Compact Reactor Research Articles

Compact Carbon-Based Membrane Reactors for the Intensified Anaerobic Decolorization of Dye Effluents.

Carbon-based membranes integrated with anaerobic biodegradation are presented as a unique wastewater treatment approach to deal with dye effluents. This study explores the scope of ceramic-supported carbon membrane bioreactors (B-CSCM) and ceramic-supported graphene oxide membrane bioreactors (B-CSGOM) to decolorize azo dye mixtures (ADM) and other dyes. The mixture was prepared using an equimolar composition of monoazo Acid Orange 7, diazo Reactive Black 5, and triazo Direct Blue 71 dye aqueous solution. Afterwards, as in the ADM experiment, both compact units were investigated for their ability in the biodecolorization of Methylene Blue (MB) and Rhodamine B (RhB) dye solutions, which do not belong to the azo family. The obtained outcomes revealed that the conductive surface of the graphene oxide (GO) membrane resulted in a more efficient and higher color removal of all dye solutions than B-CSCM under a wide feed concentration and permeate flux ranges. The maximum color removal at low feed concentration (50 mg·L−1) and permeate flux (0.05 L·m−2·h−1) was 96% for ADM, 98% for MB and 94% for RhB, whereas it was 89%, 94% and 66%, respectively, for B-CSCM. This suggests that the robust, cost-effective, efficient nanostructures of B-CSGOM can successfully remove diverse azo dye solutions from wastewater better than the B-CSCM does.

Boron‐containing nonwoven polymeric nanofiber mats as neutron shields in compact nuclear fusion reactors

Composite materials that contain thermally and chemically stable boron compounds are attractive candidates for applications that require high neutron absorption due to the large neutron absorption cross-section of boron. Electrospun polymer nanofibers have a unique volume-to-surface area, incorporating carbon and hydrogen atoms in their molecular structure that could moderate and thermalize incident neutrons. Nonwoven nanofibers could in turn reduce neutron scattering and increase neutron absorption by providing large surfaces and better atom economy in the shield materials. The expected high absorption will result from improved neutron interaction with high neutron absorbance hydrogen, carbon, and boron atoms in the nanofibers through increased specific surface area and atom economy. In this work, elemental boron-doped PVA polymeric nanofibers are produced for the first time to date for the application of neutron shielding. With the increasing demand for nuclear power generation and radiation therapies in medicine, the need for producing lightweight and flexible materials that could replace the traditional heavy metal/metal carbide-based shields is vital. Similarly, the need for flexible materials that could shield neutrons is also becoming critical for aerospace applications. The effect of boron content on the quality of fibers and neutron shielding capacity is evaluated by using an Am-Be neutron source. Characterization studies of produced nanofibers were carried out by SEM, TGA, FT-IR, and XPS analyses. Results have shown that PVA-based nanofibers doped with wt% 0.1 to 0.5 boron, having fiber diameter distribution between 60 and 330 nm range, could absorb up to 6% of neutron flux.

The CANDLE burnup strategy applied to small modular pressurized water reactor loading with fully ceramic microencapsulated fuel

Abstract For post-Fukushima nuclear power plants, there has been interested in accident-tolerant fuel (ATF) since it has better tolerant in the event of a severe accident. The fully ceramic microencapsulated (FCM) fuel is one kind of the ATF materials. In this study, the small modular pressurized water reactor (PWR) loading with FCM fuels was investigated, and the modified Constant Axial shape of Neutron flux, nuclide number densities and power shape During Life of Energy producing reactor (CANDLE) burnup strategy was successfully applied to such compact reactor core. To obtain ideal CANDLE shape, it’s necessary to set the infinity or enough length of the core height, but that is impossible for small compact core setting infinity or enough length of the core height. Due to the compact and finite core, the equilibrium state can only be maintained short periods and is not obvious, other than infinitely long active core to reach the long equilibrium state for ideal CANDLE. Consequently, the modified CANDLE shape would be presented. The approximate characteristics of CANDLE burnup are observed in the finite and compact core, and the power density and fuel burnup are selected as main characteristic of modified CANDLE burnup. In this study, firstly, lots of optimization schemes were discussed, and one of optimization schemes was chosen at last to demonstrate the modified CANDLE burnup strategy. Secondly, for chosen compact small rector core, the modified CANDLE burnup strategy is applied and presented. Consequently, the new characteristics of this reactor core can be discovered both in ignition region and in fertile region. The results show that application of CANDLE burnup strategy to small modular PWR loading with FCM fuels suppresses the excess reactivity effectively and reduces the risk of small PWR reactivity-induced accidents during the whole core life, which makes the reactor control more safety and simple.

