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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Densification of non-radioactive porous siliceous particles loaded with cesium potassium copper hexacyanoferrate by spark plasma sintering
In the development of a conditioning process for cesium-bearing sorbents from the decontamination of aqueous waste streams, the treatment of a granular material composed of (Cs,K) 2 CuFe(CN) 6 loaded onto mesoporous silica particles has been investigated in an additive-free two-step conditioning process involving (i) calcination at 1000 °C to remove volatile species and (ii) densification by spark plasma sintering. A 92.0 % dense pellet was obtained after 10 min sintering at 850 °C under 100 MPa. Density and microstructural measurements indicate that densification is first driven by the viscous flow of a vitreous phase containing Cs, formed during calcination. Additionally, the density of the sample then increases further during sintering by grain boundary diffusion. However, a limited but non negligible part of cesium is lost during densification.
Determination of human γδ T cell–mediated cytotoxicity using a non-radioactive assay system
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Melting behaviour of simulated radioactive waste as functions of different redox iron-bearing raw materials
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Oxide Layers in Ni-doped FeCrAl Alloy in 320°C Radioactive Hydrogenated Water
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Processes controlling helium bubble dynamics at varying temperatures in simulated radioactive materials
Alpha-radiation damage is known to degrade materials exposed to harsh radiation environments via swelling and embrittlement by nano-scale helium bubbles. How these bubbles grow under varying temperature is essential to understanding and predicting material failure and optimization. Using in situ X-ray scattering, we probed ≈1012 bubbles before, during and after annealing at different temperatures in He-implanted aluminum to reveal a critical growth activation temperature that depends strongly on the helium implantation conditions. An analysis of the data aided by our molecular dynamics simulations identifies multiple temperature-dependent bubble growth mechanisms above and below the critical growth activation temperature. Moreover, the irreversible bubble growth that occurs after annealing for ≈4 h was evaluated using dislocation dynamics and found to negligibly affect the yield strength but may affect subsequent bubble growth at temperature. These in situ results provide valuable insight into bubble growth never observed before and reveal, for the first time, bubble shrinkage after cooling.
Prediction of radioactivity releases for a Long-Term Station Blackout event in the VVER-1200 nuclear reactor of Bangladesh
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Development, validation and implementation of multiple radioactive particle tracking technique
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Localization of a radioactive source in an urban environment using Bayesian Metropolis methods [Bayesian Metropolis methods for source localization in an urban environment]
Here, we present a method for localizing an unknown source of radiation in an urban environment using a distributed detector network. This method employs statistical parameter estimation techniques, relying on an approximation for the response of a detector to the source based on a simplified model of the underlying transport phenomena, combined with a Metropolis-type sampler that is modified to propagate the effect of fixed epistemic uncertainties in the material macroscopic cross sections of objects in the scene. We apply this technique to data collected during a measurement campaign conducted in a realistic analog for an urban scene using a network of six mobile detectors. Our initial results are able to localize the source to within approximately 8 m over a scene of size 300 m 200 m in two independent trials with 30 min count times, including a characterization of the uncertainty associated with the poorly known macroscopic cross sections of objects in the scene. In these measurements, the nearest detectors were between 20 m to 30 m from the source, and recorded count rates between approximately 3 and 13 times background. A few detectors had line-of-sight to the source, while the majority were obscured by objects present in the scene. After extending our model to account for the orientation of the detectors and correcting for anomalies in the measurement data we were able to further improve the localization accuracy to approximately 2 m in both trials.
MuSIC@Indiana: An effective tool for accurate measurement of fusion with low-intensity radioactive beams
The design, construction, and characterization of the Multi-Sampling Ionization Chamber, MuSIC@Indiana, are described. This detector provides efficient and accurate measurement of the fusion cross-section at near-barrier energies. The response of the detector to low-intensity beams of 17,18 O, 19 F, 23 Na, 24,26 Mg, 27 Al, and 28 Si at E lab 50–60MeV was examined. MuSIC@Indiana was commissioned by measuring the 18 O+ 12 C fusion excitation function for 11 < E cm < 20 MeV using CH 4 gas. Here, a simple, effective analysis cleanly distinguishes proton capture and two-body scattering events from fusion on carbon. With MuSIC@Indiana, measurement of 15 points on the excitation function for a single incident beam energy is achieved. The resulting excitation function is shown to be in good agreement with literature data.
Tracking the location of a road-constrained radioactive source with a network of detectors
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LSTAR — An isobar separator for expanding radioactive ion beam production at the Cyclotron Institute, Texas A&M University
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The new JENSA gas-jet target for astrophysical radioactive beam experiments
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Sub-MeV ultra-compact linac for radioactive isotope sources replacement, non-destructive testing, security and medical applications
RadiaBeam Technologies, LLC has developed an inexpensive, hand-portable 180 keV electron accelerator to replace 57 Co radionuclide sources in Cascade Header Enrichment Monitor detectors. We used two innovative technologies in our design: a Ku-band (1 cm wavelength) magnetron, and a split accelerating structure design to reduce manufacturing costs. In this paper, we will discuss the accelerator, including X-ray convertor and accelerating structure design. The results of RF measurements of a Ku-band split structure prototype will also be reviewed. Other applications of Ku-band linacs include compact backscatter and transmission X-ray security inspection systems, as well as computed tomography (CT) systems for luggage and parcel screening. The main requirement for luggage inspection systems is that the X-ray source must be extremely compact. Further, the required energies should cover the range from 180 keV to 1 MeV. In this paper, we will discuss the linac’s energy scalability and other modifications that will enable our technology to address these applications.