[en] Highlights: • Direct-patterning of SnO₂ films incorporated with Pt nanoparticles. • Pt incorporated SnO₂ thin films by using photochemical solution deposition. • Reduction catalytic behavior of Pt nanoparticles. • Progress reduction of SnO₂ with increasing amount of Pt nanoparticles. • Enhanced electrical conductivity of SnO₂ films with Pt nanoparticles incorporation. - Abstract: Direct-patterning of SnO₂ films incorporating Pt nanoparticles was performed by using a photochemical solution deposition without a photoresist or dry etching. Incorporating Pt nanoparticles into these films had a slight effect on their crystallinity and almost no effect on their transmittance. The inclusion of Pt nanoparticles enhanced the electrical conductivity of the SnO₂ thin films compared to their pristine forms. The chemical bonding state of the films was analyzed by X-ray photoelectron spectroscopy to investigate the effect of the Pt nanoparticles on the carrier concentration in the film. It was concluded that the reduction of SnO₂ thin films by Pt nanoparticles progressed as a result of the presence of the Pt nanoparticles, causing an oxygen deficiency to develop in SnO₂ and thereby influencing the carrier concentration of the film

[en] In this study, we discussed the limitations of gross alpha measurements for the characterization of radioactive wastes produced in nuclear facilities through experimental tests and Monte Carlo N-particle transport simulations. The determination of gross alpha is essential for the disposal of radioactive waste produced in nuclear facilities in Korea. The measurements of gross alpha are easy to perform and yield rapid analytical results, but it cannot be used for quantitative analysis. The error of counting efficiency for gross alpha with various masses of the deposit on planchets using KCl and ²⁴¹Am was determined. The relative deviation of the counting efficiency in samples having the same mass was 20%. Uranium was extracted from the soil through acid leaching and extraction chromatography, and the concentration of U determined by inductively coupled plasma–mass spectrometry (ICP-MS) was compared with the results for gross alpha. The gross alpha was underestimated by 50% compared to the U concentration by ICP-MS. The counting efficiency depended on the energy from the alpha emitters, which differed by up to three times in determination of the counting efficiency depending on the kinds of alpha radionuclides of interest. Therefore, the gross alpha is not compatible with the sum of radioactivity for each alpha emitter and is suitable as a screening method

[en] According to the Nuclear Safety Act, the part operating the nuclear facility have to characterize its radioactive waste, for example ³H, ¹⁴C, ⁵⁵Fe, ⁹⁰Sr, ⁹⁹Tc, ¹²⁹I, gamma isotopes and gross alpha. The fast and reliable analytical technique is a big issue in the characterization of radioactive waste, because the waste handling cost depends on its analytical results. The sequential determination of several radionuclides from one sample could be the economic alternative in processing wastes. Except the volatile radionuclides, such as ³H and ¹⁴C and gamma emitters, alpha and beta emitters should be chemically separated from the sample. This study presented the sequential separation of ⁹⁰Sr and ⁹⁹Tc from soil and concrete sample based on extraction chromatography. We collected soil and concrete samples produced from decommissioning of research reactor in Seoul. We analyzed the level of ⁹⁰Sr and ⁹⁹Tc in soil and concrete samples. The acid digestion was employed for the pretreatment and TEVA resin/Sr resin was used for chemical separation. The recovery of each radionuclide was estimated by determining stable Sr by ICP-OES and 99mTc by HPGe. ⁹⁹Tc and ⁹⁰Sr were determined by ICP-MS and LSC, respectively. Based on the performance test using the method standard sample, this method shows the reliable result, having from -8 to 2 % of relative error. The level of ⁹⁹Tc and ⁹⁰Sr in real soil and concrete samples were less than MDA.

[en] Environmental Radiation Monitoring was carried out with measurement of environment. Radiation and environmental radioactivity analysis on the sites of KAERI nuclear facilities and Seoul Research Reactors and their environments. The average level of environmental radiation dose measured by an ERM and the accumulated radiation dose by a TLD were almost same level compared with the previous years. The activity of gross alpha and gross beta, Tritium, Uranium and Strontium in environmental samples showed a environmental level. The radioactivities of most γ-radionuclides in air particulate, fallout, rain water and ground water were less than MDA except 40K or 7Be which are natural radionuclides. However, not only 40K or 7Be but also 137Cs or 131I were detected in the surface soil, discharge sediment and surface water.

[en] An analytical procedure for detecting ²²⁶Ra in naturally occurring radioactive materials (NORMs) using a liquid scintillation counter (LSC) was developed and validated with reference materials (zircon matrix, bauxite matrix, coal fly ash, and phosphogypsum) that represent typical NORMs. The ²²⁶Ra was released from samples by a fusion method and was separated using sulfate-coprecipitation. Next, a ²²²Rn-emanation technique was applied for the determination of ²²⁶Ra. The counting efficiency was 238 ± 8% with glass vials. The recovery for the reference materials was 80 ± 11%. The linearity of the method was tested with different masses of zircon matrix reference materials. Using 15 types of real NORMs, including raw materials and by-products, this LSC method was compared with γ-spectrometry, which had already been validated for ²²⁶Ra analysis. The correlation coefficient for the results from the LSC method and γ-spectrometry was 0.993 ± 0.058. - Highlights: • We developed a method to detect ²²⁶Ra in naturally occurring radioactive materials. • A liquid scintillation counter (LSC) was validated with reference materials. • LSC is preferable to γ-spectrometry with respect to the background count rate. • LSC offers a better chemical separation than α-spectrometry.