Design and Performance Investigation of a Compact Catalytic Reactor Integrated with Heat Recuperator

The catalytic combustion has the advantage of lower auto-ignition temperature and helps to expand the combustible limit of lean premixed gas. However, the intake needs to be preheated to certain temperature commonly through an independent heat exchanger. Similar to the principles of non-catalytic RTO combustion, this paper presents a similar approach whereby the combustion chamber is replaced by a catalytic combustion bed. A new catalytic reactor integrated with a heat recuperator is designed to enhance the heat recirculation effect. Using a two-dimensional computational fluid dynamics model, the performance of the reactor is studied. The reaction performances of the traditional and compact reactors are compared and analyzed. Under the same conditions, the compact reactor has better reaction performance and heat recirculation effect, which can effectively decrease the ignition temperature of feed gas. The influences of the inlet velocity, the inlet temperature, the methane concentration, and the thermal conductivity of porous media on the reaction performance of integrated catalytic reactor are studied. The results show that the inlet velocity, inlet temperature, methane concentration, and thermal conductivity of porous media materials have important effects on the reactor performance and heat recirculation effect, and the thermal conductivity of porous media materials has the most obvious influence. Moreover, the reaction performance of multiunit integrated catalytic reactor is studied. The results show that the regenerative effect of multiunit integrated catalytic reactor is further enhanced. This paper is of great significance to the recycling of low calorific value gas energy and relieving energy stress in the future.

Elaboration of a Promising Design of the HTS Conductor for the Central Solenoid of a Compact Thermonuclear Reactor TRT

The results of the preliminary development of the HTS conductor based on the VS-type design and parallel stacks for the central solenoid of the compact thermonuclear reactor TRT are presented. One of the main problems that need to be solved for the successful implementation of such projects is the creation of high-current high-temperature superconducting (HTS) conductors for Toroidal Field coils (TF) and Central Solenoid (CS) sections. The conductor must have a high engineering current density of at least 90 A/mm2. The induction of the magnetic field in the central solenoid reaches 14 T, which leads to the occurrence of large mechanical stresses due to the influence of Lorentz forces. Like many large magnets, CS has a lot of stored energy. For the safe withdrawal of stored energy from the magnet, it requires the inclusion of elements in the conductor that provide an acceptable level of electrical voltage and heating of the conductor insulation. Thus, a sufficient amount of stabilizing and reinforcing materials should be placed in the conductor. In addition, the “cable-in-conduit” type of conductor must have channels for pumping the refrigerant. Two fundamentally different versions of the conductor based on radially arranged REBCO tapes and on the basis of pre-assembled tape packages are considered. Based on the analysis of the magnetic field distribution in the conductor by finite element method, the design characteristics of the proposed conductors under various operating modes of the electromagnetic system (EMS) of the tokamak TRT was evaluated. The results of the evaluation of the current carrying capacity of the conductor and the estimation of energy losses in a changing magnetic field in comparison with known methods are also presented.

Transport phenomena in compact endothermic catalytic reactors for the production of hydrogen

Transport phenomena in compact endothermic catalytic reactors for the production of hydrogen

Application of the Analytic Hierarchy Process for selection of alternative solutions for domestic wastewater treatment

Choosing the best form of domestic sewage treatment requires analyses that allow decision-making on the ideal solutions for implementation, according to the particularities of each regionality, especially when it comes to rural and isolated areas dependent on decentralized solutions. Thus, through this study, the Analytic Hierarchy Process (AHP) was used from a data collection on simplified treatment systems existing in temperate municipalities without a dry season, to evaluate priority systems in different scenarios considering environmental, social, and technical-economic indicators. Among the results for the scenarios performed, the compact upflow anaerobic reactor, the septic tank and anaerobic filter, and the septic tank and built-in flooded system of vertical subsurface flow were the solutions that proved to be the most indicated following the indicators used and the existing information. It is noteworthy that the results refer to the study area in question, and new applications of the method are needed in different climatic regions. From the application of the methodology, the AHP tool indicated that it is a viable method to assist in decision-making regarding the selection of sewage treatment systems in rural areas, which, being tied to municipal planning in basic sanitation, assists in the optimization of existing resources. The sensitivity of the method showed the importance of its application with data collected on site, in addition to the incorporation of public and experts opinions in the contribution of the degree of importance of the criteria and indicators used.

