Modelica models for a Heat Recovery Steam Generator (HRSG) and Multiple Effect Evaporator have been developed. These models have been validated against results from literature and from an actual cogeneration system on the campus of NC State University. The models are capable of connecting to other components to create multi-input, multi-output energy systems with storage, also known as integrated energy systems. An existing 35 MW gas turbine model is connected to the HRSG model created for this project to produce 9 bar steam. The high pressure steam feeds a backpressure steam turbine from the library to generate additional electric power. 2 bar steam leaves the turbine to supply an 8 effect MEE to generate water for a community. As part of the effort, three research papers were submitted (two published in ANS Proceedings and one submitted to Applied Energy).

Small modular reactors (SMRs) are reactor designs producing less than 300 MWe and are generally planned for deployment as multimodule nuclear power plants. The possibility of factory-manufactured, flexibly sized plants expands the opportunities for nuclear power to different communities and industries, including manufacturing plants that currently utilize fossil fuels to produce both steam and electricity. This paper examines the feasibility of coupling a NuScale SMR with a midsize pulp and paper mill in the Southeastern United States. A steady-state mill model was developed in Aspen HYSYS, based on real data from the operation of the mill, and modified it to include the SMR while maintaining steam quality requirements and making as few changes as possible to existing equipment. Dynamic plant models were also developed Dymola to demonstrate possible plant conditions, using three configurations. Preliminary results suggest that, while SMR coupling is physically feasible, its economic feasibility is limited by the differences in steam and electricity demands. Because of limitations in the amount of steam the mill can take from the SMR, sizing the SMR for the plant's steam demand may result in an electricity deficit, or vice versa. Dynamic analyses show that the addition of a thermal storage system could reduce such deficits, but this entails its own challenges. Each plant must determine the best configuration and control scheme for itself, based on its electricity and heat needs, including the peak duration and intensity for both. Ultimately, an implementation of SMRs with manufacturing processes would benefit from partnering with a local utility to purchase excess electricity generated by the SMR. This will help manufacturing facilities meet their environmental and cost-savings goals, in addition to meeting the need for cost-effective baseload power across the United States.

Small modular reactors (SMRs) are small-scale reactor designs (< 300 MWe), generally planned for deployment as multi-module nuclear power plants. Due to their small size, SMR modules could be manufactured in a factory and deployed to a site via truck or rail for installation and fueling. SMRs are being evaluated for their ability to provide both power and steam, such that they could be a viable replacement for fossil fuels. SMRs have been considered for coupling to manufacturing processes in addition to being connected to the grid, allowing them to follow the net grid demand in a "load following" operational mode during times of high renewable generation. Alternately, SMRs could be used to replace cogeneration and combined-cycle processes at manufacturing plants which utilize natural gas and other fossil fuels. Idaho National Laboratory (INL) is studying the use of SMRs for large-scale manufacturing processes that require both electricity and steam. The current study examines the integration of a SMR with two mid-size pulp and paper mills in the southeastern United States. The study consists of three parts: steady-state analysis of the mill, elimination of fossil fuel use in the lime kilns, and economic analysis of the modified plant operations. A steady-state model of each mill is developed in Aspen HYSIS based on real data from the operation of each mill. The steady-state model is then modified to include the SMR while maintaining production steam quality and making as few changes to existing equipment as possible. This model gives an estimate of the minimum requirements for SMR output, as well as the change in generation by existing boilers and turbines. With an overall picture of the new plant operation and determining the number of SMR modules required, further changes are suggested to minimize or completely eliminate fossil fuel use from the plant. Apart from steam generation, the largest consumer of fossil fuels at the plant is typically the lime kilns. Conversion of the lime kilns from fossil fuel combustion to electric heating is the most feasible solution to eliminate fossil fuels. This study finds that electric lime kilns are economical when the plant has a surplus This study presents a feasible example of using an SMR as a substitute for fossil fuel cogeneration. If this approach were expanded across the manufacturing industry, it would have a significant impact on environmental emissions and air quality.

