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Techno-Economic Assessment of the Factory Production of Small Modular Reactor

The demand for electricity continues to grow around the world while pressures remain high to reduce carbon emissions. Nuclear energy provides a strong and reliable baseload power component without a high output of greenhouse gases. Global nuclear energy capacity is increasing with 62 reactors under construction in 14 countries. Nuclear energy will be crucial as energy demands are met with a sustainable and diverse energy portfolio. Small modular reactors (SMRs) are small scale (less than 300 MWe) reactors that incorporate the same advanced technologies included in recent LR nuclear reactor designs. SMRs are designed to include the latest reactor technology including passive safety features. SMRs offer economic advantages over LRs such as lower up-front capital and easier integration into the existing power grid. The modular characteristic of SMRs would allow incremental additions to power plants years after its completion. The cost of constructing SMR power plants will determine their future in the energy industry. Three SMR reactors are in advanced stages of design in the United States; the Westinghouse 225 MWe, mPower 180 MWe and nuScale 45 MWe. SMRs are expected to have lower capital expenses of reactor components due to factory production. Current estimates predict these savings to reduce SMR capital 30-40%. Existing studies have estimated SMR capital using economies of scale and holistic discounts applied to an overall capital expense figure, but do not include the expense of an SMR factory facility. To better understand the actual costs associated with construction of an SMR power plant, capital components will be broken down according to its place in the construction phase. The expense of a factory facility will also be included with SMR capital expenses to determine its significance and benefits to overall capital expenses. Results from this study show that SMRs can compete with LRs in terms of startup costs. The capital cost of building a factory for SMRs was previously overlooked for SMR capital estimates. The annualized capital expenses expected for an SMR factory are very small, but offer significant discounts to the overall capital costs for SMRs. Case 3 shows that factory production can reduce SMR capital expenses to the range of 30%-40% when compared to Case 1 in this study. Factory savings of this magnitude would require factory production of several SMR reactor and generator components including the reactor pressure vessel, control rods, steam generation, and chemical and volume control system, containment, condenser and turbo-generator. SMRs will also benefit from lower indirect expenses due to a much smaller construction duration. It is expected that SMRs will have capital costs competitive with LRs. The differences between Case 2 and Case 3 in this study show that SMRs are heavily dependent on the cost reductions coming from factory production. The factory facility represents a small increase in capital expense, but accounts for a large reduction of cost for factory components. SMRs have the potential to meet growing energy demands in the United States and around the world, but their economic viability is dependent on a factory facility that will lower the capital expenses of reactor and generator components. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Enhancing power plant safety through simulated cyber events - 341

There are gaps in understanding how a cyber-attack would manifest itself within power plants and what these events would look like within the control room from an operator's perspective. This is especially true for nuclear power plants where safety has much broader consequences than nonnuclear plants. The operating and emergency procedures that operators currently use are likely inadequate for targeted cyber-attacks. This research focuses on understanding how a cyber event would affect the operation of the plant, how an operator would perceive the event, and if the operator's actions would keep the plant in a safe condition. This research is part of Sandia's Laboratory Directed Research and Development program where a nuclear power plant cyber model of the control system digital architecture is coupled with a generic pressurized water reactor plant training simulator. Cyber event scenarios will be performed on the coupled system with plant operators. The scenarios simulate plant conditions that may exist during a cyber-attack, component failure, or insider sabotage, and provide an understanding of the displayed information and the actual plant conditions. These scenarios will determine if plant operators can 1) recognize that they are under cyber-attack and 2) take appropriate actions to keep the plant safe. This will also provide the opportunity to assess the operator cognitive workload during such events and identify where improvements might be made. Experiments with nuclear power plant operators will be carried out over FY 2018 and results of the research are expected by the end of FY 2018. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Pressure-Driven Fiber-Optic Sensor for Online Corrosion Monitoring

