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The correlation of the isotopic composition of uranium, plutonium, neodymium, and cesium with the burnup for high burnup pressurized water reactor fuels irradiated in nuclear power reactors has been experimentally investigated. The total burnup was determined by Nd-148 and the fractional 235U burnup was determined by U and Pu mass spectrometric methods. The isotopic compositions of U, Pu, Nd, and Cs after their separation from the irradiated fuel samples were measured using thermal ionization mass spectrometry. The contents of these elements in the irradiated fuel were determined through an isotope dilution mass spectrometric method using 233U, 242Pu, 150Nd, and 133Cs as spikes. The activity ratios of Cs isotopes in the fuel samples were determined using gamma-ray spectrometry. The content of each element and its isotopic compositions in the irradiated fuel were expressed by their correlation with the total and fractional burnup, burnup parameters, and the isotopic compositions of different elements. The results obtained from the experimental methods were compared with those calculated using the ORIGEN-S code.

AbstractThe oxidation behavior of iodide ion (I−) was investigated in aqueous solutions under a high dose rate of gamma irradiation in the range of 0 to 10 kGy·h−1. In particular, we investigated the formation of tri-iodide ion (I3−), the pH change of the solution, and the behavior of iodine species after the irradiation. As the gamma dose and the irradiation time increased, both the formation rate and the amount of I3−correspondingly increased. While I3−is not present above pH 10 due to its disproportionation reaction even without gamma irradiation, with irradiation, I3−does not exist above pH 6.4 because the H2O2acts as a reductant above pH 5.4. At relatively high concentrations of I−, I3−was the major oxidation species of the gamma irradiation. However, as the irradiation progressed, the concentration of I3−decreased gradually, and eventually, I2was left as the only species.

A determination method for 237Np in spent nuclear fuel samples was developed using an isotope dilution method with 239Np as a spike. In this method, inductively coupled plasma mass spectrometry (ICP-MS) was taken for the 237Np instead of the previously used alpha spectrometry. 237Np and 239Np were measured by ICP-MS and gamma spectrometry, respectively. The recovery yield of 237Np in synthetic samples was 95.9±9.7% (1S, n=4). The 237Np contents in the spent fuel samples were 0.15, 0.25, and 1.06 μg/mgU and these values were compared with those from ORIGEN-2 code. A fairly good agreement between the measurements (m) and calculations (c) was obtained, giving ratios (m/c) of 0.93, 1.12 and 1.25 for the three PWR spent fuel samples with burnups of 16.7, 19.0, and 55.9 GWd/MtU, respectively.

Among the radioactive wastes generated from the nuclear power plant, a radioactive nuclide such as 129I is classified as a difficult-to-measure (DTM) nuclide, owing to its low specific activity. Therefore, the establishment of an analytical procedure, including a chemical separation for 129I as a representative DTM, becomes essential.

AbstractThe dispersion properties of boron carbide (B4C) microparticles in aqueous media were investigated by measuring the particle size distribution, the dispersibility, and the zeta potential as these properties relate to their application as neutron absorbers in fuel-storage pool water. The B4C powder is composed of particles with a narrow size distribution, with a d50(mean diameter) of 0.65 μm. The amount of B4C particles dispersed decreased exponentially with increasing dispersion time. The dispersibility of B4C particles increased with an increase in the loading of B4C particles and reached a maximum value at 12.91 wt%. The zeta potential of the B4C suspension was measured as a function of pH and temperature. The B4C suspension has a negative zeta potential value in the pH range between 2 and 12. The dispersion of B4C particles was not greatly influenced by the addition of boric acid (H3BO3). The absolute value of the zeta potential decreased with increasing temperature.

