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DOE OSTI2023

Hanford Waste Treatment Plant Effluent Management Facility Stack Effluent Monitoring: Sampling Probe Location Qualification Evaluation

The Hanford Tank Waste Treatment and Immobilization Plant Effluent Management Facility (EMF) stack monitor location was qualified using a combination of scale model stacks to mitigate the risk of identifying that the sampling location does not meet the qualification criteria on the full-scale stack. The LV-S1 scale model stack was used as a baseline, augmented by the LB-S1 and LV-S2 scale model stacks to address the Direct Feed Low Activity Waste Effluent Management Facility Vessel Vent Process (DVP) injection into the main Active Confinement Ventilation (ACV) system duct. As required by the American National Standards Institute/Health Physics Society (ANSI/HPS) N13.1-1999 standard, the scale model and its sampling locations were geometrically similar to the actual stack, and the Reynolds numbers for both the actual and model stacks were >10,000. An additional criterion is that the product of the hydraulic diameter and mean velocity (DV) of the full-scale stack must be between 1/6 DV and 6 DV of the scale model stack tests. The LV-S1, LB-S1, and LV-S2 scale model stack tests have met the criteria of the ANSI/HPS N13.1-1999 standard to demonstrate the stack sampling locations are well mixed. Verification tests of the EMF stack were performed at normal operating conditions. The minimum 1/6 DV value and the maximum 6 DV value from the scale model testing determine the range of stack flow rates for which the full-scale stack may be operated while remaining in compliance with the stack verification criterion. A practical range for the full-scale stack qualification uses the average DV through 6 DV from the scale model tests to compute the corresponding flow rates. Table S1 lists the operating flow rate along with the average and maximum qualified stack flow rate based on the LV-S1 scale model DV values. The operating flow is below the maximum qualified stack flow, which means that the scale model test results are acceptable for stack qualification. The remaining criteria for the stack verification to be considered valid involve the flow angle and velocity uniformity results. First, the flow angle at the full-scale stack must be ≤20°. Second, the velocity uniformity at the full-scale stack must be ≤20% coefficient of variance (COV). Finally, the velocity uniformity results for the actual and scale model stack tests must agree within 5% COV. These criteria were met through the full-scale stack test at the EMF. Flow angle results were <5°; all flow angle results were within the ≤20° criterion. The velocity uniformity results for each test condition ranged between 2.2% COV and 4.3% COV, all of which were within the range of the target % COV values from the scale model tests on the LV-S1, LB-S1, and LV S2 scale models. Based on these stack verification test results, the EMF filtered exhaust stack sampling location meets the qualification criteria provided in the ANSI/HPS N13.1-1999 standard for all planned fan operating configurations. This includes each combination of ACV fans with DVP exhausters. Further changes to the system configuration or operating conditions that are outside the qualified flow rates described in this report may require additional tests or analyses to determine compliance with the standard.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2021

Parameter dependencies of the experimental nitrogen concentration required for detachment on ASDEX Upgrade and JET

While current tokamak experiments are beginning to use real-time feedback control systems to manage the plasma exhaust, future tokamaks still require validation of theoretical models used to predict the threshold impurity concentration required to sufficiently reduce the power and particle fluxes to the divertor. This work exploits new spectroscopic measurements of the divertor nitrogen concentration, c n , in partially detached N 2 -seeded H-mode plasmas on ASDEX Upgrade (AUG) and JET with the ITER-Like Wall (JET-ILW) to test the parameter dependencies of the power flowing to the outer divertor, P div,outer , and the separatrix electron density, n e.sep . A least-squares regression of the AUG measurements demonstrates that the threshold c n required for detachment scales as $c_n∝P^{1.19±0.32}_{div,outer}n^{-2.77±0.36}_{e,sep}$. This scaling of n e,sep is also consistent with the measurements from JET which, at constant P div,outer , show $c_n∝n^{-2.43±0.27}_{e,sep}$. The dependencies of P div,outer and n e.sep is demonstrated over at least a factor of two change in both parameters and indicates a stronger dependence on n e.sep in comparison to the Lengyel model, which could be due to the assumption in this model that the heat flux channel width is independent of density. This first assessment of detachment scaling with impurity seeding highlights the need for further analysis of the systematic uncertainties of the measurement and more consistent scenarios from more tokamaks to investigate the machine size scaling.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2024

