Advancing Safety Standards in Nuclear Energy: Insights from the WGAMA Meeting

Introduction to the Working Group on Analysis and Management of Accidents (WGAMA)

The Working Group on Analysis and Management of Accidents (WGAMA) recently convened for a pivotal meeting focused on enhancing safety and efficiency in nuclear reactor operations. This first in-person gathering of the Task Group on the Update and Extension of the CSNI Code Validation Matrix (CCVM) took place on September 11-12, 2025, at the OECD Nuclear Energy Agency (NEA) headquarters in Boulogne-Billancourt, France. The hybrid format of the meeting allowed for participation both physically and online, accommodating a diverse group of stakeholders.

A Collaborative Spirit

Bringing together 42 participants from various institutions exemplified the commitment and collaborative spirit of the CCVM community. Attendees included experts and representatives from various regulatory bodies, research institutions, and industry stakeholders, all united by a shared vision of advancing code validation for reactor coolant systems and containment thermal-hydraulic phenomena.

Opening Remarks and Agenda Highlights

The meeting commenced with an engaging welcome speech from Fulvio Mascari, the Task Group leader from ENEA. Mascari emphasized the importance of scientific collaboration and the role of these discussions in shaping the future of nuclear safety protocols. The agenda was rich with technical presentations and discussions that offered insight into critical areas of reactor safety:

Reactor Coolant System (RCS) Topics

Led by Seok Kim from KAERI, the discussion surrounding RCS topics covered:

• Reactor Pressure Vessels: An examination of the structural integrity and materials used in construction, vital for ensuring safe operation under pressure.
• Chemistry: Insights into the chemical processes that occur within the coolant, impacting reactor efficiency and safety.
• Loops and Pumps: Detailed discussions on the machinery that circulates coolant, ensuring effective heat exchange.
• Steam Generators and Pressurizers: Analysis of systems that manage pressure and generate steam, critical for reactor operation.
• Safety Systems: Both active and passive safety measures were reviewed, underscoring the need for redundancy in safety protocols.
• Integral System Phenomena: This topic delved into how multiple systems interact during a coolant event, shaping emergency response strategies.

Containment Phenomena

Ahmed BENTAIB from ASNR chaired the session focusing on containment phenomena, which is crucial for managing any potential accidents. Key topics discussed included:

• Thermal-Hydraulics: The heat transfer processes and fluid flow that occur within the containment.
• Combustible Gas Behaviour: Understanding how gases generated during a malfunction can affect containment integrity.
• Aerosol and Fission Product Behaviour: Presentations that analyzed the transport and effects of radioactive materials in various scenarios.
• Chemistry Phenomena: Investigating how chemical reactions within containment can impact overall safety responses.

Reactor Group Sessions

Dedicated sessions on specific reactor designs offered a platform for in-depth discussions on advanced reactor types, such as:

• BWRX-300: A modern boiling water reactor that integrates advanced safety features.
• LDR-50: A design that emphasizes low power and high safety.
• BWR/ABWR: An exploration of advanced boiling water reactor technology with enhanced features for reliability.

This focus on advanced reactors reflects an ongoing commitment to improving the safety and efficiency of next-generation nuclear systems.

Summary of Actions and Future Plans

The meeting wrapped up with a thoughtful summary of actions and decisions made. Plans for continued progress were established, emphasizing the importance of in-depth technical exchanges and collaborative efforts moving forward. The collective attitude was one of optimism, as participants recognized the significant strides made in code validation for both current and advanced nuclear technologies.

This meeting not only documented the ongoing evolution in nuclear safety standards but also laid the groundwork for future collaborations. Discussions surrounding reactor coolant systems and containment phenomena are essential to ensuring that technology evolves in a safe and prudent manner.

For additional details or inquiries related to this event, stakeholders are encouraged to reach out directly to the relevant offices at the OECD Nuclear Energy Agency.