For many industrial applications, corrosion is a life-limiting phenomenon and therefore requires careful consideration and rigorous experimental testing before structural materials can be reliably deployed, particularly in harsh chemical environments. The traditional approach to measuring corrosion requires exposing many samples to the intended environment and then extracting them individually at discrete intervals for postexposure characterization. This approach does not provide a high degree of temporal resolution, nor does it provide any real-time information regarding dynamic changes in corrosion rates. Additionally, developing an online corrosion monitor capable of surviving harsh chemical environments could provide valuable information regarding the structural health of components and changing process conditions that could accelerate corrosion. To this end, a corrosion sensor was developed based on a pressure-driven Fabry-Pérot cavity (FPC). This sensor uses a pressure control system to internally pressurize the FPC formed between the sensor’s housing and a metal-embedded singlemode optical fiber. Simultaneous measurement of the change in FPC length using low-coherence interferometry and the applied pressure enables the calculation of the relative changes in the sensor’s diaphragm thickness due to corrosion on its outer surface. Measurements were made in situ while actively corroding the sensor and were validated against surveillance specimens that were corroded simultaneously. The uncertainties in the measured corrosion were analyzed using error propagation of the uncertainties in the measured pressures and displacements and were found to be <1% of the initial diaphragm thickness.

42 ENGINEERING↗

Radiation Protection for the First Korea Heavy-ion Medical Accelerator (KHIMA) Facility - Paper 7

The number of particle therapy facilities is increasing worldwide due to the encouraging results obtained at research facilities such as the Lawrence Berkeley National Laboratory (USA), the Helmholtz Center for Heavy Ion Research GSI (Germany), and the Heavy Ion Medical Accelerator (HIMAC) in Chiba (Japan). The first hospital-based heavy-ion therapy facility is under construction in Busan, Korea, at the Korea Institute of Radiological and Medical Sciences [KIRAMS]. The project was originally designed to develop a compact superconducting cyclotron for hadron therapy able to deliver forefront beams of heavier ions, essentially carbon ions of energy, 430 MeV/u. Radiation protection issues play an important role in every stage of the project such as civil construction planning, control system design, and special technological plants. Monte Carlo transport codes are the best tools to solve these issues and the FLUKA2011 and MCNPX2.7.0 codes are used in this work. Beam loss distributions of cyclotron installations in combination with passive or active beam shaping methods have a particularly high implication on the protection layout of the facility. Methods for shielding and activation calculations are described with an emphasis on carbon ion beams. All the tools and databases require verification. Benchmarking is an instrumental process for verification. An overview of benchmarking efforts will also be given and the need for further benchmarks is discussed. (authors)

43 PARTICLE ACCELERATORS↗

The effect of solidity on the performance of H-rotor Darrieus turbine

Utilization of wind energy has been investigated for a long period of time by different researchers in different ways. Out of which, the Horizontal Axis Wind Turbine and the Vertical Axis Wind Turbine have now advanced design, but still there is scope to improve their efficiency. The Vertical Axis Wind Turbine (VAWT) has the advantage over Horizontal Axis Wind Turbine (HAWT) for working on omnidirectional air flow without any extra control system. A modified H-rotor Darrieus type VAWT is analysed in this paper, which is a lift based wind turbine. The effect of solidity (i.e. chord length, no. of blades) on power coefficient (C{sub P}) of H-rotor for different tip speed ratios is numerically investigated. The study is conducted using time dependent RANS equations using SST k-ω model. SIMPLE scheme is used as pressure-velocity coupling and in all cases, the second order upwind discretization scheme is chosen for getting more accurate solution. In results, different parameters are compared, which depict the performance of the modified H-rotor Darrieus type VAWT. Double layered H-rotor having inner layer blades with longer chord gives higher power coefficient than those have inner layer blades with smaller chord.

