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@ -183,45 +183,67 @@ manufacturing and other critical infrastructure.
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### Related Papers:
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[[enhancing-cyber-physical-system-dependability-via-synthesis-challenges-and-future-directions]]
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___________________________________________________________
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## **Formally Verified Runtime Monitoring and Fallback**
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### Goals:
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If this research is successful, we will be able to generate
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autonomous controller shields that provably adhere to specifications
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written with temporal logic.
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The goal of this research is to create a methodology for
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automatically generating runtime monitoring and fallback
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switching components from formal specifications in FRET for
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a reactor control system. Runtime monitoring with automatic
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switchover is a proven approach to ensuring safety in
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critical control systems: a primary controller operates
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under normal conditions, while a fallback safety controller
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is engaged if safety limits are approached or violated.
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These fallback mechanisms lend themselves naturally to
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linear temporal logic (LTL) specifications that can be
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elicited from high-level safety and operational requirements
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using automated tools. If the creation of these runtime
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monitors and switchovers can be automated from formal
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requirements, the engineering effort to implement robust
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fallback logic will be greatly reduced, while maintaining
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provable adherence to safety constraints.
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### Outcomes:
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- Create an intermediary shield that mediates signals between an
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optimal control system and the physical plant (MODBUS)?
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1. Implement reactor control safety and operational
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requirements as requirements in FRET, and extract
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temporal logic definitions of allowable system behaviors.
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- Translate specifications in a language like TLA+ into an
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executable program
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2. Synthesize the switching component from LTL specification
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using an automated tool such as Strix.
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- Provide proof artifacts that automatically generated
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shield components will not allow an arbitrary controller to
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reach an unsafe state.
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2. Develop a new endpoint for the Advanced Reactor Cyber
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Analysis and Development Environment (ARCADE) that
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utilizes a shielding mechanism to switch between control
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trains.
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3. Create an example learning-based controller to
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demonstrate the application of the machine generated
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shield.
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4. Provide proof artifacts that automatically generated
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shield components will not allow an arbitrary controller
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to reach an unsafe state.
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### Impact:
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Shielding is one of the preeminent ways to do safe machine
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learning controllers. Instead of putting the proof burden on
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the machine learning component, shielding creates a safe
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boundary in the state space where a safety controller will
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step in if the machine learning controller endangers the
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system. This technology solves a critical problem with high
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assurance systems: high assurance systems have critical
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safety requirements that make scrutiny on autonomous systems
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safety intense. Shielding can provide a safety barrier for
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the controller, allowing the architecture of the control
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laws to be amenable to more efficient machine learning based
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methods. Finally, utilizing an automatic translation from a
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temporal logic formulation of a speculation will allow the
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engineers of these systems to quickly and clearly implement
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a shield, without all of the cumbersome derivation.
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This approach addresses a persistent challenge in
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high-assurance systems: stringent safety requirements often
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force engineers to trade innovation and adaptability for
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proven but rigid safety mechanisms. The proposed method
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maintains safety guarantees while allowing more flexible or
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advanced primary control strategies. Moreover, automating
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the translation from formal safety requirements into
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executable monitoring and switchover logic creates a
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repeatable, transparent, and verifiable process. This
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reduces engineering effort, improves traceability to
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regulatory requirements, and may enable faster deployment of
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safety-critical control architectures in nuclear power and
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other critical infrastructure systems.
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### Related Papers:
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@ -232,67 +254,67 @@ a shield, without all of the cumbersome derivation.
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___________________________________________________________
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## **Data-Driven Fault Detection Using High-Assurance Digital Twins**
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(8)
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### Goals:
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The goal of this research is to use machine learning to
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identify system faults of a reactor control system during
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runtime. A digital twin will be compared to measurements
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from a real plant to identify issues such as coolant losses,
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sensor and actuator failures, or component degredation so
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that safety strategic decisions about the plant can be made
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autonomously.
