Nuclear Waste Policy Act - Repository Closure

Repository Closure

Current repository closure plans require backfilling of waste disposal rooms, tunnels and shafts with rubble from initial excavation and sealing openings at the surface, but do not require complete or perpetual isolation of radioactive waste from the human environment. Current policy relinquishes control over radioactive materials to geohydrologic processes at repositiory closure. Existing models of these processes are empirically underdetermined, meaning there is not much evidence they are accurate. DOE guidelines contain no requirements for permanent offsite or onsite monitoring after closure. This may seem imprudent considering repositories will contain millions of dollars worth of spent reactor fuel which might be reprocessed and used again either in reactors generating electricity, in weapons applications, or possibly in terrorist activities. Technology for permanently sealing large-bore hole walls against water infiltration or fracture does not currently exist. Previous experiences sealing mine tunnels and shafts have not been entirely successful, especially where there is any hydraulic pressure from groundwater infiltration into disturbed underground geologic structures. Historical attempts to seal smaller bore holes created during exploration for oil, gas and water are notorious for their high failure rates, often in periods less than 50 years.