With a VEI 6 happening there, a lil' bit of radioactivity would be one of your lesser problems, I'd guess. One bigger potential problem would be damming the Rhi

With a VEI 6 happening there, a lil' bit of radioactivity would be one of your lesser problems, I'd guess. One bigger potential problem would be damming the Rhine there, and flooding large areas behind that dam way upstream, with many large chemical plants. And then the flood downstream, if that dam breaks down.