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DOE OSTI2024

Primordial black hole sterile neutrinogenesis: sterile neutrino dark matter production independent of couplings

Abstract Sterile neutrinos (ν s s) are well-motivated and actively searched for hypothetical neutral particles that would mix with the Standard Model active neutrinos. They are considered prime warm dark matter (DM) candidates, typically when their mass is in the keV range, although they can also be hot or cold DM components. We discuss in detail the characteristics and phenomenology ofν s s that minimally couple only to active neutrinos and are produced in the evaporation of early Universe primordial black holes (PBHs), a process we called “PBH sterile neutrinogenesis”. Contrary to the previously studiedν s production mechanisms, this novel mechanism does not depend on the active-sterile mixing. The resultingν s s have a distinctive spectrum and are produced with larger energies than in typical scenarios. This characteristic enablesν s s to be WDM in the unusual 0.3 MeV to 0.3 TeV mass range, if PBHs do not matter-dominate the Universe before evaporating. When PBHs matter-dominate before evaporating, the possible coincidence of induced gravitational waves associated with PBH evaporation and astrophysical X-ray observations fromν s decays constitutes a distinct signature of our scenario.

Astronomy & Astrophysics↗

DOE OSTI2019

A simplified lithium vapor box divertor

A detached divertor plasma is predicted to be necessary to mitigate the heat fluxes and ion energy, and so sputtering, at the divertor plate of a fusion power plant. It has proven difficult in current experiments, however, to prevent the detachment front, once formed, from running up to the main plasma resulting in deterioration of pedestal performance. The lithium vapor box divertor localizes a dense cloud of lithium vapor away from the main plasma, in order to induce detachment at a stable, distant location. The vapor localization is created by local evaporation and nearby condensation, a configuration inaccessible for non-condensing seed impurities. This paper provides simulations of lithium vapor flow using the SPARTA direct simulation Monte Carlo (DSMC) code, in which the lithium vapor dynamics are governed by Li–Li collisions that should dominate in regions with little plasma. Inertia is included in this code, permitting the formation of shocks. The plasma model implemented in SPARTA is based on UEDGE results for the location of ionization and recombination. We find that a simplified lithium vapor box configuration, without baffles, provides robust stabilization of the detachment front and acceptable lithium vapor flow to the main chamber. Lithium is evaporated from a capillary porous surface on the private-flux side of the divertor, distant from the main plasma, and is condensed on the other side walls of the divertor chamber. The condensed lithium flows back to the evaporator through 2 cm internal diameter pipes. The capillary pressure differential at the surface of the evaporator is capable of overcoming MHD back-force in the piping, with a great deal of margin if a sandwich flow channel insert is implemented. Very little lithium should be accumulated on the first wall of the main chamber if it is maintained at 600 °C, as expected for a power-producing fusion system.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2021

The implications of future climate change on the blue water footprint of hydropower in the contiguous US

As the largest renewable energy source, hydropower is essential to the sustainability of the global energy market. However, a considerable amount of water can be lost in the form of evaporation from the associated multipurpose reservoirs, and hence enlarge the blue water footprint (BWF) of hydropower in a warming climate. To facilitate the sustainable management of both water and energy resources under the impact of climate change in the contiguous United States (CONUS), the BWF values of 143 major multipurpose reservoirs were evaluated during the historical period (1985–2014) and two future periods (2020–2049 and 2070–2099). The historical reservoir evaporation loss was calculated using the Landsat-based reservoir surface area and a new evaporation rate algorithm that considers the heat storage effect. Future projections of runoff availability, hydropower generation, and reservoir evaporation were estimated based on the downscaled climate model ensemble from phase 5 of the Coupled Model Intercomparison Project (CMIP5). It was found that the BWF for the CONUS is highly spatially heterogeneous, with an average value of 26.2 m 3 /MWh in the historical period. In the future, the BWF values are projected to increase under both Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. This is especially noticeable under RCP 8.5, which has an average BWF value of 30.2 m 3 /MWh for 2070–2099 (increasing by 15.3% from 26.2 m 3 /MWh). The uncertainty ranges increase even more, from 3.4 m 3 /MWh during 2020–2049 to 5.7 m 3 /MWh during 2070–2099. These findings can benefit water and energy resources management in identifying suitable environmental, economic, operational, and investment strategies for multipurpose reservoirs in a changing environment.