[en] The analysis of ⁴¹Ca in concrete generated from the nuclear facilities decommissioning is critical for ensuring the safe management of radioactive waste. An analytical method for the determination of ⁴¹Ca in concrete is described. ⁴¹Ca is a neutron-activated long radionuclide, and hence, for accurate analysis, it is necessary to completely extract Ca from the concrete sample where it exists as the predominant element. The decomposition methods employed were the acid leaching, microwave digestion, and alkali fusion. A comparison of the results indicated that the alkali fusion is the most suitable way for the separation of Ca from the concrete sample. Several processes of hydroxide and carbonate precipitation were employed to separate ⁴¹Ca from interferences. The method relies on the differences in the solubility of the generated products. The behavior of Ca and the interfering elements such as Fe, Ni, Co, Eu, Ba, and Sr is examined at each separation step. The purified ⁴¹Ca was measured by a liquid scintillation counter, and the quench curve and counting efficiency were determined by using a certified reference material of known ⁴¹Ca activity. The recoveries in this study ranged from 56 to 68%, and the minimum detectable activity was 50 mBq g^-1 with 0.5 g of concrete sample

[en] Environmental Radiation Monitoring was carried out with measurement of environment. radiation and environmental radioactivity analysis on the sites of KAERI nuclear facilities and Seoul Research Reactors and their environments. The average level of environmental radiation dose measured by an ERM and the accumulated radiation dose by a TLD were almost same level compared with the previous years. The activity of gross alpha and gross beta, Tritium, Uranium and Strontium in environmental samples showed a environmental level. The radioactivities of most γ-radionuclides in air particulate, fallout, rain water and ground water were less than MDA except ⁴⁰K or ⁷B which are natural radionuclides. However, not only ⁴⁰K or ⁷B but also ¹³⁷Cs or ¹³¹I were detected in the surface soil, discharge sediment and surface water.

[en] In general, α-spectrometry has a prominent measurement capability at a very low activity level of ²³⁸U, ²³⁵U, and ²³⁴U, it has a major disadvantage of a long counting time (especially ²³⁵U) for the determination of α-nuclide activity. Contrary to the α-spectrometry method, a measurement technique using ICP-MS with an advanced sample introduction and mass counting system allows radioactivity in many samples to be measured within a short time period with a high degree of accuracy and precision. In order to satisfy the method detectable activity (MDA) for the regulation of a radioactivity monitoring program, the analysis of U isotopes always requires an extremely large sample amount. These procedures usually remove all of the organics in the samples during the dry ashing. The ashed residues have been especially complicated into a liquid phase because of their carbonization. This process is very time consuming and does not fully recover the target isotopes. Thus, a digestion method for ashed-residue was developed for a rapid analysis of U isotopes using LiBO₂ fusion and Fe co-precipitation. The liquid samples were directly vaporized and co-precipitated by Fe(OH)₃ for concentration of target nuclides.

[en] An analysis of solid matrix samples is especially complicated owing to a destruction of the matrix and digestion into a liquid phase. These procedures are usually very time consuming and do not fully recover target isotopes. For this reason, a rapid and accurate analytical method that can be used to evaluate the radioactivity of U isotopes should be developed and validated. In this study, in order to immediately response, the rapid digestion and purification procedure for U isotopes in environmental sample media such as soil and sediment were developed using LiBO₂ fusion and ICP-MS measurement. In order concentrate and purify the U isotopes, the rapid selective extraction chromatography process was developed and applied using automatic sample separation system. Finally, the evaluated method in this study were applied for quantitative determination of U isotopes of the sediments CRMs (Certified reference materials) samples. Typically, ICP-MS techniques have been well acknowledged to have extremely low detection limit with high resolution. And the technique could analyze the isotopic ratio analysis (e.g., Pu-239/240, U- 235/238/234). Based on the analytical results for rapid determination of U isotopic ratio, one may conclude that the evaluated method for actinides using alkali-fusion, extraction chromatography process, and ICP-MS measurements is fast and fairly reliable.

[en] This paper describes the results of the development of an automated radionuclide separator from a large seawater sample. It consists of two parts, which are a concentration part with a cation exchange resin (Dowex50Wx8, Sigma-Aldrich) and a purification part with Sr resin (Eichrom Technology). The volume of raw seawater sample was reduced by about 25% at the concentration part, and radiostrontium was purified at the Sr-resin part. The chemical yield ranged from 92% to 96%. This automated system can simultaneously execute four samples. Using liquid scintillation counting (LSC) and Cherenkov counting, the analysis of Sr-89/90 from seawater could be completed within 3 days. (author)