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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

MiR-214 inhibits cell growth in hepatocellular carcinoma through suppression of {beta}-catenin

Highlights: Black-Right-Pointing-Pointer miR-214 is frequently downregulated in human HCC cell lines and tissues. Black-Right-Pointing-Pointer miR-214 overexpression inhibits HCC cell growth in vitro and in vivo. Black-Right-Pointing-Pointer miR-214 directly targets {beta}-catenin 3 Prime -UTR in HCC cells. Black-Right-Pointing-Pointer miR-214 regulates {beta}-catenin downstream signaling molecules. -- Abstract: Mounting evidence has shown that microRNAs (miRNAs) are implicated in carcinogenesis and can function as oncogenes or tumor suppressor genes in human cancers. Recent profile studies of miRNA expression have documented a deregulation of miRNA (miR-214) in hepatocellular carcinoma (HCC). However, its potential functions and underlying mechanisms in hepatocarcinogenesis remain largely unknown. Here, we confirmed that miR-214 is significantly downregulated in HCC cells and specimens. Ectopic overexpression of miR-214 inhibited proliferation of HCC cells in vitro and tumorigenicity in vivo. Further studies revealed that miR-214 could directly target the 3 Prime -untranslated region (3 Prime -UTR) of {beta}-catenin mRNA and suppress its protein expression. Similar to the restoring miR-214 expression, {beta}-catenin downregulation inhibited cell growth, whereas restoring the {beta}-catenin expression abolished the function of miR-214. Moreover, miR-214-mediated reduction of {beta}-catenin resulted in suppression of several downstream genes including c-Myc, cyclinD1, TCF-1, and LEF-1. These findings indicate that miR-214 serves as tumor suppressor and plays substantial roles in inhibiting the tumorigenesis of HCC through suppression of {beta}-catenin. Given these, miR-214 may serve as a useful prognostic or therapeutic target for treatment of HCC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

MTA3 regulates CGB5 and Snail genes in trophoblast

Highlights: •Impaired MTA3, raised CGB5 and Snail expression are associated with preeclampsia. •Knock-down of MTA3 causes up-regulation of CGB5 and Snail genes in BeWo cells. •MTA3 occupies CGB5 and Snail gene promoters in BeWo cells. -- Abstract: Secreted by the placental trophoblast, human chorionic gonadotropin (hCG) is an important hormone during pregnancy and is required for the maintenance of pregnancy. Previous studies have shown that dys-regulation of hCG expression is associated with preeclampsia. However, the exact relationship between altered hCG levels and development of preeclampsia is unknown. Metastasis associated protein 3 (MTA3), a chromatin remodeling protein, is abundantly expressed in the placental trophoblasts, but its function is unknown. In breast cancer, MTA3 has been shown to repress the expression of Snail and cell migration. However, whether MTA3 acts similarly in the trophoblast has not been investigated. In the present study, we examined the role of MTA3 in regulating the hCG β-subunit gene (gene name: CGB5) and Snail expression in the trophoblast cell line, BeWo, as well as its relevance to the high hCG expression levels seen in preeclampsia. First, we investigated MTA3 expression in preeclamptic placenta as compared to normal control placenta via gene expression microarray and qRT-PCR and found that MTA3 was significantly down-regulated, whereas both CGB5 and Snail were up-regulated in preeclamptic placenta. Secondly, we knocked down MTA3 gene in trophoblast cell line BeWo and found Snail and hCG were both up-regulated, suggesting that MTA3 represses Snail and hCG gene expression in trophoblasts. Next, we cloned the CGB5 and Snail promoters into the pGL3-basic vector individually and found that silencing of MTA3 by siRNA resulted in an increase of both CGB5 and Snail promoter activities. To confirm that this MTA3 inhibition is a direct effect, we performed a chromatin immune-precipitation (ChIP) assay and found that MTA3 occupied the proximal promoter regions of both Snail and hCG within BeWo cells. Furthermore, we examined MTA3 expression in placental trophoblast by immunohistochemistry and found that MTA3 expression was higher in villous cytotrophoblasts versus syncytiotrophoblasts, which supports an inverse association of MTA3 with hCG expression. Lastly, using the well-characterized trophoblast fusion model, we examined MTA3 and hCG levels in forskolin-treated BeWo cells and found that MTA3 down-regulation was accompanied by an up-regulation of hCG. These data further suggest that MTA3 is repressing placental hCG expression. In summary, MTA3 plays a critical role in repressing hCG and Snail in placenta trophoblast and its deregulation is associated with preeclampsia.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Up-regulation of CHAF1A, a poor prognostic factor, facilitates cell proliferation of colon cancer

