Snarky answer: It's simple, they are just going to build the final storage on the border to Germany. Then it will be their problem when it starts leaking.
In fact, I think this is one of the main reasons that will make the widespread use of nuclear energy possible: once your neighbor have built a reactor, you begin to share with them all the risks associated with nuclear energy, but you receive none of the benefits. This makes building a nuclear reactor more attractive to you, since you're already bearing the risks.