Michael David Muhlheim

Nuclear Generating Stations and Transmission Grid Reliability

Nuclear generating stations have historically been susceptible to transmission system voltage excursions. When nuclear generating stations trip because of voltage excursions, the resulting loss in real and reactive power support can exacerbate transmission events. New standards are being developed which should help improve nuclear plant and transmission system reliability. This paper provides a brief historical perspective. Nuclear plants do not provide automatic generation control in response to frequency decay and are also limited in providing voltage support. As 28 new nuclear plants are being considered for connection to an already highly stressed transmission grid, consideration must be given to nuclear plant design features that will enhance transmission system reliability.

Development of an Automated Decision-Making Tool for Supervisory Control System

This technical report was generated as a product of the Supervisory Control for Multi-Modular Small Modular Reactor (SMR) Plants project within the Instrumentation, Control and Human-Machine Interface technology area under the Advanced Small Modular Reactor (AdvSMR) Research and Development Program of the US Department of Energy. The report documents the definition of strategies, functional elements, and the structural architecture of a supervisory control system for multi-modular AdvSMR plants. This research activity advances the state of the art by incorporating real-time, probabilistic-based decision-making into the supervisory control system architectural layers through the introduction of a tiered-plant system approach. The report provides background information on the state of the art of automated decision-making, including the description of existing methodologies. It then presents a description of a generalized decision-making framework, upon which the supervisory control decision-making algorithm is based. The probabilistic portion of automated decision-making is demonstrated through a simple hydraulic loop example.

Initiating Events for Multi-Reactor Plant Sites

Inherent in the design of modular reactors is the increased likelihood of events that initiate at a single reactor affecting another reactor. Because of the increased level of interactions between reactors, it is apparent that the Probabilistic Risk Assessments (PRAs) for modular reactor designs need to specifically address the increased interactions and dependencies.

Common-Cause Failure Mitigation Practices and Knowledge Gaps

This technical report documents the findings from first phase of research activities by ORNL. Specifically, the report describes the results of the investigation of CCF mitigation practices and determination of knowledge gaps.

DEVELOPMENT OF A SUPERVISORY CONTROL SYSTEM CONCEPT FOR ADVANCED SMALL MODULAR REACTORS

Small modular reactors (SMRs) can provide the United States with a safe, sustainable, and carbon-neutral energy source. Because of their small size and, in many cases, simplified nuclear island configurations, it is expected that capital costs will be less for SMRs compared to that of large, Generation III+ light-water reactors. Advanced SMRs (AdvSMRs), which use coolants other than water as the primary heat transport medium, introduce several passive safety concepts and controls features that further reduce the complexity of primary system designs by eliminating redundant components and systems.Under U.S. Department of Energy (DOE) Office of Nuclear Energy (NE), the Supervisory Control of Multi-Modular SMR Plants project was established to enable innovative control strategies and methods to supervise multi-unit plants, accommodate shared systems, identify opportunities to increase the level of automation, define economic metrics based on the relationship between control and staffing levels, and permit flexible co-generation operational regimes.This paper documents current findings from the Supervisory Control project. Specifically, it defines and documents strategies, functional elements, and an architectural structure for supervisory control of a representative generic AdvSMR plant. More specifically, this research advances the state-of-the art by incorporating decision making into the supervisory control system architectural layers through the introduction of tiered taxonomy of plant systems and subsystems.The proposed architecture has the features of planning and scheduling, analyzing plant status, diagnosing problems as they develop and predicting potential future problems, making decisions based on these features, and generating validated commands to lower control layers in the architecture.Copyright

Supervisory Control System Architecture for Advanced Small Modular Reactors

This technical report was generated as a product of the Supervisory Control for Multi-Modular SMR Plants project within the Instrumentation, Control and Human-Machine Interface technology area under the Advanced Small Modular Reactor (SMR) Research and Development Program of the U.S. Department of Energy. The report documents the definition of strategies, functional elements, and the structural architecture of a supervisory control system for multi-modular advanced SMR (AdvSMR) plants. This research activity advances the state-of-the art by incorporating decision making into the supervisory control system architectural layers through the introduction of a tiered-plant system approach. The report provides a brief history of hierarchical functional architectures and the current state-of-the-art, describes a reference AdvSMR to show the dependencies between systems, presents a hierarchical structure for supervisory control, indicates the importance of understanding trip setpoints, applies a new theoretic approach for comparing architectures, identifies cyber security controls that should be addressed early in system design, and describes ongoing work to develop system requirements and hardware/software configurations.