Nuclear power plants are highly complex systems that must integrate diverse engineering domains to produce electricity safely and efficiently. The system-level challenge addressed in this project is the optimization of a nuclear power plant design to achieve maximum efficiency and cost-effectiveness while meeting strict safety, thermal, regulatory, and environmental constraints.
The nuclear power plant is decomposed into three major interacting subsystems:
The Nuclear Reactor, which generates thermal energy via nuclear fission.
The Power Conversion System, which transforms thermal energy into usable electrical energy
The Cooling System, which dissipates waste heat to the environment.
These subsystems are physically coupled - e.g., the thermal output from the reactor becomes input to the turbine system and must be balanced by the cooling tower’s heat rejection capacity. We also chose the MAGNATEX® MAXP A85-10 industrial water pump to move coolant between our systems. The system optimization seeks to coordinate these components to minimize the cost per unit energy output while respecting engineering feasibility, regulatory limits, and safety constraints.
The plant is modeled as a system of interconnected, constrained nonlinear optimization problems, one for each subsystem. Each subsystem focuses on a specific physical function:
The Nuclear Reactor is modeled using nuclear reaction physics and thermodynamic principles, where the goal is to maximize heat generation per unit mass of fuel. Regulatory and physical constraints such as fuel enrichment limits, neutron flux levels, and core volume bounds are strictly enforced.
The Power Conversion System (partially modeled) likely involves a steam Rankine cycle where turbine efficiency is a function of pressure, temperature, and system design. It determines how much thermal energy is converted into electrical energy.
The Cooling System is modeled with a mix of empirical and theoretical fluid dynamics equations to simulate spray-cooling, natural and forced air convection, and heat dissipation. The aim is to maximize cooling per dollar spent on energy and land costs.
Optimization is performed using MATLAB’s fmincon with the Sequential Quadratic Programming (SQP) algorithm, suitable for nonlinear problems with bound and constraint enforcement. This modular approach allows independent tuning of each subsystem while ensuring integrated system feasibility.
The optimization involves a set of tightly coupled decision variables, constraints, and performance outputs across subsystems:
Key Relationships:
Higher fuel enrichment improves energy density but increases cost, and must stay within legal bounds.
Larger reactor cores improve output but increase complexity and structural costs.
Stronger neutron flux raises power, but must be balanced by cooling capability.
Higher fan power boosts cooling but reduces net electrical output and increases cost.
More sprayers and larger sprayer areas improve cooling but raise land costs.
These variables are tuned to maintain system feasibility while minimizing the objective function. The integrated model ensures energy balance and cost-efficiency across the full plant lifecycle.
Method:
Perturb each decision variable from the optimized values
Re-optimize or evaluate the change in fmin (net earnings per joule)
Most Sensitive Variables:
Fuel Enrichment (fuel): Increasing efuel beyond 0.03 significantly raises fuel cost and violates safety limits without meaningful thermal gain.
Coolant Sprayer Nozzles (#): Limiting the number of nozzles directly impacts the size of the reactor.
Constraint Most Binding: Reactor power constraint
Many solutions approach the 5000 MW cap; increasing thermal output beyond this invokes a penalty, influencing all downstream systems (conversion and cooling).
Real-World Implications:
Fuel enrichment must be tightly regulated for both cost and safety.
Reactor power limits drive the design of conversion and cooling systems, emphasizing integrated regulatory compliance and system coordination.
Relevance:
The final design provides feasible, cost-effective, and regulation-compliant performance while maximizing economic yield.
Model Fidelity:
Each subsystem incorporates realistic physical laws (e.g., thermodynamics, fluid dynamics), and the system model preserves coupling and economic integration.
Example: Cooling load is driven by waste heat, which is a direct function of reactor output and conversion efficiency — this link is respected throughout.
Software:
MATLAB’s fmincon with the interior-point algorithm
Used for its capability to handle high-dimensional, nonlinear, constrained problems
Validated across 5 trials for consistency and robustness
Implications:
Subsystem optimization can mislead designers by ignoring interdependencies, e.g., maximizing η_turbine alone ignores cooling costs.
System-level optimization provides a holistic trade-off between technical feasibility and economic performance, critical in high-capital infrastructure like nuclear power.