Highlights: • We identified that CHAF1A was up-regulated in colon tumor mucosa in TMA. • The expression pattern of CHAF1A was validated with qPCR and western-blot. • CHAF1A overexpression is an independent indicator for poor colon cancer survival. • CHAF1A facilitates cell proliferation of colon cancer both in vitro and in vivo. - Abstract: Deregulation of chromatin assembly factor 1, p150 subunit A (CHAF1A) has recently been reported to be involved in the development of some cancer types. In this study, we identified that the frequency of positive CHAF1A staining in primary tumor mucosa (45.8%, 93 of 203 samples) was significantly elevated compared to that in paired normal mucosa (18.7%, 38 of 203 samples). The increased expression was strongly associated with cancer stage, tumor invasion, and histological grade. The five-year survival rate of patients with CHAF1A-positive tumors was remarkably lower than that of patients with CHAF1A-negative tumors. Colon cancer cells with CHAF1A knockdown exhibited decreased cell growth index, reduction in colony formation ability, elevated cell apoptosis rate as well as impaired colon tumorigenicity in nude mice. Hence, CHAF1A upregulation functions as a poor prognostic indicator of colon cancer, potentially contributing to its progression by mediating cancer cell proliferation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Constitutive NF-κB activation and tumor-growth promotion by Romo1-mediated reactive oxygen species production

Highlights: • Romo1 expression is required for constitutive nuclear DNA-binding activity of NF-κB. • Romo1 depletion suppresses tumor growth in vivo. • Romo1 presents a potential therapeutic target for diseases. - Abstract: Deregulation of nuclear factor-κB (NF-κB) and related pathways contribute to tumor cell proliferation and invasion. Mechanisms for constitutive NF-κB activation are not fully explained; however, the underlying defects appear to generate and maintain pro-oxidative conditions. In hepatocellular carcinoma (HCC) tissues, up-regulation of reactive oxygen species modulator 1 (Romo1) correlates positively with tumor size. In the present study, we showed that Romo1 expression is required to maintain constitutive nuclear DNA-binding activity of NF-κB and transcriptional activity through constitutive IκBα phosphorylation. Overexpression of Romo1 promoted p65 nuclear translocation and DNA-binding activity. We also show that Romo1 depletion suppressed anchorage-independent colony formation by HCC cells and suppressed tumor growth in vivo. Based on these findings, Romo1 may be a principal regulatory factor in the maintenance of constitutive NF-κB activation in tumor cells. In the interest of anti-proliferative treatments for cancer, Romo1 may also present a productive target for drug development.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

MiRNA-125a-5p inhibits glioblastoma cell proliferation and promotes cell differentiation by targeting TAZ

Highlights: • Expression of miR-125a-5p is inversely correlated with that of TAZ in glioma cells. • MiR-125a-5p represses TAZ expression in glioma cells. • MiR-125a-5p directly targets the 3′ UTR of TAZ mRNA and promotes its degradation. • MiR-125a-5p represses CTGF and survivin via TAZ, and inhibits glioma cell growth. • MiR-125a-5p inhibits the stem cell features of HFU-251 MG cells. - Abstract: Glioblastoma (GBM) is the most lethal brain tumor due to the resistance to conventional therapies, such as radiotherapy and chemotherapy. TAZ, an important mediator of the Hippo pathway, was found to be up-regulated in diverse cancers, including in GBM, and plays important roles in tumor initiation and progression. However, little is known about the regulation of TAZ expression in tumors. In this study, we found that miR-125a-5p is an important regulator of TAZ in glioma cells by directly targeting the TAZ 3′ UTR. MiR-125a-5p levels are inversely correlated with that of TAZ in normal astrocytes and a panel of glioma cell lines. MiR-125a-5p represses the expression of TAZ target genes, including CTGF and survivin, and inhibits cell proliferation and induces the differentiation of GBM cells; whereas over-expression of TAZ rescues the effects of miR-125a-5p. This study revealed a mechanism for TAZ deregulation in glioma cells, and also demonstrated a tumor suppressor role of miR-125a-5p in glioblastoma cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Mefloquine effectively targets gastric cancer cells through phosphatase-dependent inhibition of PI3K/Akt/mTOR signaling pathway