Confinement in electron heated plasmas in Wendelstein 7-X and ASDEX Upgrade; the necessity to control turbulent transport

In electron (cyclotron) heated plasmas, in both ASDEX Upgrade (L-mode) and Wendelstein 7-X, clamping of the ion temperature occurs at T i ∼ 1.5 keV independent of magnetic configuration. The ions in such plasmas are heated through the energy exchange power as , which offers a broad ion heating profile, similar to that offered by alpha heating in future thermonuclear fusion reactors. However, the predominant electron heating may put an additional constraint on the ion heat transport, as the ratio T e/T i > 1 can exacerbates ITG/TEM core turbulence. Therefore, in practical terms the strongly ‘stiff’ core transport translates into T i-clamping in electron heated plasmas. Due to this clamping, electron heated L-mode scenarios, with standard gas fueling, in either tokamaks or stellarators may struggle to reach high normalized ion temperature gradients required in a compact fusion reactor. The comparison shows that core heat transport in neoclassically optimized stellarators is driven by the same mechanisms as in tokamaks. The absence of a strong H-mode temperature edge pedestal in stellarators, sofar (which, like in tokamaks, could lift the clamped temperature-gradients in the core), puts a strong requirement on reliable and sustainable core turbulence suppression techniques in stellarators.

The Stereo search for a sterile neutrino at the ILL reactor with full data sample

During the last decades, several parameters describing the neutrino oscillation phenomenon have been characterized thanks to reactor neutrino experiments, in particular the precise measurement of the last-to-be-measured mixing angle θ 13. Following a reactor antineutrino flux re-estimation in 2011, a 6% deficit between observed and predicted reactor antineutrino fluxes, known as the Reactor Antineutrino Anomaly, has been observed. The Reactor Antineutrino Anomaly could be explained by an oscillation toward an additional non-interacting, (thus “sterile”) neutrino. The parameters that best explain the RAA are a mixing angle value of sin2 (2θnew ) = 0.17 and a mass splitting value of . Additionally, a discrepancy between the measured and predicted antineutrino energy spectrum taking the form of an excess of events around 5 MeV has been observed by several reactor neutrino experiments. This discrepancy has yet to be fully understood but could be caused by incorrect predictions of the neutrino spectra. The STEREO experiment, located at Institut Laue-Langevin in Grenoble (France), was designed to test the above mentioned oscillation hypothesis independently of shape and rate predictions. The segmented detector, located at ∼10 m of a compact reactor core, allows for a measurement of the antineutrino energy spectrum at various baselines, sensitive to the oscillation toward a sterile neutrino that would distort the spectrum differently at each baseline. The experiment could also help to disentangle isotopic contributions to the neutrino energy spectrum by providing a measurement of the spectrum shape and rate originating from a core with highly enriched (93%)235U. The experiment took data between November 2016 and November 2020. This talk will present the latest limits set in the oscillation parameter space with the full data sample, amounting to 334 (544) days of reactor-on (off), as well as the updated rate and spectrum shape measurements.

Computational fluid dynamics simulation of internally circulating fluidized bed reactor for dry reforming of methane

Internally circulating fluidized bed reactor (ICFB) is the reactor that combines the conventional circulating fluidized bed (CFB) reactor system, including riser, downer, loop seal and cyclones, into a single compact reactor column. The ICFB reactor column is separated into two sections (riser and downer) by baffles and is linked together via connecting ports. The solid particles are circulated in the ICFB reactor by unequal fluidizing velocities in the riser and downer sections. The solid particles in the downer section are operated with low fluidizing velocity in the bubbling fluidization regime. In the riser section, the solid particles are transferred to the downer section because of the high fluidizing velocity. In this study, the carbon dioxide reforming or dry reforming reaction of methane was investigated. Dry reforming is a reaction between carbon dioxide and methane, which are the major greenhouse gases, for producing syngas, hydrogen and carbon monoxide. The hydrodynamics and dry reforming reaction with different reactor designs were explored using two-dimensional Eulerian–Eulerian computational fluid dynamics simulation (CFD). The ICFB reactor with no elevation gas distributor, 90 cm of draft tube height, 2 cm of loop-seal length and 1 cm of gas outlet diameter gave the highest methane conversion of 15.4%. The analysis of variance (ANOVA) indicated that the length of loop-seal and the gas outlet diameter gave substantial negative and positive effects on methane conversion, respectively. The interaction between length of loop-seal and gas outlet diameter also had a significant effect on the methane conversion. Although the ICFB reactor in this study gave the methane conversion slightly lower than referenced literature conventional CFB reactor, the ICFB reactor is the reactor that can reduce construction cost and simplify complex reactor operation.

