Dynamic modelling of power cycles for Small Modular Reactors

Abstract

Small Modular Reactors (SMRs) present a transformative approach to nuclear energy, offering enhanced cost-effectiveness and ease of implementation compared to traditional large-scale reactors. This study investigates the dynamic behavior of the steam cycle within SMRs using Simscape MATLAB for simulation. The research focuses on understanding the thermodynamic principles and fluid dynamics that govern the steam cycle in these reactors. By modeling the interaction between the turbine, condenser, and pump, the study aims to evaluate the performance and safety of SMRs.

The simulation model was developed by initially creating individual component models to understand their behavior. These models were then integrated into a complete system, simulating various operational scenarios. Special attention was given to the initialization of variables to ensure convergence, which is crucial for accurate simulations. Subsequently, a second boiler was added in parallel to study the scenario of two SMRs operating simultaneously and connected to a single turbine. Using this model, pressure drops were simulated with granular intervals to study their effects on system stability and performance. The impact of varying heat flow in one of the boilers, representing increased heat generation by the SMR, and the variation of mass flow imposed on the turbine were also analyzed.

Findings reveal significant instability with the addition of a second boiler, primarily due to complexities in mass flow distribution and mass balance equations. These instabilities are further exacerbated by abrupt changes in mass flow, emphasizing the need for careful flow rate management. Additionally, increasing the heat flow leads to higher values across the system, including pressures, temperatures, and internal energy. On the other hand, optimizing mass flow significantly enhances system efficiency, as demonstrated by notable improvements in mechanical power generation when the mass flow is reduced.

Popular Abstract

Exploring the Future of Nuclear Energy with Small Modular Reactors

One of the most critical goals for protecting our planet's ecosystem is generating energy without emitting carbon dioxide (CO2). Nuclear energy stands out as a prime candidate for this mission since it doesn't produce CO2 during operation. Among the various nuclear technologies, Small Modular Reactors (SMRs) are emerging as a more economical and flexible alternative to traditional large nuclear reactors. Their smaller size, enhanced safety features, and versatile installation options make them a promising solution for sustainable energy.

This study delves into the steam cycle of SMRs, employing advanced simulations using Simscape MATLAB to unravel the intricate processes within these systems. The steam cycle is pivotal for converting the heat produced by nuclear reactors into electrical energy, and it comprises four main components: the boiler, turbine, condenser, and pump.

To push the boundaries of current models, we introduced a second boiler running in parallel with the first, simulating two SMRs feeding a single turbine. This innovative configuration aims to enhance space efficiency, profitability, and control within a nuclear power plant. However, this model presents unique challenges, as it is not commonly studied. The primary goals are to assess the feasibility of combining two boilers with one turbine and to ensure system safety.

Key Findings and Challenges

The study examined various variables to evaluate the system's viability, including the pressure drop between the boilers and the turbine, the amount of heat generated by the reactors, and the volume of steam circulating through the system. The key findings were:

System Instability: Adding a second boiler made the system more complex and unstable, complicating predictions and raising safety concerns.
Increased Heat Generation: Raising the heat output from the reactors resulted in higher values throughout the system, indicating a need for more precise control mechanisms.

This study underscores the complexities and potential of integrating multiple boilers in SMRs to improve nuclear power plant efficiency. While the innovative model shows promise, it also highlights the need for further research and advanced control systems to ensure safety and stability. Exploring these configurations can lead to more efficient and sustainable nuclear energy solutions, significantly contributing to our global environmental goals.

• author: Antón Rábade, Elena Covadonga
• supervisor: Marcus Thern
• organization: Department of Energy Sciences
• course: MVKM01 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Small Modular Reactors, steam cycle, Simscape, dynamic behavior, two-boilers, mass flow distribution, pressure drop, system efficiency
• report number: LUTMDN/TMHP-20/5456-SE
• ISSN: 0282-1990
• language: English
• id: 9170183
• date added to LUP: 2024-07-04 18:14:16
• date last changed: 2024-07-04 18:14:16