Deregulation of PI3K/Akt/mTOR pathway has been recently identified to play a crucial role in the progress of human gastric cancer. In this study, we show that mefloquine, a FDA-approved anti-malarial drug, effectively targets human gastric cancer cells. Mefloquine potently inhibits proliferation and induces apoptosis of a panel of human gastric cancer cell lines, with EC{sub 50} ∼0.5–0.7 μM. In two independent gastric cancer xenograft mouse models, mefloquine significantly inhibits growth of both tumors. The combination of mefloquine with paclitaxel enhances the activity of either drug alone in in vitro and in vivo. In addition, mefloquine potently decreased phosphorylation of PI3K, Akt, mTOR and rS6. Overexpression of constitutively active Akt significantly restored mefloquine-mediated inhibition of mTOR phosphorylation and growth, and induction of apoptosis, suggesting that mefloquine acts on gastric cancer cells via suppressing PI3K/Akt/mTOR pathway. We further show that mefloquine-mediated inhibition of Akt/mTOR singaling is phosphatase-dependent as pretreatment with calyculin A does-dependently reversed mefloquine-mediated inhibition of Akt/mTOR phosphorylation. Since mefloquine is already available for clinic use, these results suggest that it is a useful addition to the treatment armamentarium for gastric cancer. - Highlights: • Mefloquine targets a panel of gastric cancer cell lines in vitro and in vivo. • Combination of mefloquine and paclitaxel is synergistic. • Mefloquine acts on gastric cancer via inhibition of PI3K/Akt/mTOR pathway. • Mefloquine can be repurposed for gastric cancer treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Ikaros limits follicular B cell activation by regulating B cell receptor signaling pathways

The Ikaros transcription factor is essential for early B cell development, but its effect on mature B cells is debated. We show that Ikaros is required to limit the response of naive splenic B cells to B cell receptor signals. Ikaros deficient follicular B cells grow larger and enter cell cycle faster after anti-IgM stimulation. Unstimulated mutant B cells show deregulation of positive and negative regulators of signal transduction at the mRNA level, and constitutive phosphorylation of ERK, p38, SYK, BTK, AKT and LYN. Stimulation results in enhanced and prolonged ERK and p38 phosphorylation, followed by hyper-proliferation. Pharmacological inhibition of ERK and p38 abrogates the increased proliferative response of Ikaros deficient cells. These results suggest that Ikaros functions as a negative regulator of follicular B cell activation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

The journey of integrins and partners in a complex interactions landscape studied by super-resolution microscopy and single protein tracking

Cells adjust their adhesive and cytoskeletal organizations according to changes in the biochemical and physical nature of their surroundings. In return, by adhering and generating forces on the extracellular matrix (ECM) cells organize their microenvironment. Integrin-dependent focal adhesions (FAs) are the converging zones integrating biochemical and biomechanical signals arising from the ECM and the actin cytoskeleton. Thus, integrin-mediated adhesion and mechanotransduction, the conversion of mechanical forces into biochemical signals, are involved in critical cellular functions such as migration, proliferation and differentiation, and their deregulation contributes to pathologies including cancer. A challenging problem is to decipher how stochastic protein movements and interactions lead to formation of dynamic architecture such as integrin-dependent adhesive structures. In this review, we will describe recent advances made possible by super-resolution microscopies and single molecule tracking approaches that provided new understanding on the organization and the dynamics of integrins and intracellular regulators at the nanoscale in living cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Trends in U.S. Venture Capital Investments Related to Energy: 1980 through the Second Quarter of 2010

This report documents trends in U.S. venture capital investments over the period 1980 through the second quarter of calendar year 2010 (2010Q1+Q2). Particular attention is given to U.S. venture capital investments in the energy/industrial sector over the period 1980-2010Q1+Q2 as well as in the more recently created cross-cutting category of CleanTech over the period 1995-2010Q1+Q2. During the early 1980s, U.S. venture capital investments in the energy/industrial sector accounted for more than 20% of all venture capital investments. However subsequent periods of low energy prices, the deregulation of large aspects of the energy industry, and the emergence of fast growing new industries like computers (both hardware and software), biotechnology and the Internet quickly reduced the priority accorded to energy/industrial investments. To wit, venture capital investments related to the energy/industrial sector accounted for only 1% of the $119 billion dollars invested in 2000 by the U.S. venture capital community. The significant increase in the real price of oil that began in 2003-2004 correlates with renewed interest and increased investment by the venture capital community in energy/industrial investment opportunities. Venture capital investments for 2009 for the energy/industrial sector accounted for $2.1 billion or slightly more than 13% of all venture capital invested that year. The total venture capital invested in energy/industrial during the first two quarters of 2010 is close to $1.8 billion accounting for 17% of all venture capital investments during the first two quarters of 2010. In 2009, the aggregate amount invested in CleanTech was $1.8 billion (30% of the total US venture capital invested in that lean year) and for the first two quarters of 2010 US venture capital investments in CleanTech have already exceeded $1.9 billion (19% of all US venture capital investments made during the first half of 2010). Between 2004 and 2009, U.S. venture capital investments in energy/industrial as well as CleanTech have more than quadrupled in real terms.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2010

