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At least 19 records

Neutron capture measurements at UMass lowell research reactor

A new facility was designed around the thermal column beam port of the 1 MW Research Reactor at the University of Massachusetts Lowell. Thermal neutrons are collimated to a 1-inch diameter beam and incident on samples to induce the radiative neutron capture. New measurements of capture gamma rays are planned for Mn, Cu, Ni, Cr, and Gd samples in the next few years. The experiments will be carried out in close collaboration with the ENSDF (Evaluated Nuclear Structure Data File) evaluation group at Brookhaven National Laboratory. The gamma rays are measured using an array of high-resolution HPGe detectors. Some of the HPGe detectors use active Compton shields that were designed from scintillation detectors and improve significantly the signal-to-background in the measured gamma-ray spectra with HPGe. The experimental spectra will be validated by the GEANT4 simulations of the array and theoretical models of the emission of gamma rays from the compound nucleus. In conclusion, the new experimental results on the capture gamma ray intensities will be incorporated in future ENSDF evaluations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Nanohybrid of Cu2O-Ti3C2Tx as a Silver-Free MXene Sorbent for Iodine Gas Capture from Nuclear Waste

The capture of volatile radioiodine from nuclear fuel reprocessing off-gas streams remains a critical challenge due to the high volatility, long half-life of 129I, and biological uptake of iodide from the environment. Although silver-based sorbents provide strong iodine chemisorption, their high cost and regulatory classification as mixed radioactive-hazardous waste motivate the development of alternative materials. Here, we report a silver-free Cu2O-Ti3C2Tx MXene hybrid for iodine gas capture at 150 °C. Structural and compositional analyses confirm the formation of Cu2O nanoparticles on Ti3C2Tx nanosheets and their subsequent conversion to thermodynamically stable CuI upon static iodine gas exposure, achieving an iodine mass loading of up to 1115 mg/g. These results demonstrate the potential of Cu2O-Ti3C2Tx MXene as a copper-based alternative to silver sorbents for elevated-temperature iodine gas capture.

iodine gas capture

Optimal Design and Operation of a Solvent-Sorbent Hybrid Capture Process for Minimizing the Cost of High Capture

High capture can cause a significant increase in energy penalty if the appropriate technology/technologies are not utilized. The optimal technology for bulk capture is not necessarily the optimal technology for polishing capture (i.e., high extent of capture from the flue gas with very low partial pressure of CO2). This work investigates the use of MEA for bulk capture with the polishing capture being accomplished by a functionalized metal organic framework (MOF).

Kasturi, Pooja

Nondestructive time-of-capture, location and velocity sensing in intact capture

Velocity sensing of hypervelocity particles was a significant field of interest from the 1960s to 1970s. Generically, velocity sensing has been approached by either of two methods: first, detecting direct plasma or light emissions onto a solid surface, or second, performing time-of-flight by film penetration, or by detecting charged particles passing a static electric field. Impact plasma techniques required the destruction of the particles. Multiple-film penetrations were also destructive, especially for small particles. There is a need for an integrated, reliable, and simple location and velocity sensor compatible to our intact capture underdense medium without contributing additional damage to the captured particle. Since cometary dust, like cosmic dust, is essentially randomly distributed, knowing the time of the dust capture and the location of the capture on the collector permits the identification of the specific dust particle captured. Velocity information helps to determine the trajectory of the dust particle. Our discovery of a very suitable acoustic sensor and fruitful experimental results have led to the realization of a flight velocity sensor with intact capture underdense media.

Tsou, Peter

Beta-Amino Carboxylate (BAC) non-aqueous physical solvents for enhanced CO2 separations in pre-combustion carbon capture, industrial CO 2 capture, and biogas upgrading processes

Novel beta-amino carboxylate (BAC) solvents have been synthesized and tested to efficiently capture carbon dioxide (CO 2 ) from process gas streams with CO 2 partial pressure intermediate between pre-combustion and post-combustion capture. The BAC solvents have molecular structures characterized by alkyl-substituted amides or esters containing a secondary amine functional group on the second carbon from the carbonyl carbon (referred to as the beta “β” carbon). The ester or amide functional group combined with optimal steric crowding around the amine nitrogen by proximate alkyl groups are tailored to modify the strength of CO 2 binding in the solvent. The solvents possess high CO 2 solubilities and high gas selectivity including good CO 2 /H 2 O selectivity and can be utilized for CO 2 absorption over a range of partial pressures. Due to low volatility, many of the solvents can be operated at or above ambient temperature which eliminates solvent chilling and allows regeneration using low grade waste heat. These novel solvents offer an opportunity for efficient carbon capture for a range of applications including biogas upgrading, hydrogen production, and pre-combustion carbon capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH

