According to the Periodic Safety Review Process, the safety level is re-assessed every ten years, considering national and international operational feedback, evolution of knowledge and best available practices. Protection against natural hazards is part of this safety level re-assessment. In the current global change context, climate change impact has to be integrated in external natural hazards estimations, such as climatic hazards or external flooding.
EDF has consequently implemented a climate watch approach. Undertaken approximately every 5 years, roughly in line with the publication of the assessment reports of the Intergovernmental Panel on Climate Change (IPCC) and with the update of safety licensing basis during Periodic Safety Reviews, this approach is intended to:
- revisit the climatic hazards which present a plausible or certain upward trend, and could lead to an increased reference hazard level,
- monitor the reach of target levels which should trigger a thorough analysis (concept of Major Climate Event) to ensure the robustness of the reference hazard level between two periodic reviews.
This climate watch approach is developed in partnership with the scientific community and is based on the following activities:
- compile and analyze datasets on hazards that are subject to changes with climate change (observed and modelled time series),
- develop knowledge of associated climatic phenomena (models, projections).
The application of this approach is presented in two steps:
- the key implications of the last climate watch exercise carried out in 2015, which identified climatic hazards whose evolution is unfavorable and is plausible or certain for the sites of EDF NPPs:
○ High air and water temperatures (for the “heat wave” hazard)
○ Sea level (for the “external flooding” hazard for coastal or estuary sites)
○ Drought or « low flow » hazard for fluvial sites;
- the results obtained for the 900 MW units, for which EDF started the 4th periodic safety review in 2019.
Such an approach, which is closely linked to periodic reviews, ensures the robustness of nuclear power plants to the climatic hazards through the consideration of the updated hazard levels.