To improve the long-term performance of Ag/AgCl electrodes, which are commonly used as reference electrodes, a correction technique was developed that involves monitoring the dilution of the internal electrolyte. The dilution of the internal electrolyte was estimated using the UV/VIS absorbance of the electrolyte to which a spectrally active material (a triphenylmethane dye; TPMe) had been added. With this technique, the long-term performance of the Ag/AgCl electrode was investigated when the electrode was exposed to NaHCO3 solutions with various concentrations. We investigated effects of KCl and NaHCO3 on the UV/VIS absorbance of TPMe and the effects of TPMe and NaHCO3 on the potential of the Ag/AgCl electrode. Based on the experimental results, this technique was estimated to be applicable to the correction of the potential of Ag/AgCl electrodes as long as the KCl concentration of the internal electrolyte is maintained between 0.01 and 0.1 M. In NaHCO3 solutions, the correction technique was found to have another limitation determined by the contamination ratio defined as [NaHCO3]/[KCl].

The infrared spectra of uranium oxides (UOx) of various O/U ratios (x = 2–2:667 in UOx) were measured by using ATR-FTIR in order to investigate the applicability of ATR technology to the characterization of uranium oxides or nuclear fuel. The samples of uranium oxides (UOx) were prepared by heating UO2powder in air atmosphere followed by weighing to determine the gains by oxygen. X-ray diffraction (XRD) patterns for the same samples of infrared spectra were measured to get information on their phases on uranium oxides (UOx) with increasing x. The measured characteristic bands from UOxsamples could be assigned well by referring to the spectra reported in the literature and comparing with the diffraction patterns measured. The relationship between absorbance and O/U ratio (x) was determined. We discussed about using it for the O/U ratio estimation of uranium oxides of unknown composition. It was confirmed that ATR technology for infrared spectroscopy can be useful for the studies of radioactive materials that are difficult to handle using conventional methods.

AbstractThis work studied a conceptual process to recover uranium alone from spent nuclear fuel using high-alkaline carbonate media with hydrogen peroxide for the purposes of reducing the volume of high-level active waste and recycling of uranium from the spent fuel with greatly enhanced proliferation resistance, environmental friendliness, and operational safety. The transuranium (TRU) elements were evaluated to be undissolved and precipitated together with other fission products during the oxidative leaching of uranium from the spent fuel. The leaching ratio of uranium dioxide to TRU dioxide from spent fuel in the carbonate solution with H2O2was estimated to be more than about 108. Only Cs, Tc, Mo, and Te among the major fission products in the spent fuel were dissolved together in the carbonate solution. In the carbonate solution with H2O2, UO2was dissolved in the form of uranyl peroxo-carbonato complex ions, which could be recovered in the form of uranium peroxide precipitate with a very low solubility by acidification of the solution in a succeeding step. All the inorganic salts of Na2CO3, NaOH, and HNO3used in the process suggested could be almost completely recovered and recycled into the process again without any generation of secondary wastes.

The line-broadening mechanism for three emission lines (510.55, 515.32, and 521.82 nm) in laser-induced copper plasma was investigated by time-resolved laser-induced breakdown spectroscopy. Two emission lines observed at 515.32 and 521.82 nm revealed a dramatic decrease in linewidth as the delay of the gate was increased, while the line at 510.55 nm showed a small decrease in linewidth. The different line-broadening behavior of the three transition lines is attributed to both Stark broadening and Rydberg-like atomic property at the energy levels involved in the emission process. The effect of the size of buffer gas as well as the intensity of laser on line broadening for these three lines is identified as minimal.

Resonance ionization mass spectrometry (RIMS) been applied for the investigation of states of the samarium atom. The 1-color and 2-color RIMS have been used obtain optimal photoionization schemes and to determine the Sm content of standard solutions. For 1-color 3-photon ionization schemes maximum intensity of ion signal is observed at 577.86 nm. When 2-color 3-photon ionization is adopted for the ion detection, however, a level located at 17 831 cm⁻¹( ⁷F₃) from the ⁷F₂ state (812 cm⁻¹) is regarded as the most efficient first excited state for ionization. Among the 2-color schemes using a level 17 831 cm⁻¹ as the first excited state, a level located at 34 460.4 cm⁻¹ is regarded as the efficient excited state for the detection sensitivity. Based on this optimal scheme determination of Sm contents in concentrations of standard solutions is performed. The minimum amount of Sm which can be detected by 2-color photoionization scheme {4f⁶6s^{2 7}F₂ (812 cm⁻¹)→4f⁶6s6p⁷F₃° (17 831 cm⁻¹)→34 460.4 cm⁻¹ →continuum} is estimated as 200 fg.