Desalination is becoming a popular and necessary process for producing fresh water in deserts and areas across the word affected by drought. Small Modular Reactor (SMR) technology is attractive for this application because it cogenerates steam and electricity to run multiple desalination processes at once. Multi-Effect Distillation (MED) technology requires steam to evaporate fresh water, while Reverse Osmosis (RO) only requires electricity for desalination. While RO typically produces fresh water more efficiently than MED, condensate from the evaporators can be flashed and sent to an absorption chiller to produce chilled water for space cooling. This study uses a 6-effect backward feed evaporator model to analyze revenues and savings from total freshwater and chilled water produced and determine the steam pressure from the SMR and loading schedule to produce maximum revenue for the specified desalination facility. Three loading schedules were chosen for this study: base loading, day/night loading, and diurnal demand loading, and revenues were calculated by closely matching a demand of 50,000 people. Day/night loading resulted in significantly more revenue and chilled water production than the other two schedules. The coupling of RO and MED systems to a small modular reactor could result in increased revenue for a desalination plant while meeting the freshwater demands of a community.

The increased penetration of intermittent renewable energy technologies such as wind and solar power can strain electric grids, forcing carbon-based and nuclear sources of energy to operate in a load-follow mode. For nuclear reactors, load-follow operation can be undesirable due to the associated thermal and mechanical stresses placed on the fuel and other reactor components. Various methods of thermal energy storage (TES) can be coupled to nuclear (or renewable) power sources to help absorb grid variability caused by daily load demand changes and renewable intermittency. Two TES techniques are investigated as candidate thermal reservoirs to be used in conjunction with a small modular reactor (SMR): a two-tank sensible heat storage system and a stratified chilled-water storage system. The goal when coupling the two systems to the SMR is to match turbine output and demand and bypass steam to the TES systems to maintain reactor power at approximately 100%. Simulations of integral pressurized water reactor dynamics are run in a high-fidelity FORTRAN model developed at North Carolina State University. Both TES systems are developed as callable FORTRAN subroutines to model the time-varying behavior associated with different configurations of these systems when connected to the SMR simulator. Simulation results reveal the sensible heat storage system is capable of meeting turbine demand and maintaining reactor power constant while providing enough steam to power four absorption chillers for chilled-water production and storage. The stored chilled water is used to supplement cooling loads of an adjacent facility.

Air-conditioning loads during the warmer months of the year are large contributors to an increase in the daily peak electrical demand. Traditionally, utility companies boost output to meet daily cooling load spikes, often using expensive and polluting fossil fuel plants to match the demand. Likewise, heating, ventilation, and air conditioning (HVAC) system components must be sized to meet these peak cooling loads. However, the use of a properly sized stratified chilled-water storage system in conjunction with conventional HVAC system components can shift daily energy peaks from cooling loads to off-peak hours. This process is examined in light of the recent development of small modular nuclear reactors (SMRs). In this study, primary components of an air-conditioning system with a stratified chilled-water storage tank were modeled in FORTRAN 95. A basic chiller operation criterion was employed. Simulation results confirmed earlier work that the air-conditioning system with thermal energy storage (TES) capabilities not only reduced daily peaks in energy demand due to facility cooling loads but also shifted the energy demand from on-peak to off-peak hours, thereby creating a more flattened total electricity demand profile. Thus, coupling chilled-water storage-supplemented HVAC systems to SMRs is appealing because of the decrease in necessary reactor power cycling, and subsequently reduced associated thermal stresses in reactor system materials, to meet daily fluctuations in cooling demand. Also, such a system can be used as a thermal sink during reactor transients or a buffer due to renewable intermittency in a nuclear hybrid energy system (NHES).

Single effect, lithium bromide absorption chillers offer the ability to utilize low-pressure steam to produce chilled water for satisfying various comfort cooling needs. Previous attempts have been made to characterize dynamic and steady-state absorption chiller operation. Though these models perform adequately, they are based on hot water driven absorption chillers. Commercially available absorption chillers often can run on both hot water and low-pressure steam. In this paper, the mathematical framework for a dynamic single effect, lithium bromide absorption chiller model capable of using low-pressure steam is presented. The transient thermodynamic FORTRAN model is grounded on mass, energy, and species balances, and builds on prior modeling efforts. Well-known correlations for heat transfer coefficients are used to describe both tube-side and shell-side heat transfer rates in each primary chiller component. To account for the absorption chiller unit receiving steam, a heat transfer model for condensation inside horizontal tubes based on distinct internal condensation flow regimes is incorporated within the generator. This heat transfer model is used with two-phase flow pressure drop equations to establish steam temperature, quality, and pressure along the generator tube bundle. Steam consumption trends are established as a function of fluctuating external conditions. These trends reasonably align with information made available online by the manufacturer, though some deviation does occur at low chiller capacities and cooling water temperatures. Additionally, the transient response of internal and external parameters from a step increase in heat input supplied to the generator mimics results of other dynamic absorption chiller models found throughout literature.