Challenges in Product Selectivity for Electrocatalytic Reduction of Amine-Captured CO 2 : Implications for Reactive Carbon Capture

CO 2 is a potential feedstock for carbon-based fuels or materials, but is only available in dilute streams. Integrated processes for CO 2 capture and conversion directly valorize the CO 2 captured by sorbent materials, skipping the energetically expensive sorbent regeneration step. Amines are the most heavily studied liquid-phase sorbent materials for CO 2 capture from dilute streams. Amines react with CO 2 in a 2:1 ratio to form the corresponding ammonium carbamate. Ammonium carbamate [NH 4 ][H 2 NCO 2 ] was tested as the substrate using the highly selective and robust CO 2 -to-formate reduction electrocatalyst [( tBu POCOP)Ir(H)(NCCH 3 ) 2 ], where ( tBu POCOP) is the tridentate pincer ligand 2,6-bis(di tert -butyl-phosphonito). When ammonium carbamate was used as the substrate instead of CO 2 , only hydrogen was produced. An equivalent electrolysis with ammonium hexafluorophosphate with CO 2 also resulted in primarily hydrogen. Methyl carbamate and urea were also tested as substrates as proxies for carbamate that do not contain an equivalent of ammonium, and there was also negligible reduction to carbon-based products. These results indicate that the loss of selectivity observed for aminecaptured CO 2 , or ammonium carbamate, is likely due to the generation of the acidic ammonium equivalent as well as the greater challenge of reducing carbamate compared to CO 2 . This study illustrates that catalysts with high selectivity for concentrated CO 2 can favor hydrogen evolution and loss of carbon-based products when amine-captured CO 2 is used instead.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH

Demographic Microsimulator for Integrated Urban Systems: Adapting Panel Survey of Income Dynamics to Capture the Continuum of Life

Agent-based models (ABMs) in transportation modeling simulate activity and travel decisions at the disaggregate level of households and individuals. To do this, ABMs require detailed and realistic information on agents’ socioeconomic and demographic characteristics. Various synthetic population generators have been proposed to address this need. However, most of those currently in practice are cross-sectional in nature and do not account for the dynamics within households and individuals as they progress through life events over time. This is a major shortcoming, as literature has shown that transportation decisions are affected by the transition between and co-occurrence of life cycle events. While some demographic evolution simulators have been proposed to address this issue, they are developed using cross-sectional data and capture only a small set of life cycle events and their interdependence. Addressing these drawbacks, we propose a demographic microsimulator (DEMOS) that captures the “continuum of life” by considering a range of household- and individual-level life cycle events. DEMOS is developed using the Panel Survey of Income Dynamics, one of the world’s longest-running longitudinal surveys. The DEMOS submodels consider key life cycle events that are influenced by agents’ demographic variables. DEMOS is applied to evolve the population of the San Francisco Bay Area over a 9-year horizon. Results demonstrate how DEMOS generates life trajectories and how DEMOS outputs match the observed demographic trends. DEMOS is expected to enable longitudinal analysis in the context of ABMs and expand ABMs analyses relating to dynamic processes such as household-level vehicle transactions.

Demographic evolution

Designing a Robust MEA-Based Post-Combustion Carbon Capture Process with Capture Rate Guarantees

This work presents an application of the nonlinear two-stage robust optimization solver PyROS to the model-based design and operation of a monoethanolamine scrubbing process for CO<sub>2</sub> capture under epistemic uncertainty. Through this application, risk-averse process designs are successfully obtained for CO<sub>2</sub> capture targets ranging from 90% to over 99%. In particular, the risk-averse solutions for CO<sub>2</sub> capture targets of up to 98% are shown to be only marginally more expensive than their nominally optimal counterparts. Thus, the results demonstrate the utility of recently developed nonlinear robust optimization approaches for the solution of large-scale chemical process models under uncertainty.

20 FOSSIL-FUELED POWER PLANTS

Techno-economic Analysis and Optimization of Point Source Solvent-Based Carbon Capture Systems at High CO2 Capture Levels for NGCC Power Plants

This poster was presented at the 2024 FECM / NETL Carbon Management Research Project Review Meeting held during Aug 5-9, 2024. It summarizes the research done as a part of CCSI2 for determining the optimal design and operating conditions of an MEA solvent-based carbon capture system connected to a commercial scale NGCC plant, operating at CO2 capture levels beyond 90%. The techno-economic optimization approach is outlined, along with the trends of key cost and performance indicators across high capture levels.

Deshpande, Anuja

Ion dipole capture cross sections at low ion and rotational energies - Comparison of integrated capture cross sections with reaction cross sections for NH3 and H2O parent-ion collisions.

