and the capacity become much greater than an order of magnitude, compared with those of previous reports. This phenomenon suggests the formation of electron-donor-acceptor (EDA) complexes or pseudo EDA complex. Based on these results, it was concluded that the combined use of tannic acid-type organic composite adsorbents and ozone made it possible to remove simultaneously and effectively various kinds of radionuclides in river water in the wide pH and temperature ranges.

Adsorption of radionuclides on the monolayer MoS2

How to remove radionuclides from radioactive wastewater has long been a difficult problem, especially in nuclear accidents. In this paper, the adsorption of radionuclides Cs, Sr, and Ba on the monolayer MoS2 was investigated by using the first principles calculation method. Through the calculation of adsorption energy and Hirshfeld charge of the radionuclides on the monolayer MoS2 at six adsorption sites, the results show that all of the radionuclides chemisorbed on the monolayer MoS2, and the adsorption strength of these three kinds of radionuclides on the monolayer MoS2 is Ba > Sr > Cs. This work might shed some light on the treatment of the radioactive wastewater.

Tools for modeling radioactive contaminants in chip materials

Radioactive pollutants are naturally present in microelectronic device materials and can be an issue for the reliability of devices. The main concern is alpha emitters that produce high-energy particles (a few MeV) that ionize the semiconductor and then trigger soft errors. The question is to know what kinds of radionuclides are present in the device, their location in the device and the abundance of each species. In this paper we describe tools that are required to address the issue of radioactive pollutants in electronic devices.

Effect of environmental conditions on the sorption of radiocobalt on titanate/graphene oxide composites

The titanate/graphene oxide composites were successfully synthesized by thermal treatment and were characterized by using SEM, XRD and FTIR in detail. The as-synthesized titanate/graphene oxide composites were applied as a new adsorbent to remove radiocobalt (60Co) from aqueous solution as a function of ionic strength, pH, contact time, temperature and cation ions. The results indicated that the sorption of 60Co on titanate/graphene oxide composites was strongly dependent on pH and ionic strength. The thermodynamic parameters calculated from the temperature-dependent sorption isotherms indicated that the sorption was a spontaneous and endothermic process. The titanate/graphene oxide composites can be a promising material for the preconcentration of 60Co and other kinds of radionuclides from aqueous solutions in environmental pollution cleanup in possible application.

Expanded Applications of Liquid Scintillation Counting and Several Related Issues

Liquid scintillation counting (LSC) is widely used in the field of radiation measurements. Some main developments in the application of LSC in our laboratory have been introduced briefly in this paper. These developments include: the use of LSC alone to determine 152Eu and 241Am simultaneously instead of using the common γ spectrometry, and the use of LSC in combination with α or γ spectrometry in various cases. All these developments expand the applications of LSC, which can lead to significant increase in production of radioactive measurement work. In addition, we have discussions about several issues which are very important to LSC application, i.e. the quenching effect on α/β discrimination, the influences of anticoincidence shield on count rates for various kinds of radionuclides, the effect of statistical fluctuations in external standard spectrum on quench index parameter, and the long-term stability on basic performances of LSC cocktails.

Nuclear medical imaging using β +γ coincidences from 44Sc radio-nuclide with liquid xenon as detection medium

We report on a new nuclear medical imaging technique based on the measurement of the emitter location in the three dimensions with a few mm spatial resolution using β +γ emitters. Such measurement could be realized thanks to a new kind of radio-nuclides which emit a γ-ray quasi-simultaneously with the β + decay. The most interesting radio-nuclide candidate, namely 44Sc, will be potentially produced at the Nantes cyclotron ARRONAX. The principle is to reconstruct the intersection of the classical line of response (obtained with a standard PET camera) with the direction cone defined by the third γ-ray. The emission angle measurement of this additional γ-ray involves the use of a Compton telescope for which a new generation of camera based on a liquid xenon (LXe) time projection chamber is considered. GEANT3 simulations of a large acceptance LXe Compton telescope combined with a commercial micro-PET (LSO crystals) have been performed and the obtained results will be presented. They demonstrate that a good image can be obtained from the accumulation of each three-dimensional measured position. A spatial resolution of 2.3 mm has been reached with an injected activity of 0.5 MBq for a 44Sc point source emitter.

Model of Analysis of the Groundwater-Protection Level in Shallow Land Burial of Radioactive Waste

A mathematical model of transfer of radionuclides in the aeration zone has been considered. The analytical solution for this model in a generalized form suitable for practical application has been obtained. A procedure enabling one to determine the optimum size of the protection zone and in which the maximum concentration of radionuclides does not exceed the maximum permissible levels for a specific kind of radionuclides has been proposed.

Extension of the efficiency calibration of germanium detectors using the GESPECOR software

To avoid losses due to coincidence summing, the efficiency calibration of gamma-spectrometers is often carried out by means of radionuclides emitting only one photon during a single decay. Calibration with this kind of radionuclides has, however the disadvantage that the energy range of the gamma rays (46 keV< E<1115 keV) is limited. Coincidence-summing corrections can be calculated with the Monte Carlo program Germanium Spectrometry Correction for multi gamma radionuclides which emit photons with energies above this range. The efficiency curve as a function of energy can therefore be extended up to 2.7 MeV with uncertainties below 4%.

