11 KiB
Thesis Ideas 2025-07-30
Following our group meeting from Monday, July 28th, Dan suggested I write down 6 ideas, and from them we shall figure out a possible topic idea that I can really start working on.
I used ChatGPT to do some of the heavy lifting based on the papers I've been reading, and leveraged the 'deep research' feature. Here are some of my favorite ideas, broken down into goals, outcomes, impact, and related papers.
Integrating Shielding into Nuclear Power Control
Goal:
The goal of this research is develop machine learning enabled control algorithims for nuclear power applications that incoporate shielding: a formal guarantee of adherence to system specifications without augmenting the machine learning process.
Outcomes:
For this research to be successful, I will accomplish the following:
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Identify key controllers in a nuclear power context with the most benefit from using an ML-based controller
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Translate regulatory and system level requirements into a formal specification to synthesize a controller 'shield'. This shield monitors the ML controller and intervenes whenever a requirement is predicted to be violated.
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Evaluate performance of the ML controller with attached shield, while assessing the amount of shield useage for different operating scenarios (power up, shut down, regular load following)
Impact:
Machine learning controllers can outperform PID and rule-based controllers by adapting to nonlinear dynamics, optimizing over multi-objective cost functions, and changing plant conditions. But, these ML controllers are often unexplainable, meaning that their global behavior is not easily understood.This unexplainability prevents ML based controllers from being used in high-assurance usecases such as nuclear power. Shielding can address this issue, by providing a formal runtime assurance, allieviating the burden of explainability away from the machine learning algorithm. This work would further bring regulatory requiremnts into the formal design of control systems and help bridge the gap between high assurance systems and the start of the art in control.
Relevant Papers
safe-reinforcement-learning-via-shielding evaluating-robustness-of-neural-networks-with-mixed-integer-programming
Formally Verified Neural Network Control of Control Rod System
Goals:
The goal of this research is to use formal methods to ensure that a neural network based control rod controller will never violate safety guarantees of a reactor trip system. To do this, a satisfiability modulo theory method will be applied to exhaustively search the network for potential failure modes.
Outcomes:
If this research is successful, I will have accomplished the following:
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Build a neural network controller for real time control of a control rod system.
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Formalize safety guarantees of shutdown margin in a satisfiability modulo theory embedding
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Formally verify that the neural network based controller will not violate any shutdown margin restrictions
Impact:
SMT solvers and MILP formulations have been applied to neural networks to ensure that the network is resilient to input perturbations. I think we can expand this to more general considerations of the state space, especially when there are a relatively small number of states such as in power contexts. The benefit of this system is that we would get closer to saying neural network based systems can be high assurance for physical systems.
Related Papers:
reluplex-an-efficient-smt-solver-for-verifying-deep-neural-networks evaluating-robustness-of-neural-networks-with-mixed-integer-programming formal-verification-of-neural-network-controlled-autonomous-systems
Temporal Logic Specifications for Autonomous Controller Synthesis
Goals:
The goal of this program is to use temporal logic specifications to procedurally generate autonomous supervisory controllers for a reactor system.
Outcomes:
If this research is successful, I will have accomplished the following:
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Captured high level safety and operating requirements in a temporal logic language such as TLA+ or FRET
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Synthesize a supervisory controller from the temporal logic specification that can be implemented on a real control system with minimal user effort.
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Verify the supervisory controller generated adheres to safety specifications using exhaustive model checking.
Impact:
Related Papers:
Formally Verified Runtime Monitoring and Fallback
Goals:
If this research is successful, we will be able to generate autonomous controller shields that provably adhere to specifications written with temporal logic.
Outcomes:
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Create an intermediary shield that mediates signals between an optimal control system and the physical plant (MODBUS)?
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Translate specifications in a language like TLA+ into an executable program
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Provide proof artifacts that automatically generated shield components will not allow an arbitrary controller to reach an unsafe state.