17 WIND ENERGY↗

Neutrino Interactions

The neutrino group of the University of Tennessee, Knoxville was involved from 05/01/2013 to 04/30/2015 in the neutrino physics research funded by DOE-HEP grant DE-SC0009861. Contributions were made to the Double Chooz nuclear reactor experiment in France where second detector was commissioned during this period and final series of measurements has been started. Although Double Chooz was smaller experimental effort than competitive Daya Bay and RENO experiments, its several advantages make it valuable for understanding of systematic errors in measurements of neutrino oscillations. Double Chooz was the first experiment among competing three that produced initial result for neutrino angle θ 13 measurement, giving other experiments the chance to improve measured value statistically. Graduate student Ben Rybolt defended his PhD thesis on the results of Double Chooz experiment in 2015. UT group has fulfilled all the construction and analysis commitments to Double Chooz experiment, and has withdrawn from the collaboration by the end of the mentioned period to start another experiment. Larger effort of UT neutrino group during this period was devoted to the participation in another DOE-HEP project - NOvA experiment. The 14,000-ton "FAR" neutrino detector was commissioned in northern Minnesota in 2014 together with 300-ton "NEAR" detector located at Fermilab. Following that, the physics measurement program has started when Fermilab accelerator complex produced the high-intensity neutrino beam propagating through Earth to detector in MInnessota. UT group contributed to NOvA detector construction and developments in several aspects. Our Research Associate Athanasios Hatzikoutelis was managing (Level 3 manager) the construction of the Detector Control System. This work was successfully accomplished in time with the commissioning of the detectors. Group was involved in the development of the on-line software and study of the signatures of the cosmic ray backgrounds. Flumerfelt and another graduate student Philip Mason were also studying the non-linearity properties of the NOvA liquid scintillator - information that will be essential at the final stages of NOvA data analysis. Philip Mason also studied the response of the FAR NOvA detector in correlation with solar flares. Flumerfelt and Mason successfully defended their PhD in 2015. Also, undergraduate student Cameron Blake Erickson has defended his undergraduate thesis on the NOvA liquid scintillator studies with Compton gamma spectrometer at UT.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Effect of injected flux and current temporal phasing on self-organization in the HIT-SI3 experiment

The HIT-SI3 device at the University of Washington uses three oscillating inductive helicity injectors to form and sustain spheromak plasma equilibria. By adjusting the temporal phase of the injector waveforms with respect to each other, the toroidal spectrum of the imposed perturbations can be controlled. Using a recently implemented GPU-based control system, the available mode spectra were explored experimentally by scanning the space of relative injector phasing. In this space, significant variation in the toroidal mode spectrum ($n$ = 1, 2, 3) of the perturbations was observed. Additionally, variation in characteristics of driven equilibria was also observed, including a ≈ $30$% range in toroidal current gain ($I$ $Φ$ / $I$ $Inj$ ). Experimental results are compared with both a composite-equilibria and nonlinear dynamic model, including extended MHD simulations using the NIMROD code and composite Taylor state equilibria computed using the PSI-Tet code. In conclusion, qualitative agreement is seen with the nonlinear models, but not with composite-equilibria models, suggesting the use of nonlinear models to better capture observed plasma dynamics and provide predictive use for future experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

MO-G-BRD-01: Point/Counterpoint Debate: Arc Based Techniques Will Make Conventional IMRT Obsolete

A variety of intensity modulated radiation therapy (IMRT) delivery techniques have been developed that have provided clinicians with the ability to deliver highly conformal dose distributions. The delivery techniques include compensators, step-and-shoot IMRT, sliding window IMRT, volumetric modulated arc therapy (VMAT), and tomotherapy. A key development in the field of IMRT was the introduction of new planning algorithms and delivery control systems in 2007 that made it possible to coordinate the gantry rotation speed, dose rate, and multileaf collimator leaf positions during the delivery of arc therapy. With these developments, VMAT became a routine clinical tool. The use of VMAT has continued to grow in recent years and some would argue that this will soon make conventional IMRT obsolete, and this is the premise of this debate. To introduce the debate, David Shepard, Ph.D. will provide an overview of IMRT delivery techniques including historical context and how they are being used today. The debate will follow with Richard Popple, Ph.D. arguing FOR the Proposition and Peter Balter, Ph.D. arguing AGAINST it. Learning Objectives: Understand the different delivery techniques for IMRT. Understand the potential benefits of conventional IMRT. Understand the potential benefits of arc-based IMRT delivery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗

Transmission diamond imaging detector

Many modern synchrotron techniques are trending toward use of high flux beams and/or beams which require enhanced stability and precise understanding of beam position and intensity from the front end of the beamline all the way to the sample. For high flux beams, major challenges include heat load management in optics (including the vacuum windows) and a mechanism of real-time volumetric measurement of beam properties such as flux, position, and morphology. For beam stability in these environments, feedback from such measurements directly to control systems for optical elements or to sample positioning stages would be invaluable. To address these challenges, we are developing diamond-based instrumented vacuum windows with integrated volumetric x-ray intensity, beam profile and beam-position monitoring capabilities. A 50 µm thick single crystal diamond has been lithographically patterned to produce 60 µm pixels, creating a >1kilopixel free-standing transmission imaging detector. This device, coupled with a custom, FPGA-based readout, has been used to image both white and monochromatic x-ray beams and capture the last x-ray photons at the National Synchrotron Light Source (NSLS). This technology will form the basis for the instrumented end-station window of the x-ray footprinting beamline (XFP) at NSLS-II.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Creating Cybersecurity Professionals of the Future