Flowing plasma rearrangement in the presence of static perturbing fields

Charged particles interacting with electromagnetic waves have a portion of their energy tied up in wave-driven oscillations. When these waves are localized to the exhaust of linear magnetic confinement systems, this ponderomotive effect can be utilized to enhance particle confinement. The same effect can be derived for particles moving via an E×B drift into a region of a static perturbation to the electromagnetic fields which has a large wave vector component in the direction of the motion. In this work, we use a simplified slab model to self-consistently solve for the electromagnetic fields within the fluid flowing plasma of a static flute-like (k∥=0) perturbation and evaluate the resulting ponderomotive potential. We find that two types of perturbations can exist within the flowing plasma, which are an O wave and an X wave in the frame moving with the fluid. In the case of tenuous plasma, these perturbations are magnetostatic or electrostatic multipole-analog perpendicular to the guiding magnetic field in the lab frame, respectfully. For denser plasmas, the O wave-like perturbation is screened at the electron skin depth scale, and the X wave-like perturbation is a combination of a similar perpendicular electric perturbation and parallel magnetic perturbation. The ponderomotive potential generated in the X wave-like case is gyrofrequency-dependent and can be used as either potential barriers or potential wells, depending on the direction of the flow velocity.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2023

Building Technologies Office 03.02.02.38 Milestone Report—Compressor Technology Development for Refrigerants with <150 Global Warming Potential

The major purpose of this project is to enable the development of compressors specifically designed for compatibility with low–global warming potential (GWP) refrigerants (with GWP values below 150). These compressors are intended for applications in residential and light commercial air-conditioning and heat pump systems. This report contains an exhaustive review of the existing literature with the intention of discerning the most efficacious methodologies currently in use for compressor modeling. This fundamental stage was designed to foster a comprehensive understanding of the intricate dynamics and mechanics of compressors. As a result, a model (PDSim) was selected to simulate scroll, rotary and linear compressor technologies.

42 ENGINEERING↗

DOE OSTI2024

NSTX-U liquid metal core-edge facility (LMCE)

NSTX-U/LMCE will provide a unique and world-leading research facility to address the primary challenge to delivering economic and timely magnetic fusion energy, namely the need to develop a power and particle exhaust and first-wall system that can withstand very high edge heat fluxes, maximize energy confinement, and avoid the production of large masses of solid eroded first-wall material. The NSTX-U/LMCE facility will assess the ability of liquid metals (LMs) – especially liquid lithium – to provide a new boundary condition for magnetic fusion systems, to extend the lifetime of the plasma facing components (PFCs) and improve core plasma confinement. Such capability is needed to establish the basis for next-step fusion facilities including fusion pilot plants, and to maintain U.S. world leadership in core-edge integration research. NSTX-U/LMCE will leverage the ability to generate very high divertor perpendicular heat flux q⊥ ~ 100MW/m 2 , extensive diagnostics, and liquid-metal-applicable infrastructure of NSTX-U. NSTX-U/LMCE will provide access to a high-confinement plasma core with majority self-driven plasma current, the flexibility to test a range of liquid metal divertor concepts, access to a range of separatrix collisionalities (from high to very low), and the ability to controllably vary the first-wall temperature to vary the plasma- wall interaction physics on liquid lithium components. Further, NSTX-U/LMCE will utilize more reactor-relevant high-Z refractory-metal PFC substrates. With these capabilities the NSTX-U/LMCE facility will explore the full continuum of core-edge solutions ranging from high core radiated power, to conditions with radiative losses concentrated in the scrape-off layer (SOL), and ultimately low recycling conditions. The low collisionality SOL that may be accessible in the low recycling regime is relatively unexplored and will require a kinetic treatment of the edge, which can be addressed theoretically, and with experiments in LTX-β. Additional smaller-scale preparatory R&D facilities will be required to reduce the risk of premature technical/engineering failure of liquid metal systems implemented in NSTX-U. The NSTX-U/LMCE facility aligns very well with recommendations in the FESAC Long-Range Plan and NASEM Pilot Plant reports and the Bold Decadal Vision, will be unique in the world program throughout the next decade, and is garnering private company interest in utilizing NSTX-U/LMCE for development of LM PFCs.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2022

Integrated transient modeling of gas turbine and sCO2 power cycle for exhaust heat recovery application

