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The content of plutonium isotopes in high burnup pressurized water reactor fuel samples was examined using both alpha spectrometry and mass spectrometry after anion exchange separation. The measured values were compared with results calculated by the ORIGEN-2 code. On average, the ratios (m/c) of the measured values (m) over the calculated values (c) were 1.22±0.16 for (238)Pu, 1.02±0.14 for (239)Pu, 1.08±0.06 for (240)Pu, 1.06±0.16 for (241)Pu, and 1.13±0.08 for (242)Pu. Using the Pu data obtained in this work, correlations were derived between the alpha activity ratios of (238)Pu/((239)Pu+(240)Pu), the alpha specific activities of Pu, and the atom % abundances of the Pu isotopes. Using these correlations, the atom % abundances of the plutonium isotopes in the target samples were calculated. These calculated results agreed within a range from 2 to 8% of the experimentally derived values according to the isotopes of plutonium., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Surface assisted laser desorption ionization mass spectrometry (SALDI-MS) has been recognized as one of the prominent techniques in mass analysis of small molecules as well as large nonvolatile molecules since it bears many advantages compared to matrix assisted laser desorption ionization mass spectrometry. The use of SALDI-MS has been increasing for small molecules analysis with the development of new substrates materials for ionization such as porous silicons and nanomaterials. While most of researches about SALDI-MS are focusing on the development of new substrate materials, not much of works has been done for the verification of ionization mechanism of SALDI-MS. In this article, we reviewed the characteristics of SALDI-MS such as desorption/ionization mechanisms, signal enhancement by inorganic matrix, and recent trends on the development of new efficient matrix substrates. Among the reviewed ionization mechanisms, the laser ablation followed by generation of laser-induced plasma and shock wave is suggested to be more plausible mechanism in the desorption and ionization process of SALDI-MS, while other mechanisms are also recognized to contributes to the desorption and ionization process. Recent development of efficient substrate materials for SALDI-MS by adopting nanoparticles, nanomaterials, metal organic frameworks, and their combination was also reviewed. [ABSTRACT FROM AUTHOR]

In a recent international exercise, 10 international nuclear forensics laboratories successfully performed radiochronometry on three low enriched uranium oxide samples, providing 12 analytical results using three different parent-daughter pairs serving as independent chronometers. The vast majority of the results were consistent with one another and consistent with the known processing history of the materials. In general, for these particular samples, mass spectrometry gave more accurate and more precise analytical results than decay counting measurements. In addition, the concordance of the 235U–231Pa and 234U–230Th chronometers confirmed the validity of the age dating assumptions, increasing confidence in the resulting conclusions. [ABSTRACT FROM AUTHOR]

Abstract: A new pre-concentration system was developed for a trace detection of VOCs by adopting a ceramic heater, a dc power supply, a three-way solenoid valve, a micro-diaphragm pump, and a programmable logic control system. The adopted ceramic heater was made by coating carbon powder onto the inner wall of a ceramic tube and by additional coating of silver paste both on the inside as well as outside of the rims of a ceramic tube to create electrical connection with dc power supply. Various adsorbing materials, such as charcoal powder, molecular sieve, and Tenax-TA, were packed inside the ceramic heater for pre-concentration of VOCs from a sample reservoir. The ceramic heaters were prepared to have a resistance ranging from 10 to 25Ω, and the heating time was optimized from 8 to 16s in order to maximize the thermal desorption of the adsorbed VOCs while avoiding any possible damage to the ceramic heater. The performance of the developed system was estimated by measuring the enhancement of ion signals for VOCs by using the pre-concentration system and the laser photoionization mass spectrometry. The signal enhancement was identified to be better than 40 when compared to the signals measured without the pre-concentration device. [Copyright &y& Elsevier]

Abstract: The enhancement of ion signals by the resonant laser ablation (RLA) process was investigated by using a 2-color RLA mass spectrometry for samples containing Pb and Ni. Two laser beams, a second harmonic of Nd:YAG laser (532nm) and a UV beam of frequency tunable dye laser, were used for either simultaneous ablation by directing both lasers to the target sample or laser ablation followed by a resonant ionization. In both cases, the resonant enhancement of the ion signal was observed, but the mass resolution was much better when two lasers contribute to the laser ablation process by arranging both beams hit the sample at the same position. The enhancement factor was more prominent when the laser power was kept at low. The maximum resonance enhancement was more than 160 times for the Pb case when compared to the non-resonant laser ablation. Several NIST standard reference materials were analyzed by adopting RLA. [Copyright &y& Elsevier]

Thermal ionization mass spectrometry (TIMS) with a continuous heating technique is known as an effective method for measuring the isotope ratio in trace amounts of uranium. In this study, the analytical performance of thermal ionization mass spectrometry with a continuous heating technique was investigated using a standard plutonium solution (SRM 947). The influence of the heating rate of the evaporation filament on the precision and accuracy of the isotope ratios was examined using a plutonium solution sample at the fg level. Changing the heating rate of the evaporation filament on samples ranging from 0.1 fg to 1000 fg revealed that the influence of the heating rate on the precision and accuracy of the isotope ratios was slight around the heating rate range of 100–250 mA/min. All of the isotope ratios of plutonium (SRM 947), 238 Pu/ 239 Pu, 240 Pu/ 239 Pu, 241 Pu/ 239 Pu and 242 Pu/ 239 Pu, were measured down to sample amounts of 70 fg. The ratio of 240 Pu/ 239 Pu was measured down to a sample amount of 0.1 fg, which corresponds to a PuO 2 particle with a diameter of 0.2 μm. Moreover, the signals of 239 Pu could be detected with a sample amount of 0.03 fg, which corresponds to the detection limit of 239 Pu of 0.006 fg as estimated by the 3-sigma criterion. 238 Pu and 238 U were clearly distinguished owing to the difference in the evaporation temperature between 238 Pu and 238 U. In addition, 241 Pu and 241 Am formed by the decay of 241 Pu can be discriminated owing to the difference in the evaporation temperature. As a result, the ratios of 238 Pu/ 239 Pu and 241 Pu/ 239 Pu as well as 240 Pu/ 239 Pu and 242 Pu/ 239 Pu in plutonium samples could be measured by TIMS with a continuous heating technique and without any chemical separation processes. [ABSTRACT FROM AUTHOR]

Abstract: Correlations among the alpha activity ratios of 238Pu/(239Pu+240Pu), the alpha specific activities of Pu and the atom % abundances of Pu isotopes were derived for the plutonium samples obtained from high burnup fuel samples from pressurized water reactors. Using the alpha activity ratios of 238Pu/(239Pu+240Pu) determined by alpha spectrometry, the alpha specific activities of Pu as well as the atom % abundances of the plutonium isotopes in the unknown samples were calculated without depending on mass spectrometry. The calculated alpha specific activities of Pu agreed with those determined by experiment within 2%, and the atom % abundances of the Pu isotopes agreed within 4% for 238Pu, 5% for 239Pu, 7% for 240Pu and 5% for 242Pu, respectively. In addition, an attempt was made to elucidate a correlation between the fuel burnup and the alpha activity ratio of 238Pu/(239Pu+240Pu) at a range of the burnup from 35.5 to 62.9 GWd/MtU. [Copyright &y& Elsevier]