Cybersecurity is a growing public concern with more threats and vulnerabilities being discovered and exploited by adversaries each day. In particular, industrial control systems (ICS) are at a higher risk because their components were not designed with cybersecurity in mind. With increased risk to ICS, it is vital that the employees who work on the system are trained in cybersecurity best practices and the latest threats. Research has shown that there are currently no curriculum standards for an ICS cybersecurity professional, which may contribute to the issues faced during the hiring process. In fact, most individuals require extensive post-hire training before they can begin normal operations. The goal in cybersecurity is to become operationally resilient, which means in part that employees of an organization are trained to prevent and handle a cybersecurity incident. Therefore, the authors present a project that offers a solution to the education gap by creating a workforce pipeline for ICS cybersecurity professionals. The project is a virtual ecosystem for collaboration and transforming operational resilience (VECTOR). VECTOR incorporates many different efforts to increase operational resilience including the development of ICS cybersecurity curriculum and apprenticeships.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

The resilient hybrid fiber sensor network with self-healing function

This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Application of Modular Design in Abatement of Fuel Element Debris (FED) Liquid Waste Stream - 16635

This paper provides a description of the processes applied within the Aqueous Discharge Abatement Plant (ADAP) at Bradwell nuclear power plant in the UK. This incorporates the Fuel Element Debris (FED) abatement plant and the Modular Active Effluent Treatment Plant (MAETP). These plants are housed in adjacent, but separate, structures and are inter-linked and share common services and control systems. The FED abatement plant, which has a shorter mission than MAETP, can be removed for decommissioning or redeployment without any impact to MAETP operation. ADAP treats aqueous waste streams generated during the ongoing decontamination and decommissioning (D and D) operations for release from the Bradwell Power Station. The plant is designed to receive and treat two major classes of liquids: 1. Slightly contaminated water from various D and D sources and collected rainwater from the power station, referred to as Aqueous Effluent (AE). 2. Dissolved fuel element debris solution. This comprises of contaminated magnesium alloy (generated during the stripping of external structures from spent Magnox fuel elements prior to shipment for reprocessing) which has been dissolved in nitric acid. All received wastes are treated to remove heavy metals and radioactive constituents prior to isolation, sampling, verification, and ultimately release to the Blackwater Estuary. The treatment consists of multiple processes including precipitation, filtration, adsorption and ion exchange carefully designed to remove targeted radionuclides and heavy metals. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Potential applications of industrial wireless technologies in the future HTR - 18505

High Temperature Reactor (HTR) is a kind of promising nuclear reactor for supplying electricity and heat with inherent safety. The High Temperature Reactor-Pebble bed Modular reactor (HTR-PM) in China is equipped with the Distributed Control System (DCS) where wired network is applied mainly based on fiber. Considering the difficulty and cost of implementation, the flexibility of network configuration and maintenance, the industrial wireless network might be potential for some cases in the network of the next generation of HTR. Nowadays, there are several technologies available for choice, such as wireless HART, WIA-PA and ZigBee. Characteristics of these technologies are introduced. The most important factors for choice of the technology of network are the required reliability and latency tolerance of communication. Analysis and classification of the communications needed in the network of the HTR are carried out, and a comparison of popular industrial wireless technologies, including the reliability, the latency, the communication distance, and the difficulty and cost of implementation is made. Generally speaking, considering the low latency, high reliability and the compatibility with HART devices, wireless HART is promising. WIA-PA could be applied if redundant gateway is required. ZigBee might show its advantages in power consumption and cost. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