Presented are the results of experiments designed to investigate flame lift-off behavior in the hysteresis regime for low Reynolds number turbulent flows. The hysteresis regime refers to the situation where the jet flame has dual positions favorable to flame stabilization: attached and lifted. Typically, a jet flame is lifted off of a burner and stabilized at some downstream location at a pair of fuel and coflow velocities that is unique to a flame at that position. Since the direction from which that condition is arrived at is important, there is an inherent hysteretic behavior. To supplement previous research on hysteretic behavior in the presence of no coflow and low coflow velocities, the current research focuses on flames that are lifted and reattached at higher coflow velocities, where the flame behavior includes an unexpected downstream recession at low fuel velocities. Observations on the flame behavior related to nozzle exit velocity and coflow velocity are made using video imaging of flame sequences. The results show that a flame can stabilize at a location downstream despite a decrease in the local excess jet velocity and assist in determining the effect of coflow velocity magnitude on hysteretic behavior. These observations are of utility in designing maximum turndown burners in air coflow, especially for determining stability criteria in low fuel-flow applications.

A study of the characteristics of turbulent lifted-jet flames in the hysteresis regime was performed using methane and ethylene fuels in laminar and turbulent air coflows. Reattachment velocities and lifted flame heights just prior to reattachment vary linearly as for laminar flames in coflow. The flow regime of the coflow (i.e., laminar or turbulent) did not appear to affect the behavior of these flames. These observations are of utility in designing maximum turndown burners in air coflow, especially for determining stability criteria in low fuel-flow applications.

This study presents the results of experiments designed to investigate flame lift-off behavior to nozzle velocity, co-flow velocity, fuel-type, and nozzle size for low Reynolds Number turbulent flows ( in and near the hysteresis regime). Local excess jet velocities are computed using jet relations from Tieszen et al. The results show that the local excess jet velocity remains linear with respect to nozzle velocity through most of the hysteresis regime, even though flame lift-off height is not linear. This suggests a non-linear relation not captured by Kalghatgi ( 1984) for lift-off in the near field and hysteresis regime. Local excess jet velocities at the reattachment point were also computed for flames that are lifted more than three nozzle diameters above the burner. The results show that there is a minimum excess jet velocity for which a flame can stabilize. This minimum velocity is inversely proportional to the laminar burning velocity of the fuel squared. A new relation for lift-off height at the reattachment point for flames in the hysteresis region is derived and compared to experimental data.

The current profile and core magnetic field fluctuation amplitudes in a reversed-field pinch are measured by using a high-resolution polarimetry–interferometry system. This paper presents data showing a redistribution of the current during a sawtooth crash. Also, the core magnetic field fluctuation amplitude is observed to increase at a sawtooth crash consistent with the idea of nonlinearly driven dynamo current. In addition, the parallel current density increases in the outer region of the plasma during auxiliary pulsed parallel current drive. This was expected, as the external application of an edge parallel electric field is designed to flatten the current profile providing an equilibrium closer to the minimum energy Taylor state. However, the current density also increases in the core, relative to standard plasmas. This increase can be explained by a reduction of the dynamo (anti)current drive in the core that should accompany the measured reduction of magnetic fluctuations and by a drop in resistivity caused by the increased confinement of fast electrons.

Confinement of runaway electrons has been observed for the first time in a reversed field pinch during improved-confinement plasmas in the Madison Symmetric Torus. Energy-resolved hard-x-ray flux measurements have been used to determine the velocity dependence of the electron diffusion coefficient, utilizing computational solutions of the Fokker-Planck transport equation. With improved-confinement, the fast electron diffusivity drops by 2 orders of magnitude and is independent of velocity. This suggests a change in the transport mechanism away from stochastic magnetic field diffusion.

