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[en] Biologically stable 90Y-labelled albumin microspheres (AMS) were developed by optimizing the process of their preparation. Three formulations of 90Y-AMS were initially prepared with high radiolabelling yield but depending on the step when the radionuclide 90Y and DTPA chelator were added, radiolabelled microspheres with different in vitro and in vivo stability were obtained. DTPA was proved as a useful chelating agent that tightly links radionuclide 90Y to albumin. Also, AMS radiolabelled via DTPA during preparation and before microspheres stabilization, showed significant in vitro and in vivo stability ready for the potential use in selective internal radiation therapy. © 2019 Elsevier Ltd
[en] The probabilities of locating peaks with a high relative peak-area uncertainty were determined empirically with nine types of peak-location software used in laboratories engaged in gamma-ray spectrometry measurements. It was found that it is not possible to locate peaks with a probability of 0.95, when they have a relative peak-area uncertainty in excess of 50%. Locating peaks at these relatively high peak-area uncertainties with a probability greater than 0.95 is only possible in the library-driven mode, where the peak positions are supposed a-priori. The deficiencies of the library-driven mode and the possibilities to improve the probabilities of locating peaks are briefly discussed. © 2019 Elsevier Ltd
[en] The Next Generation Safeguard Initiative (NGSI) includes an effort to determine the mass content of fissile isotopes contained within spent fuel through the spectroscopy of high-energy delayed gamma rays. Studies being performed indicate the primary difficulty is the ability to detect the desired signal in the presence of the intense background associated with spent fuel fission products. An enabling technology for this application is high-resolution high-purity germanium (HPGe) detectors capable of operating efficiently in at extremely high count rates. This presentation will describe the prospects of high-rate germanium detectors and delayed-gamma techniques, primarily discussing the efforts to merge these into a unique and viable system for measuring spent fuel
[en] In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr_3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr_3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr_3:Ce detectors have been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides "1"5"2Eu and "1"3"3Ba have been identified in a sample that is dominated by "1"3"7Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large "1"3"7Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr_3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr_3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr_3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.
[en] Actinium-225 and "2"1"3Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of "2"2"5Ac. The high energy proton spallation reaction on natural thorium metal target has been utilized to produce millicurie quantities of "2"2"5Ac. The results of sixteen irradiation experiments of Th metal at beam energies between 78 and 200 MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridge National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes as well as for some of the fission products are presented. The cross sections for production of "2"2"5Ac range from 3.6 to 16.7 mb in the incident proton energy range of 78 to 192 MeV. Based on these data, production of Curie quantities of 225Ac is possible by irradiating a 5.0 g cm"-"2"2"3"2Th target for 10 days in either BNL or LANL proton irradiation facilities.
[en] In this paper, a modified version of the Direct LSC method to correct for quenching effect was investigated for the determination of bio-originated fuel content in fuel samples produced from multiple biological starting materials. The modified method was found to be accurate in determining the percent bio-originated fuel to within 5% of the actual value for samples with quenching effects ≤43%. Finally, analysis of highly quenched samples was possible when diluted with the exception of one sample with a 100% quenching effect.
[en] Neutron fluence and neutron ambient dose equivalent, , are important physical quantities for neutron radiation protection and monitoring. They can be deduced from neutron spectrum, which is usually measured by multisphere system with proper unfolding methods. Novel unfolding methods on the basis of artificial intelligence, mainly artificial neural networks (ANNs), have been researched and developed. However, without normalization on network inputs, ANNs can not be applied to accommodate demands of various neutron field measurements for neutron spectrum unfolding in practice, because the neutron spectra for training the ANNs are mostly extracted from IAEA (2001), the integrals of which over neutron energy are unit fluences. Moreover, derived from an unfolded normalized spectrum, the true values of neutron fluence and are never to know. In this work, three normalization methods—zero-mean normalization method, min-max normalization method, and maximum-divided normalization method were used to process with the inputs of generalized regression neural networks (GRNNs), and a new method was proposed for neutron fluence and estimations derived from unfolded neutron spectrum based on GRNNs for the first time. Sixty-three neutron spectra were unfolded based on GRNNs with use of three normalization methods, and the corresponding neutron fluences and were obtained and compared. From the testing results, the GRNNs with the maximum-divided method is most effective to unfold neutron spectrum and to evaluate neutron fluence and . The feasibility of the method was further studied through experiments by using Bonner sphere spectrometer in well characterized 241Am–Be neutron field.
[en] Highlights: • Characterization and calibration of radon monitors. • Influence of absolute humidity on detectors employed in radon monitors. • Electromagnetic compatibility (EMC) of radon monitors. Improvement of susceptibility. - Abstract: The employment of different instruments for radon continuous measurements within the Italian Radon mOnitoring Network (IRON), mostly INGV, Algade AER and Airthings Corentium instruments, requires a uniform characterization and calibration protocol for the results to be comparable in a rigorous way. A 56 L stainless steel radon chamber with a sensitivity of 0.95 ± 0.01 Bq m−3 per pulse h−1 has been used and validation of Algade AER, Airthings Corentium and Durridge RAD7 radon monitors equipped with solid-state detectors operated at different absolute humidity values has been performed, extending their operative range. Robustness to atmospheric electromagnetic phenomena of INGV and Algade AER instruments has been investigated and, for the former instrument, improved.
[en] Highlights: • The design parameters of RPT were experimentally evaluated. • The theoretical results reported in the literature of theoretical evaluation were validated. • Scandium-46 was found to be the most suitable radioisotope for RPT studies. • NaI (Tl) detector with a crystal size of 5 cm × 5 cm was found to be most efficient. • Three detectors in a particular plane were sufficient to obtain accurate results. - Abstract: In recent years, radioactive particle tracking (RPT) has emerged as a powerful noninvasive technique for characterization and visualization of flow in opaque multiphase flow reactors. This technique has been applied to a variety of multiphase flow reactors largely based on the theoretical framework for optimal design and performance parameters. No systematic evaluation and validation of the design and performance parameters of the RPT technique has been reported in the literature thus far. Consequently, the theoretical framework for the design of RPT experiments has had limited scalability and application to a wide variety of flow systems. Thus far, design of a “good” RPT experiment continues to be an art, no matter how much the richness of flow of information that the experimental method brings. The present work reports systematic experimental evaluation of design parameters for an optimal RPT experiment and validation of the theoretical results reported in literature. The experiments were performed in a carefully designed setup in which precise positioning of the tracer particle was made possible. The experiments assess the effect of various parameters on the performance of the RPT experiment, such as the choice of radioactive isotope, activity, gamma-ray energy, size of the detector, and relative positioning of detectors. Finally, a set of recommendations based on experimental work are provided to “optimally” perform the RPT experiment in any single or multiphase reactor.
[en] Highlights: • Neutron radiation field inside a PETtrace biomedical cyclotron were measured. • Measurements were carried out using activation foils. • Neutron contributions of thermal, epithermal and fast were evaluated. • The irradiations were performed using the intermittent irradiation method. - Abstract: This work aimed at assessing the neutron radiation field with activation foils around of the PETtrace biomedical cyclotron. Activation foils of gold, gold covered with cadmium, indium and nickel was used to evaluate the thermal, epithermal and fast neutron contributions, respectively. The irradiations of the activation foils were performed using the intermittent irradiation method to conciliate the measurements with the routine 18F production. The evaluated points showed the contributions of the thermal, epithermal and fast neutrons due to interaction with the vault room, cyclotron accelerator and main cyclotron components.