Production of Carbon Black in Turbulent Spray Flames of Coal Tar Distillates

Conventional carbon black production occurs by pyrolysis after heavy aromatic feedstock is injected into the post-combustor region of furnace black reactors. The current work examines the conversion of the coal tar distillate in turbulent spray flames to demonstrate a more compact reactor configuration. Coal tar distillates diluted in toluene is atomized and burned in a standardized flame spray synthesis configuration, known as SpraySyn. Flame conditions are characterized by thermocouple, soot pyrometry and image analysis and product particle properties are examined by TEM and Raman spectroscopy. The measured flame temperature corresponds to the range of temperatures used in the furnace black process, but the current synthesis includes oxidizing conditions and faster residence times. The resulting carbon black particles are aggregates with primary particle sizes on the small end of the carbon black size spectrum, according to analysis of TEM images. Carbon black, formed under a range of flame temperatures, show Raman spectra with features resembling typical carbon black materials. Conversion of coal tar distillate to carbon black by direct flame synthesis may be a scalable method to produce high-surface area grades without a conventional pyrolysis reactor stage.

Combined compact anaerobic reactors and lamella settlers for decentralized sewage treatment

Abstract This work presents a compact plant's development and performance evaluation for the decentralized treatment of domestic sewage. The plant was conceived and installed in a house with four residents in Vicente Pires, Federal District, Brazil. Its purpose was to remove organic matter and solids using a low-cost biological treatment process that was simple to operate. The plant was essentially anaerobic, composed of an up-flow anaerobic reactor and an anaerobic filter, both associated with lamella settlers. It was operated under real conditions and monitored for nineteen months, with removal efficiencies (calculated over the medians) of 81% for COD, 83% for BOD, 51% for Total Solids, 55% for Total Volatile Solids, 87% for Total Suspended Solids, and 100% for Settleable Solids. The plant performed adequately, with no clogging between the plates of the lamella settlers, no offensive odours, and limited amounts of sludge and scum.

Neutronic Performance of a Compact 10 MWe Nuclear Reactor with Low Enrichment (ThxU1\u2212x)N Fuel

Recent interest in compact nuclear reactors for applications in space or in remote locations drives innovation in nuclear fuel design, especially non-oxide ceramic nuclear fuels. This work details neutronic modeling designed to support the development of a new nuclear fuel concept based on a mixture of thorium and uranium nitride. A Monte Carlo N-Particle Version 6.2 (MCNP-6) model of a compact 10 MWe reactor design which incorporates (ThxU1−x)N fuel is presented. In this context, a “compact” reactor is a completely assembled reactor which may be emptied of coolant and transported by specialized commercial vehicle, deployed by a C130J aircraft, or launched into space. Core geometry, reflector barrels, and the heat exchange zones are designed to support reduction of overall reactor volume of core components while maintaining criticality with a fixed total fuel mass of 4500 kg. Dense mixed nitrides of thorium nitride (ThN) additions in uranium nitride (UN) in 5 wt.% increments between 0.05 le x le 0.5 have been considered for calculation of k_{infty } and k_{{{text{effective}}}}. ThN additions in UN results in a slight increase in the magnitude of the temperature coefficient of reactivity, which is negative by design. The isotopic distribution of the principal actinide inventory as a function of burnup, time, and initial fuel composition is presented and discussed within the context of the proliferation risk of this core design.

