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.