For distributed generation installations, the transient response of the power generation system is critical to meet power quality (voltage and frequency) requirements. Transient models for gas turbine and supercritical carbon dioxide (sCO2) power cycle were integrated for an exhaust heat recovery bottoming cycle system for a distributed generation application. The transient model for the SGT-750 Siemens gas turbine was a ‘black-box’ functional mockup interface (FMI) model developed by Siemens Industrial Turbomachinery in $Finsp\mathring{a}ng$, Sweden. The SGT-750 is a twin-shaft gas turbine that produces 40 MW electricity with an efficiency of about 40% at ISO conditions. At 100% gas turbine throttle (load), the SGT-750 has average exhaust conditions of 114.6 kg/s and 469.8 °C.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2024

Demonstration of the carbon capture with building make-up air unit

Building-integrated carbon capture technology has the potential to reduce the cost of CO 2 capture while improving indoor air quality (IAQ). To promote the adoption of CO 2 capture in a building environment, this study investigated the possibility of integrating carbon capture technology with an existing rooftop make-up air unit (MAU) system to trap CO 2 . Here, in this study, a modular compact CO 2 capture system containing amine-functionalized polymer fibers was examined. The system, which was installed at the exhaust of the MAU, captures CO 2 before it leaves the building to enter the atmosphere as a greenhouse gas. The demonstrated average amount of CO 2 captured was 1.1–1.4 mmol/g of adsorbent material. Techno-economic analysis (TEA) was further performed on the CO 2 capture system, considering material costs, energy costs, as well as transportation and regeneration costs. These results were then used to estimate the levelized cost per ton CO 2 captured (LCOC). To achieve LCOC below $\$$100/t-CO 2 , adsorbents should have working capacities of 4.9 t and 3 t-CO 2 /year for 5 years and 10 years of operation, respectively. In summary, this study highlights a viable path toward the decarbonization of the commercial buildings sector and provides quantitative performance and economic insight on the suitability of building-integrated carbon capture technology.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2020

Efficiency of Room Air Cleaners for Removal of Bioaerosols From Ambient Air

The COVID-19 pandemic necessitated the evaluation of commercial air purification units to protect worker safety in indoor spaces. This project evaluated the efficacy of commercial off-the-shelf air purification systems that utilize electrostatic precipitation for the collection and removal of particulates (including bioaerosols) from ambient air. An aerosol mist containing Escherichia coli (E. coli) and bacteriophage surrogate virus, MS2, was produced using a nebulizer and delivered to the front intake of the commercial system with the ionizer ON and OFF. Removal efficiency was evaluated by colony/plaque formation assays using a small agar plate (60 X 15 mm) to passively collect E. coli and MS2 exhausting from the electrostatic precipitation cell. The system was determined to remove 98-99% of the microorganism introduced to the system. Testing was performed with all pre- and post-electrostatic cell filters removed so further removal is anticipated.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2020

Tracking Radioactive Isotopes in HVAC and Application for Hot Cell Analyses - 20155