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The goal of this research is to develop a high-assurance,
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digital twin–based methodology for runtime fault detection
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in a reactor control system. A physics-based digital twin
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will be continuously compared with live plant measurements
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to detect anomalies such as coolant losses, sensor and
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actuator faults, and abnormal component degradation. Discrepancies
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between the digital twin and plant data will be analyzed
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using physics-informed machine learning models to diagnose
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the underlying fault and trigger appropriate autonomous
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control actions.
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### Outcomes:
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For this research to be successful, I will accomplish the
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following:
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- Create a simulation suite for the Small Modular Advanced
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High Temperature Reactor (SmAHTR) to simulate fault
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conditions of sensors, actuators, and component degradation.
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1. Create a simulation suite for the Small Modular Advanced
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High Temperature Reactor (SmAHTR) to simulate fault
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conditions including sensor and actuator failures, and
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component degradation.
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- Develop a physics informed neural network (PINN) approach
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to evaluate physics discrepancies in measured signals and
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to estimate physically relevant parameters to determine
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real system divergence from the nominal plant.
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2. Implement a physics-informed neural network (PINN)
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framework to estimate key plant parameters, detect
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discrepancies between predicted and measured signals, and
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identify probable fault conditions.
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- Realize a proof of concept autonomous controller than can
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react to fault conditions by switching to different
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control modes rather than only responding with reactor
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shutdown.
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3. Integrate the fault detection developed with a
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proof-of-concept autonomous supervisory controller
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capable of implementing graded responses to fault
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conditions.
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### Impact:
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The nuclear energy industry's largest expense is operations
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and maintenance (O&M). These costs include typical reactor repair
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and refueling, the labor involved to complete such
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and maintenance (O&M). These costs include typical reactor
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repair and refueling, the labor involved to complete such
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maintenance, and finally the labor involved in operating the
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reactor itself. Currently the largest of these O&M expenses
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is the labor and part cost used in maintenance, while large
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nuclear reactor facilities require a modest reactor operator
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budget per megawatt of energy produced. The advent of small
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modular reactors (SMRs) and microreactors (MRs) will change
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these economics significantly.
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reactor itself. Large reactors are able to spread these O&M
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costs over large power outputs, but small modular reactors
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(SMR) and microreactors (MR) do not have the same capacity
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to dissipate O&M costs. Instead, SMRs and MRs must innovate
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in O&M to be economically competitve. As SMRs and MRs become
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more common, the cost of repair and maintenance will reduce
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dramatically as nuclear power components become modular,
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replaceable parts instead of the bespoke reactor designs
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currently operating in large reactors. Operator wages,
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however, can be expected to increase without introducing
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greater controller autonomy. SMRs and MRs have much smaller
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power output per reactor core, and if they are required to
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employ the same size reactor operator team as a conventional
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large reactor, will suffer from much larger operator expense
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per megawatt. Greater controller autonomy can solve this
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problem by unloading some reactor control responsibilities
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from the operator, and therein reduce labor cost.
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As SMRs and MRs become more common, the cost of repair and
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maintenance should reduce dramatically as nuclear power
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components will become modular, replaceable parts instead of
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the bespoke reactor designs currently operating. Operator
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wages, however, can be expected to increase without
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introducing greater controller autonomy. SMRs and MRs are
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much smaller output designs per reactor core, and if they
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are required to employ the same size reactor operator team
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as a conventional large reactor, will suffer from much
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larger operator expense per megawatt. Greater controller
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autonomy can solve this problem by unloading some reactor
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control responsibilities from the operator, and therein
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reduce labor consumption.
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<# TO DO #>
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Finally reactor safety can be improved by greater autonomy
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yada yada find some reasons to back this up.
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(I think something can be said about safety here too (time
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to respond, human factors removed, etc.), but I'm chewing on
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how to word that.)
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### Related Papers:
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___________________________________________________________
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