Novel features of the helical volumetric neutron source FFHR-b2

The compact helical fusion reactor FFHR-b2 is a multipurpose HElical Volumetric Neutron Source available as the component test facility to test the divertor and blanket systems. In the latest design, three new technologies of the high-temperature superconducting conductor, the ceramic pebble divertor, and the cartridge-type blanket are adopted. Tin-based functional liquid metals (FLMs) including lithium are considered as the working fluid for the blanket. The FLMs have multi functions of low vapor pressure, low density, low melting point, low corrosiveness, high tritium breeding ratio, and so on. The target construction cost of the FFHR-b2 has been set to 200 billion JPY. The main target of FFHR-b2 is to demonstrate the fusion gain larger than one. To achieve this in a relatively small device, the tangential neutral beam injection (NBI) heating with a moderate energy of 80 keV is adopted for the FFHR-b2. The beam-plasma fusion with 5 MW of NBI heating can produce a fusion power of 5 MW that is larger than the absorbed power of 3 MW.

Economic solution for low carbon process heat: A horizontal, compact high temperature gas reactor

In 2018, nuclear energy generated 55% of United States’ and one third of the world’s carbon free electricity, making nuclear energy a key tool in efforts to mitigate climate change before 2050. However, the current nuclear technology, light water reactors (LWRs), is limited to 300°C, so it cannot be used to decarbonize industrial process heat which accounts for 12% of US greenhouse gas emissions. High temperature gas reactors (HTGRs) can meet the high temperature demand with carbon free nuclear heat. The estimated cost of HTGRs, such as the Next Generation Nuclear Plant (NGNP), are even higher than state-of-the-art LWRs. In this paper, we expanded our nuclear cost estimating tool to include HTGRs and find that the NGNP overnight capital costs were 32% higher than an advanced LWR per unit capacity. The higher cost will naturally result in larger risk to cost overrun as recently experienced by larger LWRs in western nations. With a design-to-build mindset to minimize cost and construction risk, we introduce the horizontal, compact HTGR (HC-HTGR). The reactor core and steam generator are mounted horizontally on rails and in-line with one another, decreasing the size of the reactor building relative to the power capacity four times when compared to traditional HTGRs. The HC-HTGR reduced overnight civil structure costs by 42%, indirect costs by 38%, and total capital costs by 20% from NGNP. We discussed the required engineering of new systems for the HC-HTGR including vessel supports, the reactor cavity cooling system, and steam generator design. Finally, we estimated the fuel and operations costs of the HC-HTGR, and a survey of low-carbon industrial process heat technology showed the HC-HTGR can deliver a highly competitive levelized cost of heat in the range of $6.13–12.48/GJ.

Thermophysical Properties of Mixtures of Thorium and Uranium Nitride

The miscibility, lattice parameter, and thermophysical properties of (Th0.2U0.8)N and (Th0.5U0.5)N have been investigated. It is shown that additions of thorium nitride (ThN) to uranium nitride (UN) increases the thermophysical performance of the mixed nitride fuel form in comparison to reference UN. In the more dilute limit, additions of ThN serve as a burnable neutronic poison and reduces the change in keff over the lifecycle of the fuel. At higher concentrations, additions of ThN serve as a significant fertile source of 233U. Where appropriate, comparisons to previous work on UN + PuN mixtures are made, as this is a comparable fuel form for potential fast reactor concepts, and a suitable point of contrast in the possible design space afforded by mixed (ThxU1 − x)N fuel forms. The data from this work are the input parameters for finite element modeling of the temperature distribution in a compact reactor. The results of modeling and simulation of this core design are shown for the case of steady-state operation and during double, adjacent heat pipe failure.

Design, construction, and testing of no-insulation small subscale solenoids for compact tokamaks