A miniature multichord soft-x-ray detection system has been installed on the Madison Symmetric Torus (MST) reversed-field pinch to study the plasma equilibrium and fluctuation properties of standard- and improved-confinement discharges. Because of the relatively flat MST density and temperature profiles, the spatial resolution is relatively poor along the line of sight. However, the system can resolve line-integrated-emissivity fluctuations which are strongly correlated with the rotating m=1 global magnetic fluctuations as well as heat pulse propagation with edge-resonant m=0 bursts during improved-confinement discharges. Abel inversion based on Park’s inversion techniques indicates peaking of the equilibrium emissivity profile following sawtooth events during standard discharges and profile flattening after m=0 bursts during improved-confinement discharges.

We report on the plasma velocity profile measurements during the pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus (MST) reversed‐field pinch (RFP). In order to decrease fluctuations due to dynamo activities, PPCD was applied to replace the dynamo electric field. As a result, the magnetic fluctuations have been further suppressed, and considerable increase of energy confinement has been already achieved. In the initial stage of PPCD, accompanying sudden reduction of both magnetic fluctuations and radiation from neutral deuterium atoms, the electron temperature increased rapidly. This improvement may be concerned with a current profile change to more stable region. For this change, we have studied whether plasma velocity profile changes To obtain the plasma toroidal velocity profile, we have measured the Doppler shift of several impurity lines. To make sure of the radial maximum emission location, line intensities for each impurity species have been measured at 10 poloidal chords. The dat...

We report on passive measurements of impurity ion velocities during the pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus reversed-field pinch. During PPCD, the electron temperature increased and a sudden reduction of magnetic fluctuations was observed. For this change, we have studied whether plasma velocity is affected. Plasma rotation is observed to decrease during PPCD. From measurements of line intensities for several impurities at 10 poloidal chords, it is found that the impurity line emission shifts outward. The ion temperature of impurities is reasonably connected to that measured by charge exchange recombination spectroscopy from core to edge.

New profile measurements have allowed the electron thermal diffusivity profile to be estimated from power balance in the Madison Symmetric Torus where magnetic islands overlap and field lines are stochastic. The measurements show that (1) the electron energy transport is conductive not convective, (2) the measured thermal diffusivities are in good agreement with numerical simulations of stochastic transport, and (3) transport is greatly reduced near the reversal surface where magnetic diffusion is small.

New developments in Faraday rotation polarimetry have provided the first measurements of current density profile and core magnetic fluctuations in the core of a high-temperature reversed field pinch. This has been achieved by a fast-polarimeter system with time response up to 1 μs and phase resolution <1 mrad. Recent experiments on Madison Symmetric Torus have directly measured radial magnetic field fluctuations in the plasma interior with amplitude 33 G, ∼1%. A broad spectrum of magnetic fluctuations is observed up to 100 kHz. Relaxation of the current density profile at the sawtooth crash occurs on the timescale of 100 μs. Reversed-field pinch behavior is determined in large part by magnetic fluctuations driven by the radial gradient in the parallel current density. Hence, measurement of magnetic fluctuations and the current density profile is essential to understand the link between the current density profile, fluctuations, and transport.

A compact pellet injection system that was recently developed at the Oak Ridge National Laboratory has been installed on the Madison Symmetric Torus (MST) at the University of Wisconsin and used in initial plasma fueling experiments. The system, referred to as a "pellet injector in a suitcase, "is a pipe gun device with a four-barrel capability (presently equipped with two 1.0-mm-bore barrels), and it uses a cryogenic refrigeratorfor in-situ hydrogen pellet formation (typically, D-2 pellets). This new, portable, stand-alone pellet injection system was developed to provide a flexible means of plasma fueling on a wide variety of magnetic confinement devices, with relatively low costs for installation and operation. The injector has already been used to produce useful results with pellets on MST plasmas, including significant and rapid increases (almost 100%) in the line average density, and effectively depositing fuel in the plasma core (central densities of approximate to1.4 x 10(19) m(-3)). In this paper, the injection system, its performance, and reliability will be described, and results from some initial MST pellet experiments will be highlighted.

Magnetic field fluctuations (and the associated current perturbation) have been measured in the core of a high-temperature reversed-field pinch using a newly developed fast-polarimetry system. Radial magnetic field fluctuation levels of approximately 1% are measured in standard-reversed-field pinch discharges which increase to approximately 4% during the sawtooth crash (enhanced dynamo). The fluctuation level is reduced fourfold for high-confinement plasmas where the core-resonant tearing modes are suppressed.