Construction methods for underground RW disposal facilities: analysis of international experience

Deep geological repositories for radioactive waste (DGR) and underground research laboratories (URL) preceding them are being developed and constructed in most countries with developed nuclear power sector. International practices show that DGR and URL designs involve various types of excavations widely used to provide access to the target depths: vertical and inclined shafts, their combinations, as well as spiral ramps. In world practice, inclined workings, which include inclined shafts and spiral ramps, became widely used in the second half of the XX century at mining enterprises along with the development of mechanized mining methods for various types of rocks. The inclined workings can be 6—8 times longer compared to vertical shafts, which inherently increases the cost of their excavation. However, in certain cases, a longer inclined working and transportation along it by road transport provides such considerable advantages that its construction turns out to be a much more feasible option compared to vertical shaft designs with a cage hoist. The decision to excavate a spiral ramp or an inclined shaft can be made both at the DGR construction and operational stage. In the decision-making, a fairly wide range of factors is commonly taken into account, including economic efficiency, mining and geological conditions and the need to enhance the safety of individual production processes. In particular, with regard to radioactive waste disposal facilities, an inclined working facilitates the system of package delivery to the disposal depths reducing the risks and possible consequences of emergency situations and incidents associated with equipment failures. At the URL stage, an inclined working facilitates and provides more detailed rock mass characterization.