13 HYDRO ENERGY↗

DOE OSTI2025

Black hole explosions as probes of new physics

The final stage of black hole evaporation is a potent probe of physics beyond the Standard Model: Hawking-Bekenstein radiation may be affected by quantum gravity “memory burden effects,” or by the presence of “dark,” beyond-the-Standard-Model degrees of freedom in ways that are testable with high-energy gamma-ray observations. We argue that information on either scenario can best be inferred from measurements of the evaporation’s light curve and by correlating observations at complementary energies. We offer several new analytical insights in how such observations map on the fundamental properties of the evaporating black holes and of the possible exotic particles they can evaporate into. Published by the American Physical Society 2025

Federico, Kevin (ORCID:0009000708441977)↗

DOE OSTI2020

Tracking moisture sources of precipitation over Central Asia: A study based on the water-source-tagging method

Central Asia is a semi-arid to arid region that is sensitive to hydrological changes. We use the Community Atmosphere Model version 5 (CAM5), equipped with a water tagging capability, to investigate the major moisture sources for climatological precipitation and its long-term trends over Central Asia. Europe, the north Atlantic and local evaporation, which explain 33.2±1.5%, 23.0±2.5% and 19.4±2.2% of the precipitation, respectively, are identified as the most dominant moisture sources for northern Central Asia (NCA). For precipitation over southern Central Asia (SCA), Europe, the north Atlantic and local evaporation contributes 25.4±2.7%, 18.0±1.7% and 14.7±1.9%, respectively. In addition, the contributions of South Asia (8.6±1.7%) and Indian Ocean (9.5±2.0%) are also substantial for SCA. Modulated by the seasonal meridional shift of subtropical westerly jet, moisture originating from low- and mid-latitude is important in winter, spring and autumn, while northern Europe contributes more in summer. We also explain the observed drying trends over southeastern Central Asia in spring and over NCA in summer during 1956-2005. The drying trend over the southeastern Central Asia in spring is mainly due to the decrease of local evaporation and weakened moisture fluxes from the Arabian Peninsula and Arabian Sea associated with the warming Western Pacific. The drying trend over NCA in summer can be attributed to the decrease of local evaporation and reduced moisture from northern Europe due to the southward shift of the subtropical westerly jet.

Jiang, Jie↗

DOE OSTI2021

The Relationship between Precipitation and Precipitable Water in CMIP6 Simulations and Implications for Tropical Climatology and Change

It is well documented that over the tropical oceans, column-integrated precipitable water (pw) and precipitation (P) have a nonlinear relationship. In this study moisture budget analysis is used to examine this P–pw relationship in a normalized precipitable water framework. It is shown that the parameters of the nonlinear relationship depend on the vertical structure of moisture convergence. Specifically, the precipitable water values at which precipitation is balanced independently by evaporation versus by moisture convergence define a critical normalized precipitable water, pw nc . This is a measure of convective inhibition that separates tropical precipitation into two regimes: a local evaporation-controlled regime with widespread drizzle and a precipitable water–controlled regime. Most of the 17 CMIP6 historical simulations examined here have higher pw nc compared to ERA5, and more frequently they operate in the drizzle regime. When compared to observations, they overestimate precipitation over the high-evaporation oceanic regions off the equator, thereby producing a ‘‘double ITCZ’’ feature, while underestimating precipitation over the large tropical landmasses and over the climatologically moist oceanic regions near the equator. The responses to warming under the SSP585 scenario are also examined using the normalized precipitable water framework. It is shown that the critical normalized precipitable water value at which evaporation versus moisture convergence balance precipitation decreases as a result of the competing dynamic and thermodynamic responses to warming, resulting in an increase in drizzle and total precipitation. Statistically significant historical trends corresponding to the thermodynamic and dynamic changes are detected in ERA5 and in lowintensity drizzle precipitation in the PERSIANN precipitation dataset.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Radiative feedbacks on land surface change and associated tropical precipitation shifts

