As I recall, all of our fusion warheads require a fission warhead to
generate the proper enviroment for the fusion explosion (ie enough
heat/pressure). Therefore, since a damper will render inert fission
warheads, the trigger mechinism for the fusion warhead is disabled
hence no big boom!
If, as someone suggested, you took a powerplant set for overload
and used it as a bomb that would be different. I would also be
an extremely easy target to remove from space (IMHO).
Just my 2 cents worth for what its worth.
Tony