Fission products were removed from contaminated water at Three Mile Island (TMI) by adsorbing them on mixed zeolites in stainless steel vessels. Hydrogen and oxygen gases were generated in those vessels by radiolysis of water at rates up to ∼ 70 ℓ/week. Palladium-on-alumina catalyst pellets were added remotely to each of the vessels to recombine the gases back to water and, thereby, allow safe transport and storage. After the vessels were transported to Hanford, Washington, monitoring showed that >99% of the gases were being recombined and that minor leaks allowed vessel pressures to stabilize at ∼110 kPa (16 psi) absolute. Catalyst beds were designed and built into the TMI core debris canisters to remove the hydrogen and oxygen gases expected (∼20 ℓ/week) to be generated. Tests identified appropriate catalyst types and established catalyst bed design parameters. After transport to the Idaho National Engineering Laboratory, analysts verified that hydrogen-oxygen concentrations were well below flammable limits and, therefore, were safe. Federal regulations for the transport of wastes subject to hydrogen gas generation have been established as a result of the transport of TMI wastes. Those regulations ensure nonflammable conditions by requiring that either the oxygen concentration or the hydrogen concentration remains below 5%. Those requirements appear to be appropriate. Stricter requirements to ensure that hydrogen concentrations will not exceed 5%, regardless of oxygen concentrations, would appear to be inappropriate.