Changes in land surface albedo and land surface evaporation modulate the atmospheric energy budget by changing temperatures, water vapor, clouds, snow and ice cover, and the partitioning of surface energy fluxes. Here idealized perturbations to land surface properties are imposed in a global model to understand how such forcings drive shifts in zonal mean atmospheric energy transport and zonal mean tropical precipitation. For a uniform decrease in global land albedo, the albedo forcing and a positive water vapor feedback contribute roughly equally to increased energy absorption at the top of the atmosphere (TOA), while radiative changes due to the temperature and cloud cover response provide a negative feedback and energy loss at TOA. Decreasing land albedo causes a northwards shift in the zonal mean intertropical convergence zone (ITCZ). The combined effects on ITCZ location of all atmospheric feedbacks roughly cancel for the albedo forcing; the total ITCZ shift is comparable to that predicted for the albedo forcing alone. For an imposed increase in evaporative resistance that reduces land evaporation, low cloud cover decreases in the northern mid-latitudes and more energy is absorbed at TOA there; longwave loss due to warming provides a negative feedback on the TOA energy balance and ITCZ shift. Imposed changes in land albedo and evaporative resistance modulate fundamentally different aspects of the surface energy budget. However, the pattern of TOA radiation changes due to the water vapor and air temperature responses are highly correlated for these two forcings because both forcings lead to near-surface warming.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

Adhesion-force micro-scale study of desiccating granular material

Experiments on five-, four-, three- and two-wet-hydrophilic-grain clusters were performed to investigate evolution of adhesion of granular media during drying on the micro-scale. The experiments show that the adhesion-force of a cluster initially grows at most to three times the original value before decreasing to zero by the end of evaporation. The adhesion-force is composed of capillary pressure force acting over the liquid/solid contact surface area, and surface tension forces acting over the three-phase contact perimeter length. This is in contrast with most macro-scale phenomenological models, in which the only desaturation process variables affecting strength are suction and saturation. Both the contact surface area and contact perimeter length are reduced to zero upon complete liquid evaporation. The morphology of an evaporating water body evolves through slow flow controlled by evaporation rate, interrupted by various modes of fast air entry, which are non-equilibrium jumps of liquid/gas interfaces (Haines jumps). The instabilities involve large adhesion force discontinuities and substantial water mass reconfiguration with water flow in an extremely short time, which makes the process transient. The reconfigurations can reduce the original multi-grain water clusters to four-, three- and two-grain clusters by way of three different instability modes: of thin-sheet instability, or meniscus snap-through instability, depending on the sign of the Gauss curvature of the liquid surface, or finally, for two-grain bridges only, a liquid wire pinch-off. For larger meso-scale assemblies, however, the global adhesion-force evolution is little affected by the jumps. The air entries are potential sites for drying cracks. The (approximately) calculated capillary pressure for two- and three-grain clusters, in no cases is seen to reach high values, predicted from water retention curves.

Engineering↗

DOE OSTI2018

Bench Scale Study of Coating Formulations for Abatement of Mercury Vapor and Recovery of Mercury Spills

