Used Fuel Deep Geological Repository Shaft Versus Ramp Trade-off Study

Abstract

The current reference design for the Adaptive Phase Management (APM) deep geological repository has assumed access via three shafts to the underground facilities with one shaft dedicated to the transfer of used fuel containers to the underground repository. A possible alternative access arrangement would be to replace one shaft with a ramp where the ramp would be used primarily for the transfer of used fuel containers.The access concepts for proposed repositories for spent (used) nuclear fuel and other high level wastes in Finland, Sweden and Germany have been reviewed. The majority of the repository designs in these countries include a ramp as a primary means of access into the underground repository largely due to limited local shaft sinking experience. All repository designs with a ramp access also include shafts for personnel movement, transport of light-weight materials and ventilation.A trade-off study was performed to compare shaft access with a ramp access option for the APM deep geological repository and to determine whether or not ramp access should be introduced into the APM deep geological repository design. This comparative evaluation took into consideration a variety of factors related to construction, site characterization needs, operations, maintenance, operational safety, long-term safety, cost and schedule. Although ramp access has some advantages over shaft access, it was determined that these advantages were not considered sufficient to change to ramp access as the primary route for transfer of used fuel containers into the underground repository.