Nuclear Energy Agency (NEA) – Preventing, mitigating and managing potential accidents at nuclear power plants

Nuclear Energy Agency (NEA) – Preventing, mitigating and managing potential accidents at nuclear power plants

The NEA Working Group on Accident Analysis and Management (WGAMA) held its annual meeting in person September 11-13, 2023 to discuss its ongoing work and activities related to potential accident situations at nuclear power plants. The meeting included more than 80 delegates from 20 member states, as well as representatives of the International Atomic Energy Agency and the European Commission.

The working group aims to evaluate and strengthen the technical basis necessary to prevent, mitigate and manage potential accidents in nuclear power plants. It also facilitates international cooperation in incident management and strategies. In this context, the group currently focuses on three main areas: nuclear thermal hydraulics, and computational fluid dynamics (CFD) for nuclear reactor safety and serious accidents.

During the meeting, participants discussed the 14 Group’s ongoing activities in the three main areas with the aim of assessing progress and determining next steps.

One of the main questions discussed was how to progress the CSNI Code Validation Matrix (CCVM). Conducting safety assessments using T/H safety analysis codes is essential for the safe operation of nuclear power plants. Hence, several CCVMs have been set up to ensure that codes are validated with a large amount of appropriate experimental data, which may cover reactor accident responses specific to the reactor design. Validation matrices were generated for the integrated effect tests and separate effects tests. It was later supplemented for VVER reactor phenomena and severe incidents, such as disintegration and containment phenomena within the ship. Reaching consensus that these matrices constitute a generally recognized dataset for code validation was a major accomplishment for the group. Once expected accident conditions are included in the SAM and the relevant database scopes are created to properly address advanced reactor designs, the SAM should become a real asset for analytical instrument development and validation. This rigorous approach should also be necessary for evolutionary and innovative reactor designs, including small and medium reactors. WGAMA recommends that a CCVM be established or updated specifically for the reactor design of interest to avoid any deficiency in safety assessment, based on reactor prototype case tests and/or appropriately sized simulation experiments.

The group also discussed proposals for three potential new activities: a new workshop on experimental validation and application of CFD and CMFD codes to nuclear reactor safety issues (CFD4NRS-10); Seminar on transfer of thermo-hydraulic knowledge acquired through CSNI activities (THICKET-5) and the International Standards Problem (ISP) based on IRSN coal reflooding experiments.

A highlight of the meeting will be the session dedicated to the IAEA’s nuclear safety research pilot activities, including the next phase of Fukushima Daiichi Nuclear Power Plant accident information collection and evaluation (FACE). The group agreed to support new joint projects on filtration studies on distinct SA-damaged heart samples (Lisak) and the thermal hydraulic system (Sister). SYSTHER is an attempt to create a platform to address thermonuclear and hydraulic safety priorities, for both current and advanced reactor designs, including small and medium reactors.

The direction of the next WGAMA meeting will be shaped by input gathered from participants and through collaboration with international organizations and other NEA groups.

For more information about the task force, click here.

    (Tags for translation)Nuclear Safety

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