A sealant formulation has been developed that effectively mitigates human exposure to elemental mercury vapor evolving from spilled mercury. The sealant may be dispensed using a fogging methodology (for industrial settings) or a common spray bottle (for home or school settings). In parallel, the potential for Hg recovery using strippable coatings was evaluated. Four liquid coatings were evaluated: one fogging fixative (FX2) developed at INL for the containment of surface and airborne contamination and three commercially available strippable decontamination gels (Carboset 441, Encor 449, and Stripcoat TLC Free). Bench scale mercury vapor abatement tests were conducted in an enclosure using FX2 with the addition of a mercury absorbent and a mercury reactant. Testing with FX2 showed the reactant contributed significantly to reducing the rate of mercury evaporation. The reactant had a minimal impact on the mercury evaporation rate for the strippable coatings. The potential of strippable coatings to remove/recover mercury was inferred from the adhesive and cohesive performance of sprayable dilutions of the coatings applied to porous and non-porous surfaces. Testing provided the following results: • Mercury vapor concentration was reduced by a factor of 40 using the reactant enhanced FX2 solution, as well as with dilutions of Carboset and Encor. Dilute Stripcoat was less effective at reducing Hg evaporation. • A 100× reduction in Hg evaporation rate was achieved using a coating of FX + the Hg reactant (a.k.a. FX Hg), compared to uncoated Hg. • A 2× reduction in the Hg vapor accumulation rate was achieved using FX Hg, compared to the strippable coatings. • Strippability and adhesion tests show that dilutions of Carboset and Stripcoat can be stripped from a variety of indoor surfaces. Dilute Encor was not strippable. Results suggest FX Hg and dilute Carboset will likely reduce Hg vapor concentrations, in an indoor setting, to a level at or below the Occupational Safety and Health Administration 8-hour human exposure limit (0.1 mg/m3). FX Hg dispensed via fogging would increase worker safety during remediation and demolition of industrial facilities with high levels of elemental mercury contamination. When applied via spray bottle, FX Hg may provide a safe and convenient method for the mitigation of Hg vapor in residential or commercial settings (e.g., offices, homes, schools). This approach would be most beneficial where recovery of the spilled Hg is impractical. A sprayed then stripped application of dilute Carboset may provide a safe and convenient method for recovery of small Hg spills in residential and commercial settings. Further testing is required to determine if liquid Hg sufficiently adheres to the strippable coating to be recovered in this way. If it can be dispensed as a fog, dilute Carboset could be employed to recover Hg contamination in industrial settings. Testing of the foggability of dilute Carboset is required to assess this potential.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Acetonitrile Destruction in ETF Feed Solutions by UV/OX and Persulfate (Final Report)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Testing of UV Oxidation Process for Acetonitrile Destruction

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

An Evaluation of the Impact of Glycolate and Glycolate Mitigation on the Defense Waste Processing Facility Recycle Diversion Project Flowsheet

The Savannah River Site (SRS) Defense Waste Processing Facility (DWPF) processes radioactive High Level Waste (HLW) sludge solids from the Concentration, Storage, and Transfer Facilities (CSTF); which includes the SRS Tank Farm and Evaporator facilities, and a concentrated Cs-137 laden stream and a Monosodium Titanate (MST) and sludge solids stream from the SRS Salt Waste Processing Facility (SWPF). The waste is chemically adjusted with acids and reductant (currently with 50 wt.% nitric acid and ~90 wt.% formic acid, but eventually formic acid will be substituted with ~70 wt.% glycolic acid), and frit is added so that a durable, borosilicate glass waste form can be produced when the material is vitrified in the melter. As a result of the evaporation of water during both the melter feed preparation and the melter feed vitrification steps in DWPF, a recycle waste stream is generated, neutralized, and sent back to the CSTF. The recycle waste is a dilute aqueous stream originating from the collection of condensate liquids containing some minor sludge, MST, and frit solids and other waste components resulting from melter feed entrainment during foamover events and transfer of volatile species into the condensate. The recycle stream volume is significant and is expected to approach 3 million gallons per year once SWPF reaches full operation, requiring the use of multiple large CSTF tanks for storage. The recycle waste is currently collected in the SRS Tank Farm and periodically evaporated in the 242-16H (2H) Evaporator to conserve storage space.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Acetonitrile Destruction and Fate of Organics in the Reverse Osmosis System at the ETF

