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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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Correlated variational treatment of ionization coupled to nuclear motion: Ultrafast pump and ionizing probe of electronic and nuclear dynamics in LiH
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Foaming during Nuclear Waste Melter Feeds Conversion to Glass: Application of Evolved Gas Analysis
During the final stages of batch-to-glass conversion in a waste-glass melter, gases evolving in the cold cap produce primary foam, the formation and collapse of which control the glass production rate via its effect on heat transfer to the reacting batch. We performed quantitative evolved gas analysis (EGA) for several HLW melter feeds with temperatures ranging from 100 °C to 1150 °C, the whole temperature span in a cold cap. EGA results were supplemented with visual observation of batch-to-glass transition using the feed expansion tests. Upon heating, most of the gases—mainly H2O, CO2, NO, NO2, N2 and O2—evolve at temperatures below 700 °C and escape directly to the atmosphere through open porosity. However, as open porosity closes when enough glass-forming melt appears at 720 °C, the residual gas evolution leads to the formation of primary foam. We found that primary foaming is mostly caused by the decomposition of residual carbonates, though oxygen evolution from iron-redox reaction can also play a role. We also show that the gas evolution shifts to a higher temperature when the heating rate increases. The implications for the mathematical modeling of foam layer in the cold cap are presented.
A Method for Determining Bulk Density, Material Density, and Porosity of Melter Feed During Nuclear Waste Vitrification
Glassmelting efficiency largely depends on heat transfer to reacting glass batch (melter feed), which in turn is influenced by the bulk density (ρ b ) and porosity (ϕ) of the reacting feed as functions of temperature ( T ). Neither ρ b ( T ) nor ϕ( T ) functions are readily accessible from direct measurements. For the determination of ρ b , we monitored the profile area of heated feed pellets and calculated the pellet volume using numerical integration. For the determination of ϕ, we measured the material density of feeds quenched at various stages of conversion via pycnometry and then computed the feed density at heat‐treatment temperature using thermal expansion values of basic feed constituents.
MELCOR DEMONSTRATION ANALYSIS OF ACCIDENT SCENARIOS AT A SPENT NUCLEAR REPROCESSING PLANT.
Abstract not provided.
Nuclear Facility Safety Enhancement Using Sandia National Laboratories' Computer Codes.
Abstract not provided.
Manipulating strong electromagnetic fields with the average transverse momentum of relativistic nuclear collisions
Abstract We show that an event-shape engineering based on the mean transverse momentum of charged hadrons, $$[p_t]$$ [ p t ] , provides an optimal handle on the strength of the magnetic field created in central heavy-ion collisions at high energy. This is established through quantitative evaluations of the correlation existing between the event-by-event magnetic field produced by the spectator protons in 5.02 TeV Pb + Pb collisions and the event-by-event $$[p_t]$$ [ p t ] at a given collision centrality. We argue that the event selection based on $$[p_t]$$ [ p t ] provides a better handle on the magnetic field than the more traditional selection based on the event ellipticities. Advantages brought by this new method for the experimental search of the chiral magnetic effect are discussed.
Earthquake response of head-mounted equipment in advanced nuclear reactors
The seismic response of safety-related equipment mounted on the head of an advanced reactor, including pumps, control rod drive mechanisms, and reactor monitoring devices, will affect the design and layout of many advanced reactors. High earthquake-induced accelerations in such equipment may challenge their seismic qualification and trigger the need for additional support framing on the reactor head. Base isolation is a design solution that can drastically reduce seismic demands on equipment. This article describes a set of earthquake-simulator experiments conducted on a scale-model of a base-isolated reactor vessel including four representations of head-mounted equipment, with frequencies spanning from 4.5 to 27 Hz. Dynamic responses of the head-mounted equipment, including displacements, accelerations, and strains, were measured in the experiments for three support conditions: conventional, and seismically isolated using single concave Friction Pendulum (SFP) bearings and triple Friction Pendulum (TFP) bearings. Seismic isolation was effective at reducing equipment responses (accelerations, displacements, and strains) with respect to those in the conventionally supported vessel across a range of seismic inputs. Companion numerical studies highlight the accuracy to be expected in the calculation of different response quantities for lightly damped equipment. The importance of characterizing damping in head-mounted, safety-related equipment through physical experiments to support design and risk assessment is made clear through the numerical simulations.