Abstract: The detection of radiocesium in microparticles was performed by using an ion trap mass spectrometer coupled with laser desorption and ionization. Pulsed laser desorbed particle and the resulted ions were analyzed by an ion trap mass analyzer. The presence of radiocesium, especially about137Cs, in microparticles was verified by single as well as successive particle analysis. The detection limit was reached to ≈ag/particle level with a signal-to-background ratio of 4. The inhomogeneous distribution of particle size and the irregular shapes of particle limit the quantitative evaluation of137Cs concentration in the microparticle. But this high sensitivity allows to monitor directly the radiocesium from small amounts of a microparticle sample.

A laser desorption/ionization ion trap mass spectrometer was developed and used for the identification of polycyclic aromatic hydrocarbons (PAHs) and pesticides, DDT and BHC, condensed on a single microparticle. The excimer (XeCl, 308 nm) laser was adopted for the desorption and ionization of the material from the particle surface and the resulting ions were analyzed with an ion trap mass spectrometer. The mass spectra obtained from laser desorption/ionization were similar to the results from electron impact ionization. Detection sensitivity was reached to sub-nanogram/particle order when a 5 mJ/pulse of energy of the laser was used. Tandem mass spectrometry was applied to the characterization of DDT by way of collision-induced dissociation of the parent ion with ambient He buffer gas.

Laser-induced copper plasma emission was investigated by time-integrated spatially resolved spectrometry. The comparative work on the plasma emission characteristics—specifically, self-absorption, line broadening, emission intensity, and metal ion formation—was carried out by the use of two different laser systems (XeCl excimer: = 308 nm; Nd:YAG: = 1064 and 532 nm). The characteristics of plasma emission produced by different wavelength radiation on copper atomic and ion lines under various atmospheric gases (argon, neon, and helium) and pressures (760–10 Torr) are presented. The differences in self-absorption and line broadening phenomena in the plasma location were explained by shock wave-driven excitation mechanism for atoms in the outer region in the plasma. The excitation temperatures of the plasma induced by 308- or 532-nm irradiation were also much higher that those induced by 1064-nm irradiation.

Excited states and autoionization states of the erbium atom were investigated by the use of multicolor resonance ionization mass spectrometry. Among the observed first excited states, a level [4f12(3H6)6s6p(3P1)] located 17,348 cm−1from the ground state is regarded as the most efficient state for excitation within the wavelength range investigated (560–600 nm), while a level located 17,080 cm−1from this first excited state (E= 34,458 cm−1) is identified as the best second excited state for the optimal photoionization scheme. Many ionization schemes adopting an autoionization state are also investigated, and the most efficient scheme is identified as 4f126s2(3H6) → 4f12(3H6)6s6p(3P10), 17,348 cm−1→ 34,458 cm−1→ continuum state, which corresponds to the two-color (ω1+ ω2+ ω1,2) scheme. Various concentrations of standard solutions for erbium are determined and the minimum amount detectable by two-color three-photon ionization was determined to be 20 pg.