The Hanford Site Effluent Treatment Facility (ETF) currently treats aqueous waste streams that include condensates from the 242-A evaporator, leachate from the Environmental Restoration Disposal Facility (ERDF), as well as laboratory wastes and, in the future, will treat liquid effluents from the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and Integrated Disposal Facility (IDF) leachate. Liquid effluents from the WTP will have significant concentrations of acetonitrile. Acetonitrile is formed by reaction of nitrates and sugar in the WTP low activity waste (LAW) melters and is prevalent in the submerged bed scrubber (SBS) and wet electrostatic precipitator (WESP) liquid effluents from WTP off-gas treatment. When these liquids are concentrated in the WTP Effluent Management Facility (EMF) evaporator in the direct feed low activity waste (DFLAW) flow-sheet, testing has shown that the majority of the acetonitrile partitions to the evaporator condensate. Since the evaporator condensate is directed to the ETF, this creates a potential issue with the ETF waste acceptance criteria. Consequently, there is a need to validate flow-sheet assumptions on the fate of acetonitrile and other organics within the ETF. The present plan includes the addition of a steam stripper to the ETF to remove acetonitrile. There is, therefore, also a need to determine a suitable method to destroy acetonitrile in the overhead condensate stream from the new steam stripper. Washington River Protection Solutions, LLC (WRPS) previously contracted with Atkins and the Vitreous State Laboratory (VSL) of The Catholic University of America (CUA) to perform development and testing work to evaluate potential methods for destruction of acetonitrile in WTP secondary liquid effluents. Based on the results of that work, WRPS requested that follow-on testing be conducted to further evaluate acetonitrile destruction in the steam stripper condensate using ultraviolet oxidation (UV/OX) with persulfate. WRPS also requested testing to assess the rejection rate of organics in the reverse osmosis (RO) system installed in the ETF. This report presents the results from testing to address those needs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2024

High performance heat exchangers for next generation hybrid cooler (CRADA Final Report)

The evaporative cooling process has been successfully deployed in multiple energy conversion processes such as power generation, process cooling, heating, ventilation & cooling (HVAC), and commercial and industrial refrigeration. The heat exchanger is a very common yet extremely critical component of such systems. The device is important since the performance of the overall cooling system heavily relies on the thermal-hydraulic efficiency of the heat exchanger. The possible wet operation as evaporative cooling heat exchanger complicates the issue. Indeed, based on the hybrid nature of operation (fully dry, partially wet, fully wet) the efficiency can vary significantly and can cause performance variation for the whole system. Understanding the importance of the issue, Oak Ridge National Laboratory (Contractor) and Baltimore Aircoil Company (Participant) propose an activity focused on the analysis of the existing heat exchanger technology used in air and evaporative cooling processes and design, development and demonstration of a novel heat exchanger design based on porous materials. The potential candidates include metallic wire meshes and metal foams carefully designed for the proposed application. Prior research has indicated that these materials have great potential for deployment in thermal systems, particularly heat sinks and heat exchangers. It is expected that the successful completion of the project will lead to novel heat exchanger technology for hybrid systems (capable of dry and wet operation) by exploring newly emerging materials and their potential for heat transfer application. The overall goal is to develop a next generation heat exchanger technology which can be deployed in evaporative cooling systems. The impact of the such development is significant since, it will not only make the overall system highly efficient but will also, reduce the total refrigerant charge in the heat exchanger, a critical aspect for the deployment of refrigerants with lower Global Warming Potential (GWP).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2021

Reducing Sample Loss in Measurement of Heat of Vaporization of Ethanol/Gasoline Blends by Differential Scanning Calorimetry/Thermogravimetric Analysis

Higher gasoline Heat of Vaporization (HOV) can enable higher compression-ratio direct injection spark ignition engines by providing evaporative cooling that effectively increases fuel knock resistance. Methods to directly measure this fuel property in complex gasoline samples are not well developed. The objective of the present study was to further improve a Differential Scanning Calorimetry/Thermogravimetric Analyzer (DSC/TGA) method to measure the total and partial HOV of gasoline. Ten market gasoline samples were chosen to have a wide range of properties to assess the method's capability across the entire volatility range with an emphasis on understanding how well the method captures the initial 10 percent (%) of sample evaporation and how much sample is left unevaporated at the end of the experiment. Modifications to the sample preparation/introduction method as well as to the instrument itself were made to reduce initial sample losses which included measurements of the HOV at 10 degrees C and 5 degrees C (in a cold chamber) as well as under (uncontrolled) ambient conditions. Experimental results from the DSC/TGA were compared to calculated total HOV results based on Detailed Hydrocarbon Analysis (DHA). Results from the two methods agreed very well with the difference being 5% or less in almost every case. In addition, the repeatability of the method was investigated by analyzing samples in triplicate at the three temperatures investigated. One valuable conclusion from the study was that the lower temperatures of 10 degrees C and 5 degrees C enabled more reproducible measurements for both total and partial HOV. This improved precision may be caused by the fact that temperature control in the cold chamber was more reliable than the ambient laboratory temperature control. Additionally, cold chamber experiments, due to ergonomic limitations, did not allow for the use of a lid on the sample pan. The reproducibility of the evaporation rate was found to be highly dependent on the pan/lid fit which can vary significantly such that elimination of the lid improved measurement precision while operation at sub-ambient temperature slowed the evaporation rate. Results detailing sample preparation and instrument modifications as well as a detailed comparison of total and partial HOV results are presented.

