Transactive energy systems use principles of value to coordinate responsive supply and demand in energy systems. Work continues within the Transactive Systems Program, which is funded by the U.S. Department of Energy at Pacific Northwest National Laboratory, to understand the value of, understand the theory behind, and simulate the behaviors of transactive energy systems. This report summarizes recent advances made by this program. The main capability advances include a more comprehensive valuation model, including recommended documentation that should make valuation studies of all sorts more transparent, definition of economic metrics with which transactive mechanisms can be evaluated, and multiple improvements to the time-simulation environment that is being used to evaluate transactive scenarios. v Summary Transactive system designs are intended to drive electric system operations toward an optimal balance of supply and demand at all levels of the grid. To accomplish this, they actively seek the engagement of all potentially responsive electrical assets, including customer-owned and third-party assets, through transparent, competitive means. This provides the flexibility required by tomorrow's power grid, whether generation shifts from centralized to more distributed resources or from dispatchable generation plants to intermittent renewables. Operating such a grid, capable of powering our society by providing the reliability and affordable electricity rates it demands, necessitates new operational flexibility from resources on a large scale. In order to do this at reasonable cost, much of this flexibility is expected to be derived from distributed assets such as continually responsive loads, distributed electrical and thermal storage, smart inverters for solar photovoltaic systems, electric vehicles, etc. The U.S. Department of Energy's (DOE's) Transactive Systems Program (TSP) encourages the development of transactive designs that offer systematic, scalable, and equitable approaches for managing energy system operations. Because several designs have already been proposed, some have also been and demonstrated in the field, and more are sure to follow, the program works to inform decision makers on alternative transactive designs and their characteristics. It does this by developing a simulation environment capable of testing a variety of transactive system designs. This includes establishing a set of test scenarios with realistic models and data sets for testing such alternative transactive system designs. In addition, criteria and a disciplined process for evaluation are proposed as part of the TSP's valuation methodology element. The valuation criteria are supplemented with systemic criteria for measuring proper behavior of the transactive system being studied on topics such as scalability, optimality, and convergence. These are derived from TSP elements that contribute to a theoretical framework for transactive systems. This document reports on an early trial of the first year's progress developing an analy...

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Enabling real-time decisions on stress-relief for risk-significant equipment susceptible to degradation and damage, thereby supporting optimized lifetime management. As described in previous reports in this series, probabilistic risk assessment (PRA) provides a static representation of risk associated with operation and maintenance (O&M) of nuclear power plants. Technologies for characterizing real-time risk (so called Enhanced Risk Monitors or ERMs) take into account plant-specific normal, abnormal, and deteriorating states of systems, structures, and components (SSCs) in the estimation of current and future risk to safe and economic operation. Additionally, technologies for characterizing real-time risk provide a mechanism for compensating for the relatively small amount of long-term reliability data from AR systems, structures, and components. The ability to monitor performance and characterize changes in operational risk in real-time can reduce the level of dependence on such performance data. Proactively establishing a viable ERM methodology before AR component design specifications are established also supports: (i) building in opportunities for automated monitoring (on-line and off-line) of those components for optimizing performance with respect to anticipated demands on these reactors; and (ii) improving the maintainability of components from the perspective of time-to-repair and component cost. This research report summaries the development and evaluation of a prototypic ERM methodology (framework) that includes alternative risk metrics and uncertainty analysis. This updated ERM methodology accounts for uncertainty in the equipment condition assessment (ECA), the prognostic result, and the PRA model. It is anticipated that the ability to characterize uncertainty in the estimated risk and update the risk estimates in real-time based on ECA will provide a mechanism for optimizing plant performance while staying within specified safety margins. The report provides an overview of the methodology for integrating time-dependent failure probabilities into risk monitors. This prototypic ERM methodology was evaluated using a hypothetical PRA model, generated using a simplified design of a liquid-metal-cooled AR. Component failure data from industry compilation of failures of components similar to those in the simplified AR model were used to initialize the PRA model. By using time-dependent probability of failure (POF) that grows from the initial probability when equipment is in like-new condition to a maximum POF, which occurs before a scheduled maintenance action that restores or repairs the component to "as-new" condition, the changes in core damage frequency (CDF) over time were computed and analyzed. vii Acronyms and Abbreviations AC alternating current AdvSMR advanced small modular reactor AFI aging fractional increase AST aging start time CAFTA Computer Aided Fault Tree Analysis (system) CCF common cause failure CDF core damage frequency CREDO Centralized Reliability Data Organization (component reliabili...

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