Protecting Intelligent Distributed Power Grids against Cyber Attacks

Like other industrial sectors, the electrical power industry is facing challenges involved with the increasing demand for interconnected operations and control. The electrical industry has largely been restructured due to deregulation of the electrical market and the trend of the Smart Grid. This moves new automation systems from being proprietary and closed to the current state of Information Technology (IT) being highly interconnected and open. However, while gaining all of the scale and performance benefits of IT, existing IT security challenges are acquired as well. The power grid automation network has inherent security risks due to the fact that the systems and applications for the power grid were not originally designed for the general IT environment. In this paper, we propose a conceptual layered framework for protecting power grid automation systems against cyber attacks. The following factors are taken into account: (1) integration with existing, legacy systems in a non-intrusive fashion; (2) desirable performance in terms of modularity, scalability, extendibility, and manageability; (3) alignment to the 'Roadmap to Secure Control Systems in the Energy Sector' and the future smart grid. The on-site system test of the developed prototype security system is briefly presented as well.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2011

Reliable algorithms for power system analysis in the presence of data uncertainties

A robust and reliable power flow analysis represents an essential requirement for many power systems applications as far as network optimization, voltage control, state estimation, and service restoration are concerned. The most common power flow approach, referred to here as a deterministic power flow (PLF), requires precise or 'crisp' values chosen by the analyst for each input variable. The solution provides precise network voltages and flows through each line. The specified values rest upon assumptions about the operating condition derived from historical measurements or predictions about future conditions and thus, cannot be considered accurate. Even in the case where the inputs are based on measurements, inaccuracies arise from time-skew problems, three-phase unbalance, static modeling approximations of dynamic components (e.g., transformer tap changers), variations in line parameters, and so on. The advent of deregulation and competitive power markets will only exacerbate this problem as well-known generation patterns change, loading becomes less predictable and the transmission paths grow more diverse. Conventional methodologies proposed in literature address tolerance analysis of power flow solution by means of detailed probabilistic methods, accounting for the variability and stochastic nature of the input data, and sampling based approaches. In particular uncertainty propagation using sampling based methods, such as the Monte Carlo, requires several model runs that sample various combinations of input values. Since the number of model runs can sometimes be very large, the required computer resources can sometimes be prohibitively expensive resulting in substantial computational demands. As far as probabilistic methods are concerned, they represent a useful tool, especially for planning studies, but, as evidenced by the many discussions reported in literature, they could reveal some shortcomings principally arising from: (1) the non-normal distribution and the statistical dependence of the input data; and (2) the difficulty arising in accurately identifying probability distributions for some input data, such as the power generated by wind or photovoltaic generators. All these could result in time consuming computations with several limitations in practical applications especially in power flow analysis of complex power networks. In order to try and overcome some of these limitations, obtaining thereby comprehensive power flow solution tolerance analysis at adequate computational costs, self validated computation could play a crucial role. Armed with such a vision, this chapter will analyze two advanced techniques for power flow analysis in the presence of data uncertainty namely the boundary power flow and the affine arithmetic power flow.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2012

On-line maintenance methodology development and its applications

With the increasing economic pressures being faced and the potential for shortening outage times under the conditions of deregulated electricity markets in the world, licensees are motivated to get an increasing amount of the on-line maintenance (OLM). The benefits of the OLM includes increased system and plant reliability, reduction of plant equipment and system material condition deficiencies that could adversely impact operations, and reduction of work scope during plant refueling outages. In Korea, allowance guidelines of risk assessment is specified in the safety regulation guidelines 16.7 and 16.8 of the Korea Inst. of Nuclear Safety (KINS), which is 'General guidelines of Risk-informed application for requesting permission of changes' and 'Requesting permission of changes of Risk-informed application for Technical Specification'. We select the emergency diesel generator (EDG) of the Ulchin unit 3 and 4 for risk assessment analysis by applying configuration changes. The EDG which has plant safety level IE belongs to on-site standby power (A, B train EDG) in electric distribution system. The EDG is important component because it should maintain standby status during plant is operating, therefore we select the EDG for target component of risk assessment analysis. The risk assessment is limited to CDF. The risk assessment is performed by using AIMS-PSA Release2. We evaluate CDF by applying the configuration changes with some assumptions. Evaluation of the full power operation and Low power/Shut down operation was performed. This study has been performed for introducing a methodology and performing risk assessment. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