Fusion energy systems studies (FESS) for next-step devices based on the most promising magnetic configurations indicate that high magnetic fields and high current density for magnet coil systems may reduce device size and lower the cost. High current density and radiation resistant fusion magnets are particularly beneficial for low cost, low aspect ratio compact reactor designs such as Fusion Nuclear Science Facility (FNSF), Fusion Pilot Plant (FPP) of low-aspect ratio spherical tokamak (ST) or compact stellarators. Unlike typical high field magnets for nuclear magnetic resonance (NMR), magnetic resonance imaging (MRI), or high energy physics research applications, neutron irradiation damage to organic insulations in the coil winding pack is a critical issue for next generation fusion reactors where orders of magnitude higher neutron fluence than those in present experimental reactors such as ITER are expected. Moreover, a high coil winding pack current density is needed for high field magnets in low cost, compact radial build next step fusion reactors. The slow current charging time, however, is an issue in fully non-insulated coils. We present the design, construction and testing of subscale Nb3Sn solenoids, up to half the diameter of the central solenoid (CS) for National Spherical Torus Experiment (NSTX), with and without inter-layer insulation for enhancing radiation resistance while improving the winding pack current density and coil performance. The major radius for the NSTX/NSTX-Upgrade (reference for compact ST) is 0.854/0.934 meter, and 4.8 meters for FNSF. The magnetic field for NSTX/NSTX-U at the plasma center is 0.6/1 Tesla and 9 Tesla for FNSF. The inner diameter of the central solenoid coil is 0.2/0.4 meter for NSTX/NSTX-U and 1.2 meters for FNSF. The current charging and discharging behavior of the prototype solenoids was investigated to quantify performance advantages of a simplified coil fabrication without error-prone vacuum pressure impregnation (VPI) for the removal of epoxy organic insulation. Scalability of the no insulation concept for fusion can be addressed via engineered coating for novel insulation on contact resistance or intra-layer no insulations. Radiation resistance and coil winding efficiency were significantly improved in the no insulation coils for next step compact fusion reactors.

Temperature field acquisition by planar laser induced fluorescence using the two-color/two-dye technique for liquid flows in a millimetric zigzag channel

The acquisition of local temperature fields in compact reactors is essential to understand the heat transfer mechanisms in these often-complex geometry devices, and to detect the presence of any dead zones where hot or cold spots can appear during implementation of reactions. In this work, thermometry by PLIF method (Planar Laser Induced Fluorescence) is implemented in a square millimetric zigzag channel of 4 mm depth. The two-color/two-dye method is used. The advantages of this technique are that it is non-intrusive and it presents a very good spatial and temporal resolution. The method is first calibrated capturing temperature fields in flowing water at constant temperature. The sensitivity of the implemented method is good, equals to 3.3%.C−1 in terms of fluorescence signal ratio. Uncertainty of 0.6% of the measured temperature is due to the noise of the acquired images, and the global uncertainty of the measurement is estimated to be lower than 3% in the temperature range of 17–60°C. The PLIF technique is then applied during heat transfer to obtain temperature fields at different positions and heights in the channel. The average temperatures measured from the local temperature fields are close to the temperature profiles calculated with a 1D heat transfer model. The obtained results show the potential of the PLIF technique to detect temperature heterogeneities in compact devices for the study and the design of intensified reactors.

Review of piston reactors for the production of chemicals

Abstract To explore options for simple, safe, and compact chemical reactors that preserve wanted metastable initial products from sequential unwanted reactions, academic and industrial researchers have tried to repurpose reciprocating piston equipment or an “engine-like” design to be used as a chemical reactor. Piston reactors offer the benefit of achieving very high temperature and pressure conditions at very short and defined residence times. Such conditions offer promise for enhanced performance for several chemical conversions. This paper provides a review of the published literature and patents in the field of piston reactors to provide an overview of the current state-of-the-art. The review covers multiple aspects of piston reactors and their applications, reactor design options and their operation, catalyst and ignition placement, tested reactions, experimental setups as well as modeling and simulation. Several research gaps are highlighted as a motivation for future research in the field. To help interested readers into the topic, basic concepts and fundamentals of piston reactors are provided.

A modeling error compensation approach for the feedback control of the nuclear reactor operation

Nuclear energy for civil applications has been a matter of renewed interest as it offers clean, safe, and reliable energy sources. A new generation of compact reactors and improved safety strategies have driven refreshed research on the design and control of nuclear plants. New results on the regulation of the power output of nuclear reactors should provide improved operation strategies oriented to reliability and safety. The present work aims to study the stability and performance of a nuclear reactor under nonlinear feedback control actions. The study considered the five states March-Leuba mathematical model of a boiling water reactor. A nonlinear feedback controller that leads to exact cancellation of nonlinearities was obtained by dynamical inversion methods. However, uncertain parameters and unmeasured signals are commonly found in practical conditions. To address this issue, an observed-based estimation scheme was proposed to obtain estimates of the unmeasured signals and the trajectory of the modeling error, which are subsequently used to obtain an approximate version of the exact feedback inversion. Numerical simulations for open-loop stable and unstable (e.g., large-amplitude limit cycle) showed that the proposed control scheme provides closed-loop stability despite large model uncertainties.