The numerical capture cross section is calculated from the capture ratio, defined as the fraction of trajectories reaching a prescribed minimum separation of 3 A. The calculated capture cross sections for a rotational temperature of 77 K suggest large reaction cross sections in 80 K experiments for the large dipole-moment target, methyl cyanide.

Dugan, J. V., Jr.

Integrated Carbon Capture and Propane Oxidative Dehydrogenation for Olefins Production under Isothermal Conditions over Cr₂O₃-ZSM-5/CaO-CaZrO₃ Reactive Capture Materials

Converting captured CO₂ into fuels and marketable chemicals using bifunctional materials (BFMs) represents a promising sustainable solution. In this study, a BFM composed of a Cr₂O₃/ZSM-5 catalyst and a CaO-CaZrO₃ sorbent was developed and tested for the integrated CO₂-oxidative dehydrogenation of propane (CO₂-ODHP) in a fixed bed reactor. The CaO-CaZrO₃ sorbent, prepared using the citrate sol-gel method, demonstrated high CO₂ adsorption capacity and improved cyclic stability compared to pure CaO. The BFM achieved 23.5% propane conversion, 52.5% propylene selectivity, and 68.7% olefin selectivity at isothermal adsorption-reaction conditions (630-630 °C). Overall, this study provides insights into enhancing CO2 adsorption and developing materials for integrated CO2 capture and conversion.

Baamran, Khaled

Trajectory-capture cell instrumentation for measurement of dust particle mass, velocity and trajectory, and particle capture

The development of the polyvinylidene fluoride (PVDF) dust detector for space missions--such as the Halley Comet Missions where the impact velocity was very high as well as for missions where the impact velocity is low was extended to include: (1) the capability for impact position determination - i.e., x,y coordinate of impact; and (2) the capability for particle velocity determination using two thin PVDF sensors spaced a given distance apart - i.e., by time-of-flight. These developments have led to space flight instrumentation for recovery-type missions, which will measure the masses (sizes), fluxes and trajectories of incoming dust particles and will capture the dust material in a form suitable for later Earth-based laboratory measurements. These laboratory measurements would determine the elemental, isotopic and mineralogical properties of the captured dust and relate these to possible sources of the dust material (i.e., comets, asteroids), using the trajectory information. The instrumentation described here has the unique advantages of providing both orbital characteristics and physical and chemical properties--as well as possible origin--of incoming dust.

Simpson, J. A.

Probabilistic Approach to Assessing Capture System Performance Margin in Mars Sample Return's Capture, Containment, and Return System

In the aerospace industry, there are standard design principles and/or rule-of-thumb targets that define healthy levels of margins required at each developmental milestone for traditional metrics, such as mass, thermal, and power margins. When the technical resource is “non-traditional,” in the sense that guiding margin principles are non-existent, systems engineering processes are required to internally generate performance targets and methodologies to assess the system against the derived targets. This paper presents a probabilistic approach for assessing complex time-critical operations which applies global sensitivity analyses to identify input parameters that should drive the design. This approach is used to design a critical payload required for the Mars Sample Return campaign aiming at bringing back rock and atmospheric samples from Mars.

Performance Margins

Small Particles Intact Capture Experiment (SPICE)

The Small Particles Intact Capture Experiment (SPICE) will develop technologies and engineering techniques necessary to capture nearly intact, uncontaminated cosmic and interplanetary dust particles (IDP's). Successful capture of such particles will benefit the exobiology and planetary science communities by providing particulate samples that may have survived unaltered since the formation of the solar system. Characterization of these particles may contribute fundamental data to our knowledge of how these particles could have formed into our planet Earth and, perhaps, contributed to the beginnings of life. The term 'uncontaminated' means that captured cosmic and IDP particles are free of organic contamination from the capture process and the term 'nearly intact capture' means that their chemical and elemental components are not materially altered during capture. The key to capturing cosmic and IDP particles that are organic-contamination free and nearly intact is the capture medium. Initial screening of capture media included organic foams, multiple thin foil layers, and aerogel (a silica gel); but, with the exception of aerogel, the requirements of no contamination or nearly intact capture were not met. To ensure no contamination of particles in the capture process, high-purity aerogel was chosen. High-purity aerogel results in high clarity (visual clearness), a useful quality in detection and recovery of embedded captured particles from the aerogel. P. Tsou at the Jet Propulsion Laboratory (JPL) originally described the use of aerogel for this purpose and reported laboratory test results. He has flown aerogel as a 'GAS-can Lid' payload on STS-47 and is evaluating the results. The Timeband Capture Cell Experiment (TICCE), a Eureca 1 experiment, is also flying aerogel and is scheduled for recovery in late April.

Nishioka, Ken-Ji