To Decommission or Not To Decommission? That is the Question... Revisited

Major Highlights Comparing 1998 to 2014: Favoring Plant Shutdown: Electric utility deregulation has created greater competition; Markets have been disrupted by cheap natural gas; Despite high availability, cost of electric power from natural gas still below break-even cost of nuclear generation; Emerging ISO acceptance of fluctuating renewable energy on the grid. Favoring DECON: D and D technologies have matured; Reactor Vessel and Internals segmentation methods still being refined; Nuclear workforce is 16 years older and leaving the nuclear industry (Impact on D and D TBD); Avoiding risk of more restrictive regulation and higher LLW disposal costs. Favoring SAFSTOR: Full funding of NDT still major driver for deferring immediate dismantlement. SAFSTOR vs. near term D and D influenced by: Status of and confidence in decommissioning fund (NDT) and cost estimate; Local and state politics; Public pressure. Most early shutdown plants tend to have under-funded decommissioning funds and opt for SAFSTOR. SAFSTOR allows for fund growth through interest compounding, but must assume that cost increase is less than fund growth: May not be true across the board, Much uncertainty/risk in waste disposal costs, regulatory requirements, etc. when projected out several decades. Once initiated SAFSTOR decision is not easily changed to DECON: Plant infrastructure equipment and components not readily available, RCS chemical decontamination can be very challenging, Key/knowledgeable plant personnel are gone. Consideration for phased approach to DECON: Remove >95% of the radiological source term under today's known regulations and cost by full System Decontamination of the primary circuit systems, and removal of NSSS and decontamination of the Containment Building; Improves risk profile in those areas most vulnerable to excessive cost growth; Able to defer D and D of the remainder of the plant to allow for the NDT to grow with interest.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

Microfabricated systems and assays for studying the cytoskeletal organization, micromechanics, and motility patterns of cancerous cells

Cell motions are driven by coordinated actions of the intracellular cytoskeleton – actin, microtubules (MTs) and substrate/focal adhesions (FAs). This coordination is altered in metastatic cancer cells resulting in deregulated and increased cellular motility. Microfabrication tools, including photolithography, micromolding, microcontact printing, wet stamping and microfluidic devices have emerged as a powerful set of experimental tools with which to probe and define the differences in cytoskeleton organization/dynamics and cell motility patterns in non-metastatic and metastatic cancer cells. In this paper, we discuss four categories of microfabricated systems: (i) micropatterned substrates for studying of cell motility sub-processes (for example, MT targeting of FAs or cell polarization); (ii) systems for studying cell mechanical properties, (iii) systems for probing overall cell motility patterns within challenging geometric confines relevant to metastasis (for example, linear and ratchet geometries), and (iv) microfluidic devices that incorporate co-cultures of multiple cell types and chemical gradients to mimic in vivo intravasation/extravasation steps of metastasis. Finally, together, these systems allow for creating controlled microenvironments that not only mimic complex soft tissues, but are also compatible with live cell high-resolution imaging and quantitative analysis of single cell behavior.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Cutting planes for the multistage stochastic unit commitment problem

As renewable energy penetration rates continue to increase in power systems worldwide, new challenges arise for system operators in both regulated and deregulated electricity markets to solve the security-constrained coal-fired unit commitment problem with intermittent generation (due to renewables) and uncertain load, in order to ensure system reliability and maintain cost effectiveness. In this paper, we study a security-constrained coal-fired stochastic unit commitment model, which we use to enhance the reliability unit commitment process for day-ahead power system operations. In our approach, we first develop a deterministic equivalent formulation for the problem, which leads to a large-scale mixed-integer linear program. Then, we verify that the turn on/off inequalities provide a convex hull representation of the minimum-up/down time polytope under the stochastic setting. Next, we develop several families of strong valid inequalities mainly through lifting schemes. In particular, by exploring sequence independent lifting and subadditive approximation lifting properties for the lifting schemes, we obtain strong valid inequalities for the ramping and general load balance polytopes. Lastly, branch-and-cut algorithms are developed to employ these valid inequalities as cutting planes to solve the problem. Our computational results verify the effectiveness of the proposed approach.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2026

