Development of Dynamic Safety Assessment Instruments for Application to Nuclear Power Plant Risk-Informed Methods

Abstract

In the field of nuclear energy, ensuring the safety of reactors is a top priority. Traditional safety assessments rely on static models that do not fully capture the complexity of real-world accidents. To address this, a new method called Dynamic Probabilistic Safety Assessment (D-PSA) is being developed and applied to modern nuclear reactor designs. D-PSA enhances safety analysis by dynamically simulating how reactor systems interact and evolve during accident scenarios, providing more accurate risk assessments. This work focuses on applying D-PSA to CANDU reactors, a type of nuclear power plant used in Canada and around the world. CANDU reactors have unique features, such as using heavy water as a coolant and moderator, making safety analysis particularly complex. By applying D-PSA to potential CANDU reactor accidents, system behaviour can be modeled more realistically, including how operators and safety systems respond in real time. In parallel, the research also explores the validation of thermal-hydraulic codes—software used to simulate fluid flow and heat transfer in nuclear reactors. For this purpose, the thermal-hydraulic code ASYST4.1 is applied to assess the behavior of small modular reactors (SMRs), a new generation of nuclear reactors designed to be smaller, safer, and more flexible. By validating this code for SMRs, researchers can improve the accuracy of simulations in future studies. The combination of D-PSA with thermal-hydraulic code validation offers a powerful approach to improving nuclear safety. In future research, using both methods together will provide better insights into how reactors behave during accidents and help develop more robust safety measures. This work aims to advance nuclear safety methodologies for both existing reactors like CANDU and future designs like SMRs, ensuring safer and more reliable energy generation.