Gamma ray irradiation is the ultimate in this regard.  In Sydney,
Australia, supers (including combs) are routinely sterilised
using this process in a commercial irradiation facility used for
sterilising medical equipment.  The only requirement is that the
combs contain no honey (the honey tends to foam, for some
reason).  No doubt there will be a similar facility somewhere in
the Northwest U.S.
 
By the way, I understand that colonies introduced to irradiated
supers always perform better, at least for the first season, than
their non-irradiated counterparts.