A Methodical Approach to Deep Borehole Sealing System Planning

Deep borehole #disposal enables the disposal of #radioactivewaste in deep rock formations that have properties favorable for long-term isolation. Boreholes are preferred pathways for fluids, which could mobilize radionuclides in the disposal zone, and for contaminated fluids. For this reason, seals that separate the disposal zone from the areas near the earth‘s surface play an important role.

The Finnish Mitta Oy Group together with sub-consultants AINS Group of Finland, VTT Technical Research Centre of Finland, and of Germany are currently working with Norsk nukle?r dekommisjonering (NND) on the concept development and technical design for NND’s disposal solutions for radioactive waste in #Norway. One concept is the #implementation of the National Facility as a combination of different types of #disposal facilities. A deep borehole disposal (DBD) facility for SNF and/or HLW could be part of such a solution.

BGE TEC developed a methodical approach for planning sealing systems that are to restore the integrity of the host rock. This approach is based on the experience that BGE TECHNOLOGY GmbH has gained in the course of the planning and construction of seals in mine shafts, underground drifts, and exploration boreholes. Its main aspects are the

• Identification of necessary preparation work inside the borehole, e.g. removal of casings and cementations, or the injection of damaged rock zones
• Selection of sealing elements with different functionality that provide redundancy of the overall sealing function
• Selection of sealing materials adapted to thermal, hydraulic, chemical, and mechanical conditions to be expected in the borehole
• Definition of locations and lengths of individual sealing elements, taking into account static and dynamic loads as well as hydrogeological conditions, and, especially the locations of tectonic faults

The work is part of several tasks carried out by BGE TEC that are related to the development of a DBD concept for NND and you can read more about it here: