The International Atomic Energy Agency (IAEA) is launching a new Coordinated Research Project (CRP) to increase international knowledge and drive progress towards testing deep borehole disposal (DBD) for intermediate and high-level radioactive waste.

The internationally established approach is for disposal of used fuel is in a mined deep geological repository (DGR) in the Earth’s bedrock. Finland is set to implement the world’s first DGR, and several other countries are advancing their DGR programmes.

The new CRP has been launched in response to interest expressed by several countries – for example Australia, Croatia, Denmark, Norway and Slovenia – in further exploring whether DBD might also provide a suitable option for disposal of their specific inventory of radioactive waste. The primary motivation is to develop a more cost-effective disposal approach, without jeopardising safety. Further studies on the DBD concept can build on decades of prior desktop studies conducted in countries such as the UK and the USA, as well as on some recently conducted scoping studies.

“Several countries want to find out if deep borehole disposal would be suitable for their specific waste inventories,” said Stefan Mayer, an expert in radioactive waste disposal at the IAEA. “The conceptual studies and generic assessments done so far look promising, and to take the idea further, the IAEA is inviting research organisations to join this four-year CRP, which aims to help countries make an informed decision on whether to choose DBD.”

The DBD concept considers disposal in a stable geologic formation at depths of several kilometres into the base rock, although recent scoping studies have also considered depths of several hundred metres – comparable to those of a mined DGR. The photograph above illustrates vertical emplacement and stacking of waste disposal containers over the height of a disposal zone, assumed to be located deep within the bedrock. The borehole above the disposal zone would be plugged and sealed over a height of several kilometres. Alternative depths and heights of the disposal zone are also being considered, and the specific design depends on the volume and specific properties of radioactive waste, as well as on the specific properties of the site selected for borehole disposal.

The overall objective is to provide a comprehensive suite of assessments at the strategic and programmatic level to help countries make an informed decision on DBD. The intention is to expand the scientific and technical groundwork demonstrating the safety and implementation of the DBD concept to effectively provide the basis for a future field-scale demonstrator. The CRP also hopes to develop preliminary plans for a field demonstrator of the deep borehole concept that aligns with the national needs of at least one of the CRP participants.

Specific research objectives include:

  • Structuring the deep borehole disposal concept, the associated materials, concept of operations as well as construction and closure, and also assessing and progressing, as needed, the corresponding technical readiness levels;
  • Identifying site data needs, assessing and progressing, as needed, the capacity to conduct site characterisation for DBD;
  • Assessing and progressing as needed monitoring approaches allowing to verify the as-built conditions;
  • Considerations of safeguards by design;
  • Assessing and progressing as needed the suite of functions and performances the DBD system is expected to deliver, as well as the associated scenarios, FEPs (features, events and processes), models and simulation capacity;
  • Operational risk assessment and long-term safety assessment.

Proposal for Research Contract or Agreement must be submitted by 15 October 2023.

Image: A schematic illustration of a deep borehole repository assuming disposal into a bedrock (courtesy of IAEA)