In recent years, the surge in the number of isotope production facilities under design has increased the need to analyze isotope migration in facility Heating, Ventilation, and Air Conditioning (HVAC) during normal operations and accident scenarios. These facilities are used to produce isotopes for medical, security, and industrial applications and as such are subject to license and regulatory requirements 10CFR20, 10CFR30, 10CFR50, and 10CFR70. GOTHIC, a general-purpose thermal-hydraulics software package, includes the ability to model isotopic tracers, radioactive decay and isotope migration as well as HEPA and charcoal filters for isotope retention. A GOTHIC model was developed by Zachry Nuclear Engineering (ZNE) to examine the effect of negative room pressure, HEPA filtration, and HVAC fluctuations on radiation areas, hot cells and gloveboxes. Radioactive tracers were used to simulate the concentration of spills within contaminated areas, track the migration of isotopes of interest, and determine the isotopic retention and buildup on facility HEPA filters. A variety of isotopes with concern to dose (e.g., Kr-85, Sr-90, I-131, etc.), including their decay and progeny, are included in the analysis. Negative pressures are maintained in the regions of interest by a representative central HVAC system equipped with a volumetric fan that exhausts to the environment after a series of isolation valves and HEPA filters. GOTHIC is an industry trusted tool for providing engineering solutions for a variety of applications, including fission product tracking, aerosol and particulate transport and ventilation assessments. The software provides an integrated analysis environment that includes a graphical user interface (GUI) for constructing analysis models, a numerical solver that includes parallel processing capabilities and a post-processor for evaluating simulation results. It solves the conservation equations for mass, momentum and energy for multicomponent, multi-phase flow in lumped parameter and multi-dimensional geometries (1, 2, or full 3D), including the effects of turbulence, diffusion and buoyancy. It has been developed and maintained under a Quality Assurance program in compliance with the requirements of 10CFR50 Appendix B and applicable portions of ASME NQA-1 since 1995. GOTHIC has been used for assessing both forced and natural convection conditions for a wide range of applications, including: - Tracking concentration of hazardous gases and chemicals for habitability and safety assessments - Determining ventilation and filtration requirements and optimizing location and arrangement of these systems - Room heat-up, including diverse and Flexible coping strategies for Extended Loss of AC Power (FLEX/ELAP) - Equipment Qualification (EQ) A distinctive feature of GOTHIC is the ability to track many different fields/substances in a simulation, including user defined tracer elements, in the liquid, vapor and droplet fields as well as surfaces and filters. This capability allows GOTHIC to model fission product transport and release or the removal of particulates or harmful toxins from exhaust gases using a spray scrubber or other types of filtration systems. GOTHIC also includes models for engineered equipment, such as fans, filters, charcoal filters, dryers/demisters, dampers, etc. The aerosols and other filtered material are removed or accumulated in these components. The range of aerosol and radiological applications that GOTHIC has been used for includes: - Source Term: Primary Coolant (Equilibrium) Activity; Non-Water Coolant Source/Leakage. - Conditions for Iodine Re-evolution: Sump/Suppression Pool Conditions and pH; - RWST Conditions and pH. - Isotope Removal Mechanisms: Containment Sprayed and Unsprayed Region Mixing; Charcoal Filter Heating due to Iodine decay. - Radionuclide Transport and Decay: Post-LOCA Release in containment; Transport between connected Compartments and vent systems; Groundwater transport of radionuclides. - Non-Newtonian Fluid modeling for sludge, waste tanks, etc. ADAMS ML071581053 (titled 'Best Practice Guidelines for the use of CFD in Nuclear Reactor Safety Applications') poses guidelines for applying single phase CFD codes in nuclear reactor safety problems and GOTHIC is listed as a 'tool for 3D flows' and 'dispersal and deposition of radionuclides.' The Nuclear Quality Assurance (NQA) pedigree of GOTHIC is an important aspect for applications in the nuclear industry. The fundamental tracer models (convective transport, molecular and turbulent diffusion, removal mechanisms, etc.) have been verified using analytical solutions and validated against applicable separate effects tests. Also, GOTHIC has been benchmarked to many integrated effects tests, including Phebus FP (Fission Product). GOTHIC gives good agreement for the buildup and decay of fission products in Phebus Test 3. The model developed by ZNE demonstrates GOTHIC's applicability and acceptability for use in analyzing the migration and retention of radioactive isotopes and their progeny in normal operation and accident scenario analyses for isotope production facilities, hot cells, and gloveboxes. The tracer activities calculated by GOTHIC can then be used in downstream radiation transport and shielding codes like RADTRAD-NAI{sup C}, MCNP{sup R}, and MicroShield{sup R} to determine on-site and of-site doses. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

CO 2 coverage on Pd catalysts accelerates oxygen removal in oxy-combustion systems

Oxy-combustion systems result in enriched CO 2 in exhaust gases; however, the utilization of the concentrated CO 2 stream from oxy-combustion is limited by remnant O 2 . CH 4 oxidation using Pd catalysts has been found to have high O 2 -removal efficiency. Here, in this study, the effect of excess CO 2 in the feed stream on O 2 removal with CH 4 oxidation is investigated by combining experimental and theoretical approaches. Experimental results reveal complete CH 4 oxidation without any side-products, and a monotonic increase in the rate of CO 2 generation with an increase in CO 2 concentration in the feed stream. Density-functional theory calculations show that high surface coverage of CO 2 on Pd leads to a reduction in the activation energy for the initial dissociation of CH 4 into CH 3 and H, and also the subsequent oxidation reactions. A CO 2 -rich environment in oxy-combustion systems is therefore beneficial for the reduction of oxygen in exhaust gases.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Integrated heat and energy recovery ventilator system

A heat recovery ventilator (HRV) and/or energy recovery ventilator (ERV) that integrates with a residential capacity air handling unit (AHU) is embodied in a small footprint HRV or ERV unit that connects directly to the return side of an AHU and to outdoor air inlet and exhaust ducts. The ventilator includes a control system incorporating a processor and sensors that control the operation of the system to provide desired ventilation flow rates under varying conditions.

