Could you clarify why the high-power pulse counts as separate failure? Was some system meant to block high-power pulses in case of short-circuits?

Overall, withe the final point, this now looks as a much more serious system failure than Vattenfall would have us believe. As a nuclear sceptic, I'd highlight as general principles
(a) the irreducibility of the system (which makes cascading failures likely),
(b) that this cascading failure, like many others, wasn't expected and as such doesn't turn up in (prior) disaster probability calculations used in safety arguments,
(c) that such serious and multiple examples of negligence and technical bungling can occur even in countries with the best record (not the level to be expected in most places should nuclear become a global-warming-battling mainstay of electricity generation globally),
(d) that companies do some serious spinning and withholding of information (in this case, the it-wasn't-that-serious-at-all routine) even if they can expect government oversight to uncover the facts for the public some time later.

_{*Lunatic*, n.
One whose delusions are out of fashion.}