The Enhanced Sealing Project: monitoring of a full-scale in situ composite shaft seal from 2009 to 2013, and related hydro-mechanical numerical modelling

Two full-scale seals were installed in the access shaft and vent raise at Atomic Energy of Canada's (AECL's) Underground Research Laboratory (URL) (Figure 1) as part of URL closure activities. The seals were installed where the main shaft and vent raise intersect a water-bearing fracture zone (FZ2), approximately 273 m below the ground surface. The primary purpose of these seals is to limit the mixing of saline groundwater from the deeper regime, with the fresher, nearer-surface groundwater. In this respect, it is intended to function in the same manner as a shaft seal in a repository containing radioactive waste, although there is no radioactive waste stored at the AECL's URL. Construction of these two seals was completed as part of Canada's Nuclear Legacy Liabilities Program (NLLP). A jointly-funded monitoring project, called the Enhanced Sealing Project (ESP) was developed by AECL (Canada) and was supported by the NWMO (Canada), SKB (Sweden), Posiva (Finland), and ANDRA (France) from 2009 to 2013. The purpose of the ESP is to monitor the thermal-hydraulic-mechanical (THM) evolution of the seal installed in the main shaft and the rock immediately adjacent to it. The other seal in the ventilation raise was not monitored and not part of the ESP. (author)