Puttagunta, Srikanth↗

DOE OSTI2022

Iodine Removal in the DFLAW Flow-Sheet

In support of the WTP project, off-gas system and regulatory testing has been conducted previously on the DM1200 pilot melter equipped with a prototypical off-gas system installed at The Catholic University of America’s Vitreous State Laboratory (VSL). During the regulatory tests, an AC-S test bed filled with Kombisorb BAT 37 was included in the prototypical off-gas system and evaluated for response to HLW and LAW exhaust streams. Offline testing and small-scale testing of that media were also conducted. Testing demonstrated that a temperature rise occurred in the activated carbon media when water vapor was first introduced to virgin Kombisorb BAT 37, in response to high nitrogen oxide concentrations, and in response to the presence of organic compounds. Conditioning of the test bed by gradually increasing the NOx concentration prior to the introduction of organics was found to be an important operational strategy for preventing larger temperature excursions. However, no mercury was present in the exhaust stream during DM1200 testing and therefore comparable test data for mercury removal efficiency or temperature response of the carbon media in the presence of mercury were not collected in the DM1200 tests. In view of the need for data on mercury removal performance, BNI contracted with Atkins and the VSL to install and operate a suitable test system at VSL to collect the required data. That testing was designed to assess the performance of Kombisorb BAT-37 and the guard bed material, Sofnolime RG, for simulated melter exhaust streams that contain the highest concentrations of mercury, nitrogen oxides, acid gases, and organic compounds expected in WTP LAW melter exhaust. During shakedown testing with the new system, however, it became evident that a number of issues with Sofnolime RG as the guard bed material would render it unsuitable for this application. BNI subsequently determined that the guard bed was redundant for removal of acid gases since they could be adequately removed by the SBS and WESP. However, since the guard bed material was also credited with significant iodine removal , there was a need for a replacement material that would adequately perform that role. BNI identified several candidate media but performance data in gas compositions that are representative of the WTP LAW off-gas were not available. Accordingly, there was a need to test and evaluate the performance of these candidate media prior to performing the originally-planned tests. To that end, small scale tests were conducted to assess the performance of various adsorbents in simulated melter exhaust streams that contain mercury, iodine, nitrogen oxides, acid gases, and acetonitrile, which are expected to be present in WTP LAW melter exhaust.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Natural Gas Combined Cycle (NGCC) Power Plants with Carbon Capture and Exhaust Gas Recycle (EGR)

The purpose of this study is to determine the cost and performance of natural gas combined cycle (NGCC) power plants using state-of-the-art gas turbines with post combustion carbon capture and recycle streams designed to increase the CO 2 concentration in the inlet to the capture system. Increasing the inlet CO 2 concentration by exhaust gas recycle (EGR) is expected to improve the efficiency of the capture system and reduce its costs. Primary results indicate that adding EGR to NGCC plants with CO 2 capture results in minimal improvement to the cost of electricity. The addition of 50 percent EGR in NGCC plants with CO 2 capture reduces the LCOE by 2 percent over the LCOE of the same design without EGR as reference. Including the EGR ductwork and cooler in a greenfield plant design could still be prudent since there is some cost advantage to EGR and it would allow more flexibility for taking advantage of future improvements in the technology.

20 FOSSIL-FUELED POWER PLANTS↗

DOE OSTI2021

Fuel cell system having enhanced CO2 capture

A carbon dioxide capture system for removing carbon dioxide from a flue gas produced by a combustion power plant. The system includes an electrolyzer cell configured to receive a flue gas comprising carbon dioxide and output a first exhaust stream comprising an enriched flue gas comprising carbon dioxide. The system further includes a fuel cell configured to receive the first exhaust stream and output a second exhaust stream comprising carbon dioxide. The second exhaust stream contains a higher concentration of carbon dioxide than the first exhaust stream.