Analysis of DWPF Sludge Batch 7a (Macrobatch 8) Pour Stream Samples

The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 7a (SB7a), also referred to as Macrobatch 8 (MB8), in June 2011. SB7a is a blend of the heel of Tank 40 from Sludge Batch 6 (SB6) and the SB7a material that was transferred to Tank 40 from Tank 51. SB7a was processed using Frit 418. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program (GPCP), which is governed by the DWPF Waste Compliance Plan, and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. Three pour stream glass samples and two Melter Feed Tank (MFT) slurry samples were collected while processing SB7a. These additional samples were taken during SB7a to understand the impact of antifoam and the melter bubblers on glass redox chemistry. The samples were transferred to the Savannah River National Laboratory (SRNL) where they were analyzed. The following conclusions were drawn from the analytical results provided in this report: (1) The sum of oxides for the official SB7a pour stream glass is within the Product Composition Control System (PCCS) limits (95-105 wt%). (2) The average calculated Waste Dilution Factor (WDF) for SB7a is 2.3. In general, the measured radionuclide content of the official SB7a pour stream glass is in good agreement with the calculated values from the Tank 40 dried sludge results from the SB7a Waste Acceptance Program Specification (WAPS) sample. (3) As in previous pour stream samples, ruthenium and rhodium inclusions were detected by Scanning Electron Microscopy-Electron Dispersive Spectroscopy (SEM-EDS) in the official SB7a pour stream sample. (4) The Product Consistency Test (PCT) results indicate that the official SB7a pour stream glass meets the waste acceptance criteria for durability with a normalized boron release of 0.64 g/L, which is an order of magnitude less than the Environmental Assessment (EA) glass. (5) The measured density of the SB7a pour stream glass was 2.7 g/cm 3 . (6) The Fe 2+ ΣFe ratios of the SB7a pour stream samples were in the range of 0.04-0.13, while the MFT sample glasses prepared by SRNL were in the range of 0.02-0.04.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Precursor Analysis Report: Remote Access Attack on Oldsmar Water Treatment Facility 2021

The Remote Access Attack on Oldsmar Water Treatment Facility 2021 Precursor Analysis Report leverages publicly available information about the Oldsmar cyber attack and catalogs anomalous observables for each technique employed in the attack. This analysis is based upon the methodology of the Cybersecurity for the Operational Technology Environment (CyOTE) program. On 5 February 2021, an adversary gained unauthorized remote access to Bruce T. Haddock Water Treatment Plant in Oldsmar, Florida, which provides treated water to 15,000 customers. The adversary accessed the facility’s Supervisory Control and Data Acquisition (SCADA) workstation and human machine interface (HMI) to change the chemical concentration of sodium hydroxide, commonly referred to as lye and used to regulate acidity levels, from 100 parts per million (PPM) to 11,100 PPM. The chemical was raised to lethal levels that if ingested could lead to serious soft tissue damage, burns, or even death. The facility, however, had redundancies and alarms in place to alert personnel of dangerous chemical levels, and facility officials stated it would have taken 24 to 36 hours for the chemical changes to affect the water supply. Researchers and analysts identified six unique techniques utilized during the attack with a total of 23 observables using MITRE ATT&CK® for Industrial Control Systems. The CyOTE program assesses observables accompanying techniques used prior to the triggering event to identify opportunities to detect malicious activity. If observables accompanying the attack techniques are perceived and investigated prior to the triggering event, earlier comprehension of malicious activity can take place. Four of the identified techniques used during the Oldsmar cyber attack were precursors to the triggering event. Analysis identified 21 observables associated with these precursor techniques, 20 of which were assessed to have an increased likelihood of being perceived in the minutes preceding the triggering event. The response and comprehension time could have been reduced if the observables had been identified earlier. The information gathered in this report contributes to a library of observables tied to a repository of artifacts, data sources, and technique detection references for practitioners and developers to support the comprehension of indicators of attack. Asset owners and operators can use these products if they experience similar observables or to prepare for comparable scenarios.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Longitudinal data analysis in support of functional stability concepts for leachate management at closed municipal landfills

Highlights: • Longitudinal data analysis using a mixed-effects regression model. • Dataset consisted of a total of 1402 samples from 101 closed municipal landfills. • Target analytes and classes generally showed predictable degradation trends. • Validates historical studies focused on macro organic indicators such as BOD. • BOD can serve as “gateway” indicator for planning leachate management. - Abstract: Landfill functional stability provides a target that supports no environmental threat at the relevant point of exposure in the absence of active control systems. With respect to leachate management, this study investigates “gateway” indicators for functional stability in terms of the predictability of leachate characteristics, and thus potential threat to water quality posed by leachate emissions. Historical studies conducted on changes in municipal solid waste (MSW) leachate concentrations over time (longitudinal analysis) have concentrated on indicator compounds, primarily chemical oxygen demand (COD) and biochemical oxygen demand (BOD). However, validation of these studies using an expanded database and larger constituent sets has not been performed. This study evaluated leachate data using a mixed-effects regression model to determine the extent to which leachate constituent degradation can be predicted based on waste age or operational practices. The final dataset analyzed consisted of a total of 1402 samples from 101 MSW landfills. Results from the study indicated that all leachate constituents exhibit a decreasing trend with time in the post-closure period, with 16 of the 25 target analytes and aggregate classes exhibiting a statistically significant trend consistent with well-studied indicators such as BOD. Decreasing trends in BOD concentration after landfill closure can thus be considered representative of trends for many leachate constituents of concern.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Leak Detection and H2 Sensor Development for Hydrogen Applications

