I'm not too sure but I can say for certain that it doesn't spew radioactive material into the environment.

There would be some trace amounts of radioactivity in the materials used. Probably not enough to harm the public.

Similarly, most fission reactor failure modes don't release harmful amounts of contamination to the public.

Some exotic runaway condition - not sure if generators can do that - electric motors if wired incorrectly self destruct in amusing ways.

More likely you have an over speed failure and the it runs out of control and self destructs flinging the blades and other heavy objects about.