It only fully plays on locally, under a unique (national) certification authority. Historically each nation nuclear certification authority developed its own s

It only fully plays on locally, under a unique (national) certification authority. Historically each nation nuclear certification authority developed its own set of requirements. There are links, and a push to federate efforts, however it remains true. Case in point: the Olkiluoto-3 EPR reactor isn't exactly the same as Flamanville-3, the one being built in France, because the Finns wanted/needed various different thingies. Any of such requirement may have a significant impact on the design, and therefore impede the SMR approach.