INTRODUCTIONWhen a high-powered laser beam is focused onto a small area or spot of a solid surface, the temperature of the locally heated region rises rapidly to the vaporization temperature of the solid material and an optically induced plasma, frequently called a laser-induced plasma (LIP) or laser-ablated plasma (LAP) or laser spark is formed at the surface. The plasma will be formed when the laser power density exceeds the breakdown threshold value of the solid surface. Although different materials have different breakdown thresholds, an optical plasma is produced when the laser power density exceeds several megawatts per centimeter squared (106- 109W/cm2). This plasma has been used for sampling, atomization, excitation, and ionization in analyhcal atomic spectroscopy. It has also been frequently used and proposed as a source for atomic emission spectrometry (AES). In this case the technique is most ofien referred to as laser microprobe optical emission spectrometry (LM-OES) developed by Brech and Cross [1] in early nineteen-sixties or more recently called laser-induced breakdown spectrometry (LIBS) [2,3]. Generally, this analyhcal technique involves two steps; the pulsed focused laser beam directed into a gaseous sample or the surface of a solid or liquid, to produce a transient LIP, followed by the measurement of a characteristic atomic emission signal related to some species present in the plasma. The LIP formed is tightly focused and consists of vaporized atoms, ions, electrons, and molecular fragments. The application of LIBS for direct spectrochemical analysis is a rapidly growing field ranging from the detection of atmospheric pollutants to monitoring of material production processes, and even to “clean-room” technology. Laser ablation techniques have also been applied for solid sample introduction into other plasma sources [4–9]. In recent years, the powerful technique of LIBS as an analytical tool has been recognized by a number of research groups, and has led to an increasing number of publications on the applications of LIBS both in the laboratory and in industry. This growing success of LIBS is a result of thorough research carried out to understand the related plasma physical processes, aided by marked improvements in laser systems and photodetector technology.

AbstractThe excitation temperatures of sputtered gadolinium and uranium atoms in an argon hollow cathode discharge have been determined by diode laser-excited optogalvanic spectroscopy. These results have been compared to those determined by conventional emission spectroscopy. It was found that the temperatures derived from each method do not differ very much, but the optogalvanic method revealed a better standard deviation uncertainty due to the good signal-to-background ratios and excellent spectral resolutions. Temperature variations with discharge currents ranging from 15 to 50 mA have been examined.

Synthesis of with or was investigated in a LiCl-KCl eutectic melt at by using cyclic voltammetry (CV) and ultraviolet-visible (UV-vis) spectroscopy. CV results showed that the equilibrium potentials of the species are larger in sequence of . UV-vis spectroscopy results exhibited that was directly produced in the eutectic melt containing . In , U metal was oxidized to by , and then was reduced to by additional U. From these results, the reaction mechanisms taking place during the synthesis are proposed.

Gamma spectra of general and explosive materials were obtained by using the developed neutron induced prompt gamma-ray spectrometry system containing a neutron generator, where the neutron source was created from a deuterium-deuterium reaction, and they were examined to establish whether the samples were explosives or not by using the pattern recognition method. When the gamma spectra of real explosives (or general materials) were projected into the already prepared training set for the pattern recognition, they were placed in the categories of explosives (or general materials) properly.

To improve the long-term performance of Ag/AgCl electrodes, which are commonly used as reference electrodes, a correction technique was developed that involves monitoring the dilution of the internal electrolyte. The dilution of the internal electrolyte was estimated using the UV/VIS absorbance of the electrolyte to which a spectrally active material (a triphenylmethane dye; TPMe) had been added. With this technique, the long-term performance of the Ag/AgCl electrode was investigated when the electrode was exposed to NaHCO3solutions with various concentrations. We investigated effects of KCl and NaHCO3on the UV/VIS absorbance of TPMe and the effects of TPMe and NaHCO3on the potential of the Ag/AgCl electrode. Based on the experimental results, this technique was estimated to be applicable to the correction of the potential of Ag/AgCl electrodes as long as the KCl concentration of the internal electrolyte is maintained between 0.01 and 0.1 M. In NaHCO3solutions, the correction technique was found to have another limitation determined by the contamination ratio defined as [NaHCO3]/[KCl].

Synthesis of U3+with Cd2+or Bi3+was investigated in a LiCl–KCl eutectic melt at 500°Cby using cyclic voltammetry (CV) and ultraviolet-visible (UV-vis) spectroscopy. CV results showed that the equilibrium potentials of the species are larger in sequence of U0/3+