ASN said in a statement on Thursday that while the overall design of the new EPR 2 seemed to be safe, EDF would have change certain elements for it to be approved, notably the break-preclusion concept for its cooling circuit.
In initial talks with the ASN, EDF had proposed to design the new EPR 2’s cooling circuit pipes with the same “rupture exclusion” concept as in the existing EPR, which is under construction at Flamanville in France, Olkiluoto in Finland and Hinkley Point in England.
This means that components – notably pipes in the primary and secondary circuits – are manufactured to such a high standard that rupture is ruled out and the manufacturer does not have to plan for what to do in case of accident.
According to ASN the rupture exclusion concept allows the operator “not to fully study the consequences of a rupture of these pipes in the safety demonstration of the installation”.
This rupture exclusion concept has shown its limits at the EPR under construction in Flamanville, where badly executed weldings on the main steam lines will lead to new delays and extra costs.