Change Agent: Energy Storage as a Driver of Regulatory Evolution

Purpose of Review Dividing the electric grid into the functions of generation, transmission, anddistribution enabled the drawing of jurisdictional lines and the application of the U.S.Constitution’s federalist system to energy regulation. Energy storage technologies,which can be placed throughout the grid to increase flexibility, can provide serviceacross all three of those functions. But the jurisdictional boundaries that have beendrawn around those functions have created barriers that restrict energy storagetechnologies from achieving their full potential. This review analyzes regulatory changes made to reduce barriers to storage deployment and their broader impacts on energy regulation in the U.S. Recent Findings Major energy regulations promulgated at the state and federal levels have generally focused on liberalizing the U.S. electric system through deregulation and increased competition. Paradoxically, however, these efforts have erected strict regulatory barriers that prevent energy storage technologies from providing service across multiple functions. A new wave of regulations in recent years has endeavored to reduce and remove those barriers. Summary Energy regulations adopted in recent years to reduce barriers to energy storage functionality in recent years have had deep and far-reaching impacts on U.S. electric regulation. These impacts go beyond storage and affect all energy technologies. This paper traces the development of energy regulation in U.S., the functional barriers that they created that impede energy storage functionality, recent efforts to remove those barriers, and the broader effects of those efforts. It concludes with a brief discussion of remaining barriers that prevent energy storage from reaching their full potential on the U.S. electric grid.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Design of a supervisory control system for autonomous operation of advanced reactors

Advanced reactors to be deployed in the coming decades will face deregulated energy markets, and may adopt flexible operation to boost profitability. To aid in the transition from baseload to flexible operation paradigm, autonomous operation is sought. This work focuses on the control aspect of autonomous operation. Specifically, a hierarchical control system is designed to support constraint enforcement during routine operational transients. Within the system, data-driven modeling, physics-based state observation, and classical control algorithms are integrated to provide an adaptable and robust solution. A 320 MW Fluoride-cooled High-temperature Pebble-bed Reactor is the design basis for demonstrating the proposed control system. The hierarchical control system consists of a supervisory layer and low-level layer. The supervisory layer receives requests to change the system's operating conditions (e.g., the current reactor power to meet a load -follow), and accepts or rejects them based on constraints that have been assigned. Constraints are issued to keep the plant within an optimal operating region. The low-level layer interfaces with the actuators of the system to fulfill requested changes, while maintaining tracking and regulation duties. Further, to accept requests at the supervisory layer, the Reference Governor algorithm was adopted. To model the dynamics of the reactor, a system identification algorithm, Dynamic Mode Decomposition, was utilized. To estimate the evolution of process variables that cannot be directly measured (e.g., the propagation of delayed neutron precursors), the Unscented Kalman Filter, incorporating a nonlinear model of nuclear dynamics, was adopted. The composition of these algorithms led to a numerical demonstration of constraint enforcement during a 40% power drop transient (at a rate of 5 %/min). Uncontrolled secondary-side temperatures were successfully constrained. Adaptability of the proposed system was demonstrated by modifying the constraint values, and enforcing them during the transient. Robustness was also demonstrated by enforcing constraints under noisy environments.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2021

Peer-to-Peer Energy Systems for Connected Communities: A Review of Recent Advances and Emerging Challenges

After a century of relative stability of the electricity industry, extensive deployment of distributed energy resources and recent advances in computation and communication technologies have changed the nature of how we consume, trade, and apply energy. The power system is facing a transition from its traditional hierarchical structure to a more deregulated model by introducing new energy distribution models such as peer-to- peer (P2P) sharing for connected communities. The proven effectiveness of P2P sharing in benefiting both prosumers and the grid has been demonstrated in many studies and pilot projects. However, there is still no extensive implementation of such sharing models in today’s electricity markets. This paper aims to shed some light on this gap through a comprehensive overview of recent advances in the P2P energy system and an insightful discussion of the challenges that need to be addressed in order to establish P2P sharing as a viable energy management option in today’s electricity market. To this end, in this article, we provide some background on different aspects of P2P sharing. Then, we discuss advances in P2P sharing through a systematic domain-based classification. We also review different pilot projects on P2P sharing across the globe. Finally, we identify and discuss a number of challenges that need to be addressed for scaling up P2P sharing in the electricity market followed by concluding remarks at the end of the paper.

Tushar, Wayes↗