The objectives of this report are: (1) Develop a low cost, low power, durable, and reliable hydrogen safety sensor for a wide range of vehicle and infrastructure applications; (2) Continually advance test prototypes guided by materials selection, sensor design, electrochemical R&D investigation, fabrication, and rigorous life testing; (3) Disseminate packaged sensor prototypes and control systems to DOE Laboratories and commercial parties interested in testing and fielding advanced prototypes for cross-validation; (4) Evaluate manufacturing approaches for commercialization; and (5) Engage an industrial partner and execute technology transfer. Recent developments in the search for sustainable and renewable energy coupled with the advancements in fuel cell powered vehicles (FCVs) have augmented the demand for hydrogen safety sensors. There are several sensor technologies that have been developed to detect hydrogen, including deployed systems to detect leaks in manned space systems and hydrogen safety sensors for laboratory and industrial usage. Among the several sensing methods electrochemical devices that utilize high temperature-based ceramic electrolytes are largely unaffected by changes in humidity and are more resilient to electrode or electrolyte poisoning. The desired sensing technique should meet a detection threshold of 1% (10,000 ppm) H 2 and response time of {approx_equal}1 min, which is a target for infrastructure and vehicular uses. Further, a review of electrochemical hydrogen sensors by Korotcenkov et.al and the report by Glass et.al suggest the need for inexpensive, low power, and compact sensors with long-term stability, minimal cross-sensitivity, and fast response. This view has been largely validated and supported by the fuel cell and hydrogen infrastructure industries by the NREL/DOE Hydrogen Sensor Workshop held on June 8, 2011. Many of the issues preventing widespread adoption of best-available hydrogen sensing technologies available today outside of cost, derive from excessive false positives and false negatives arising from signal drift and unstable sensor baseline; both of these problems necessitate the need for unacceptable frequent calibration.

08 HYDROGEN↗

Implementation and Operation of Power Flow Control Solutions for Transmission Systems

Power-flow controls (PFCs) technologies provide a suite of alternatives to more-efficiently direct the flow of power on the grid, improving flexibility and enabling the grid to be more responsive and resilient. PFCs can be used in many cases to mitigate overloads and consequently defer the installation of grid-expansion projects. They can also be suitable options in situations where new transmission lines cannot be built because of environmental constraints, land use, or other types of restrictions. Other uses include mitigation of loop or unintended flows, forcing of contractual or scheduled flows, reduction of congestion, and mitigation solutions during large maintenance or construction projects. While many studies have demonstrated the potential economic benefits of PFC for different types of applications, the implementation implications of using multiple PFCs for system operation and reliability have not been analyzed in detail. The lack of information and practical experience on these aspects hinders adoption of this technology. One use case would be that multiple PFCs are required to coordinate congestion management. In such cases, multiple PFCs are deployed in a meshed power system to control power flows across a wide area. The challenges are associated with PFC interaction—namely, the self and mutual power-flow sensitivity of each PFC, which must be accounted for in the calculation of the respective operating setpoints. This report analyzes implementation and operation that must be considered in evaluating transmission solutions using PFCs. The report first analyzes attributes with which PFC-based solutions should comply, based on the objective and characteristics of each particular use case. It then describes different approaches for coordinated control of multiple PFC devices for different applications, including options to avoid adverse interactions and reduce risks due to inappropriate coordination. Control and operation are illustrated through case studies performed on both generic and actual power system models. This report provides insights for transmission planners and operation engineers about the implementation of PFC-based transmission solutions; consequently, it will help them make informed decisions about the adoption of the technology.

24 POWER TRANSMISSION AND DISTRIBUTION↗

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