Recent advances in medical radionuclide production and future perspective of compact medical cyclotrons

In recent years, many radiopharmaceuticals bearing different kind of radionuclides have been largely used in diagnostic and therapeutic studies, especially of cancer. The basic principle of radiodiagnosis and raditherapy is ensuring as low as radiation dose absorption by patients. Sometimes, the radionuclides having very short half-lives, and very interesting decay characteristics are required for this purpose. The use of short-lived radionuclides necessitates their productions just at the application sites. This necessity has provoked the development of compact particle accelerators. Nowadays, the radionuclide applications in diagnostic and therapeutic nuclear medicine are continuously escalation, and future perspective of these applications will strongly be depended on two important factors as being 1) increasing the variety of cyclotron-produced radionuclides, 2) design of new radiopharmaceuticals having different and specific metabolic pathways in normal and cancer tissues. For improvement of the first factor, new nuclear reactions should eventually be examined using new target materials. In this context, the targeting chemistry will be an essential role in this field. As the second factor, improvement of new radiopharmaceuticals will strongly be dependent on the biofunctional researches of new chemical agents and development of their radiolabeling techniques. The radionuclide production has evidently become more and more easy by using the compact medical cyclotrons. For this reason, the application of different radionuclides will be able to have an important role in the future either for scientific and technical applications or medical diagnostic and therapeutic studies. As a consequence of this progress, the basic nuclear scientists, especially nuclear and radiopharmaceutical chemists will be seeking professionals in the next new century.

Fundamental Study on the Solidification of Radionuclides with Hydrous TiIV Oxide Modified with Either Si or Zr

AbstractThe potentiality of hydrous TiIV-Si oxide (TS) and hydrous TiIV-Zr oxide (TZ) for the selective sorption and immobilization of radioactive Co2+, Eu3+, Th4+ and UO22+ ions has been studied experimentally: The distribution coefficients and sorption capacity for these ions at various conditions in solutions, the structure and the composition of the exchangers in relevant ionic forms at high temperatures, and the leaching rates from the calcined exchangers into water and 0.01M HNO3 solution at room temperature. These results were discussed together with the results previously obtained for Cs+ and St2+, in order to evaluate the performance of TS and TZ as solidification media for radioactive liquid waste. TS takes up these cations more than TZ does in acidic solutions due to the higher acidity of the exchange site. In TZ, transition metal ions show high affinity despite the small distribution coefficients for representative metal ions. The dissolution of Co2+, Eu3+, and Th4+ is very slow from both calcined exchangers due to the crystallization of titanates of these cations. The leaching rates of Cs+, St2+ and UO22+ from calcined TS are much slower than those from TZ, indicating the formation of titanium silicate containing these cations. Based on these results, TS is considered to be superior to TZ in the sorption capacity and fixation capability of various kinds of radionuclides and is considered as a promising material for the solidification of radwaste.

Testing performance of the improved pinhole collimator and its application to small animals

Testing performance of the improved pinhole collimator of 1.5 mm aperture attached to the gamma camera was carried out with three kinds of radionuclides, 99mTc, 67Ga and 131I, using a hand-made phantom. The results obtained in this experiment were compared to those obtained with a human pinhole collimator of 4 mm aperture. Those were nearly understood by taking account of the effective aperture of a pinhole collimator for each effective photon energy. And all scintigrams obtained from rats with various scintigraphy showed high resolution images.

Position of sediments in transfer of radionuclides released into coastal sea to human beings.

A great portion of radionuclides released into coastal sea is adsorbed into marine sediments and the adsorbed radionuclides causes the radioactive contamination of marine organisms and then transferred to human beings who consume them. In order to make a quantitative evaluation of this route, the transfer of 9 kinds of radionuclides from sediments to benthic organisms such as algae, bivalve and worm was observed. Then it was compared with the radioactivity in these organisms from radioactively contaminated sea water (Concentration factor). It was observed that the influence of sea water was larger than that of sediments as it was 104 times larger for 54Mn, 103 times larger for 59Fe, 60Co, 95Zr-95Nb, 106Ru-106Rh and 144Ce-144Pr, 102 times larger for 65Zn and 10-102 times larger for 115mCd and 137Cs.Consequently, sea water can be considered as the main route and sediments as the secondary in the case of quantitative comparison of the effect on the accumulation of radionuclides by marine organisms and in the transfer of radionuclides to human beings.

Combining of radionuclides with constituent materials of marine algae.

The relations between the accumulation-elimination of radionuclides and the constituent materials of marine algae were studied to determine more precisely the mechanism of the radioactive contamination of marine organisms. This will increase the information about the behavior of radionuclides in marine organisms in relation to the environmental conditions (temperature, physico-chemical state of radioisotope, and so on) and the biological conditions (feeding habits, species, and so on). Eisenia contaminated by 137Cs and 106Ru-106Rh was fractionated by solvent extraction into 6 fractions. The largest portion of 137Cs was in the boiling water fraction; 106Ru-106Rh was most extracted by 24% KOH solution. Elution patterns by Sephadex G-100 gel-filtration of samples differed largely from each other, both among the 3 kinds of radionuclides and between the 2 species of the algae. Therefore, the accumulation of the radionuclides by the marine algae was proved to be not only due to a physical adsorption to the surface of the algae but also to the biological combining of the radionuclides with the constituents of the algae. Furthermore, it was found that radionuclides which combine with a few constituents of alga are not eliminated equally. This is considered to be useful for the physiological analysis of elimination curves.