ASN considers that EDF’s planned break preclusion approach for the EPR2 reactor is acceptable

ASN considers that using a break preclusion approach for the main lines of the primary and secondary systems of the EPR 2 project is acceptable. This position supplements ASN’s 2019 opinion on the safety options of this reactor project.

As with the EPR reactor, EDF intends to apply a break preclusion approach to its new EPR 2 reactor model. The principle of this approach as applied to lines consists in the nuclear safety case not considering the consequences of a line rupture because this rupture is made highly improbable with a high degree of confidence. It is underpinned by particularly stringent measures in terms of the design, manufacture and in-service monitoring of these lines.

In 2019, ASN considered that the choice of a break preclusion approach for the EPR 2 reactor had not been sufficiently substantiated and that EDF needed to define the options selected for the design, manufacture and in-service monitoring of the lines concerned.

Since then, EDF has supplemented its file and intends to make a number of design, manufacturing and organisational changes to enhance safety. These changes will more particularly concern the choice of materials and manufacturing and inspection techniques. Furthermore, even though EDF applies a break preclusion approach, it also intends to add certain devices to mitigate the consequences of any break, such as separating walls, whip-restraint devices and steam evacuation vents.

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