A recent news item announces the success of a small-scale electromagnetic pulse weapon mounted in a cruise missile and used to selectively disable electronics in particular buildings. While this directed EMP generator is being developed for military purposes, imagine this weapon deployed against nuclear reactors, none of which are hardened against this sort of attack. As we saw in Fukushima, reactors which lose every source of power will self-destruct.
A nuclear HEMP (high altitude EMP) would simultaneously destroy dozens of reactors, possibly causing them to spew radioactive dust across the countryside. It’s a shame that such a reliable and self-contained source of energy has been designed with no consideration of the hazard of EMP. A high priority going forward is to choose reactor designs which are safe when all the lights go out, and which can be restarted without off-site power after replacing damaged electronics.