Impact:
Shielding is one of the preeminent ways to do safe machine learning controllers. Instead of putting the proof burden on the machine learning component, shielding creates a safe boundary in the state space where a safety controller will step in if the machine learning controller endangers the system. This technology solves a critical problem with high assurance systems: high assurance systems have critical safety requirements that make scrutiny on autonomous systems safety intense. Shielding can provide a safety barrier for the controller, allowing the architecture of the control laws to be amenable to more efficient machine learning based methods. Finally, utilizing an automatic translation from a temporal logic formulation of a speculation will allow the engineers of these systems to quickly and clearly implement a shield, without all of the cumbersome derivation.
Related Papers:
on-using-real-time-reachability-for-the-safety-assurance-of-machine-learning-controllers enhancing-cyber-physical-system-dependability-via-synthesis-challenges-and-future-directions safe-reinforcement-learning-via-shielding
Data-Driven Fault Detection Using High-Assurance Digital Twins
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Goals:
The goal of this research is to use machine learning to identify system faults of a reactor control system during runtime. A digital twin will be compared to measurements from a real plant to identify issues such as coolant losses, sensor and actuator failures, or component degredation so that safety strategic decisions about the plant can be made autonomously.
Outcomes:
For this research to be successful, I will accomplish the following:
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Create a simulation suite for the Small Modular Advanced High Temperature Reactor (SmAHTR) to simulate fault conditions of sensors, actuators, and component degradation.
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Develop a physics informed neural network (PINN) approach to evaluate physics discrepancies in measured signals and to estimate physically relevant parameters to determine real system divergence from the nominal plant.
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Realize a proof of concept autonomous controller than can react to fault conditions by switching to different control modes rather than only responding with reactor shutdown.
Impact:
The nuclear energy industry's largest expense is operations and maintenance (O&M). These costs include typical reactor repair and refueling, the labor involved to complete such maintenance, and finally the labor involved in operating the reactor itself. Currently the largest of these O&M expenses is the labor and part cost used in maintenance, while large nuclear reactor facilities require a modest reactor operator budget per megawatt of energy produced. The advent of small modular reactors (SMRs) and microreactors (MRs) will change these economics significantly.
As SMRs and MRs become more common, the cost of repair and maintenance should reduce dramatically as nuclear power components will become modular, replaceable parts instead of the bespoke reactor designs currently operating. Operator wages, however, can be expected to increase without introducing greater controller autonomy. SMRs and MRs are much smaller output designs per reactor core, and if they are required to employ the same size reactor operator team as a conventional large reactor, will suffer from much larger operator expense per megawatt. Greater controller autonomy can solve this problem by unloading some reactor control responsibilities from the operator, and therein reduce labor consumption.
<# TO DO #> Finally reactor safety can be improved by greater autonomy yada yada find some reasons to back this up.
Related Papers:
Verified Adaptive Control
Goals:
The goal of this research is to create an adaptive controller that can adjust to system dynamics changes over time to maintain an optimal control, while using formal methods to provide strong safety guarantees about the malleable control law.
Outcomes:
For this research to be successful, I will accomplish the following:
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Create a simulation suite for the Small Modular Advanced High Temperature Reactor (SmAHTR) to simulate component degradation such as heat exchanger blockages and fuel concentration burn-up.*
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Create an adaptive control rod controller to maximize load following precision for a simulated power grid demand.
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Use contract based verification at runtime to ensure that learned parameters for the adaptive controller remain within safety specification limits
*Is this actually even a problem for SmAHTR? Figuring the fuel is suspended in the salt I'd assume chemistry is pretty strictly controlled. I'm sure I can find other examples.
Impact:
Certain reactor control systems are already automatic systems, such as constant temperature or pressure controls for operating at steady state. These simple controllers are able to follow load changes from the power grid on their own, but over will lose efficiency as the underlying plant mechanics become less efficient, or maintenance is performed and components are refreshed. For nuclear power contexts, fine control is ideal to maximize profits and to minimize energy wasteage. This is not an easy problem to solve, however, as the dynamics of the underlying plant are constantly changing. Adaptive control can help address this issue, but learnable controllers must come with guarantees of safety in order to be attractive to the nuclear industry.