ADVANCED PROPULSION SYSTEMS,BIOMASS FUELS↗

DOE OSTI2026

The Fate of Nucleated Black Holes in de Sitter Quantum Gravity

The Euclidean Nariai geometry has long been proposed as the instanton describing the nucleation of maximal-mass black holes in de Sitter space. We place this interpretation on firmer footing by showing that, once an observer is included, the gravitational path integral produces the imaginary phase required for a transition rate. As a warmup, we revisit the Hawking-Moss instanton and, as a byproduct, find that scalar fields can enhance black-hole nucleation, suggesting a quantum-gravity bound on scalar potentials with de Sitter solutions. We then study the subsequent semiclassical evolution of the nucleated black hole. We show that the previously claimed "anti-evaporation" channel is unphysical, arising from a quantum state with singular horizons. In a smooth state, the black hole instead undergoes standard thermal Hawking evaporation. We verify explicit agreement with the no-boundary state and argue that this evaporation is not subject to large quantum-gravity corrections. The nucleated black hole thus evaporates completely back to the maximally-entropic empty de Sitter vacuum, making the full process a Boltzmann fluctuation.

FOS: Physical sciences↗

NASA NTRS1972

Study of mechanism which causes film formation on mercury surfaces

The mechanism by which small quantities of dissolved tin, sodium, and lithium lower the rate of evaporation of mercury in vacuum is determined. An apparatus was built in which dilute amalgams could be prepared and studied in an oxygen-free environment before being exposed to oxygen under controlled conditions. The apparatus was able to maintain a pressure of less than 1.3 x 0.000001 N/sqm (10 to the minus 8th power torr) of gases and vapors other than mercury and less than 1.3 x 10 to the minus 8th N/sq m (10 to the minus 10th power torr) partial pressure of oxygen; also, it provided for mechanical sweeping of the liquid metal surfaces in the vacuum environment. The rates of evaporation of pure mercury and of dilute amalgams of tin (52 ppm), sodium (229 ppm), and lithium (165 ppm) were determined at temperature between 25 and 55 C both before and after 70 minute exposures to an approximately 270 N/sq m (2 torr) pressure of oxygen. The rates of evaporation of the pure mercury and the amalgams as first prepared were similar but the rates for the amalgams were reduced by at least 80% at 25 C as a result of the exposure to oxygen. The effect of the oxygen treatment could be completely removed by sweeping the amalgam surfaces. It was concluded that the reduced rates of evaporation resulted from the formation of transparent, insoluble, oxide films on the amalgam surfaces.

Frohnsdorff, G.↗

NASA NTRS1972

Anomalous FIM images of tungsten.

Observation of unusual field-ion images consisting of bright bands of variable width parallel to the 111 (in carets) zones in tungsten at 78 K. Typical conditions for the effect are: pulse width from 1 to 50 microsec and pulse height adjusted so that five to ten pulses are required to remove one (110) plane. The influence of a number of accessible variables was studied and the results lead to a two-mechanism model for field evaporation involving (1) a slow process requiring helium promotion and (2) unpromoted evaporation when the local helium supply is depleted at high rates. The model implies that helium diffusion is rate-limiting in the promotion mechanism and leads to a migration energy of about 0.15 eV during field evaporation. There is a measurable difference in end form in the limits of high- and low-field evaporation rates. High rates are nearly isotropic and yield a more hemispherical end form.

Hren, J. J.↗