Jahnke, Fred C.↗

DOE OSTI2022

Optimization of thermal barrier coating performance and durability over a drive cycle

A methodology to thermo-mechanically optimize a piston thermal barrier coating over a full drive cycle was established. The optimization objective was to minimize the heat transfer to the engine wall while maintaining structural integrity of the coating. Over 800 candidate materials were investigated and the optimization required more than one million non-road transient drive cycle calculations; real materials were investigated to ensure a realizable result and the existence of thermal and mechanical properties. High computational efficiency was achieved using a recently developed analytical heat transfer technique for multilayer engine walls. An uncoupled approach was utilized for the optimization, wherein the gas temperature and heat transfer coefficient profiles from a fully coupled and calibrated baseline model over the 20-min drive cycle were employed. The coating/piston interface temperature was constrained to be below the maximum piston service temperature limit. The durability was assessed using a recently developed analytical coating delamination framework for engine in-cylinder coatings based on the energy release rate when a crack forms. Results are presented for a mechanically unconstrained optimization and for cases constrained to three fixed levels of drive-cycle maximum energy release rate, and also constrained by the individual material’s toughness. The best-performing coating materials identified were verified using the fully coupled system-level model, which compared well to the uncoupled predictions. A study on the effect of adding a sealing layer to some high-performing, but porous, coatings showed a reduction in fuel consumption benefit and an increased exhaust temperature over the cycle, but the system still outperformed the uncoated case. The results of the study elucidate the importance of including engine performance and mechanical failure considerations in thermal barrier coating design.

Engineering↗

DOE OSTI2025

Double-null power-sharing dynamics in MAST-U

Maintaining an effective double-null (DN) configuration is expected to be challenging in reactor-scale tokamak devices. As divertor power-sharing is closely linked to the magnetic topology, even minor variations can lead to fast power-sharing fluctuations which exacerbate the already daunting exhaust challenge. While the static aspects of DN power-sharing have been extensively studied across various devices, this paper presents the first detailed investigation of its dynamic behaviour. We employ dedicated H-mode experiments in MAST-U, in Super-X divertor configuration, featuring perturbation frequencies up to 200 Hz. Our results clearly show no significant dynamic damping of the power-sharing within this frequency range: the divertor responds equally to both fast and slow perturbations. Moreover, the dynamic response also aligns with quasi-static results from slow ramps, implying that static power-sharing models remain valid even for fast fluctuations. Occasionally, some deviations from the otherwise mainly linear behaviour are observed, alongside notable scatter and asymmetries between upwards and downwards trajectories. These observations are likely linked to changes in core conditions, though the underlying mechanisms remain unclear and require further study.

divertor↗

DOE OSTI2026

Carbon Tetrachloride Degradation Results for 200-ZP-1 Operable Unit

Carbon tetrachloride (CT) contamination in the 200-ZP-1 Operable Unit (OU) at the Hanford Site originated from large-volume discharges to the subsurface during plutonium production operations between 1955 and 1973. Contamination migrated through more than 70 meters of unsaturated sediment to reach the underlying unconfined aquifer, where it persists as a large and complex groundwater plume. The 200-ZP-1 OU Record of Decision (ROD) requires that groundwater CT concentrations be reduced to 3.4 µg/L within 125 years. Current groundwater modeling projections estimate that the existing pump-and-treat, even when combined with monitored natural attenuation (specifically hydrolysis), will not achieve this target within the designated timeframe. A fundamental contributor to this shortfall is the extremely slow rate of CT hydrolysis under Hanford aquifer conditions, which has been estimated to have a half-life of 630 years. If faster-acting biotic and abiotic degradation processes are operating within the aquifer, their contribution to CT mass reduction could have a meaningful impact. However, site-specific measurements of these processes and their rates have not previously been performed. This report documents the results of a two-phase laboratory investigation designed to characterize and quantify the capacity of site-specific 200-ZP-1 OU sediments and groundwater to support natural attenuation of CT through biotic and abiotic pathways. In this context, degradation capacity is defined as the intrinsic potential of the subsurface matrix to transform CT under optimized, controlled conditions. System capacity is evaluated in two ways: (1) as rate-limited capacity, which establishes the maximum kinetic velocity of CT transformation and is measured using half-lives and first order rate constants; and (2) as mass limited capacity, which defines the total contaminant mass the batch experimental system can degrade before reactants are exhausted, representing the maximum amount of contaminant the microbial community and reactive mineral phases can transform under the experimental conditions.

abiotic degradation↗

DOE OSTI2021

Systems and methods for cylinder deactivation in dedicated EGR engine

Systems, apparatus, and methods are disclosed that include a divided exhaust engine with at least one primary exhaust gas recirculation (EGR) cylinder and a plurality of non-primary EGR cylinders. The systems, apparatus and methods control the EGR fraction by deactivation of one or more of the cylinders.

Desai, Akash S.↗