1
25-071
Practical Model Approach for Relationship Between Radioactive
Waste Container Emplacement Position and the Spatial Thermal
Radiation in Dry Salt Grit Backfill
Louis Schaarschmidt
TU Bergakademie Freiberg, Germany
Ibrahim Alsalamin
TU Bergakademie Freiberg, Germany
Helmut Mischo
TU Bergakademie Freiberg, Germany
ABSTRACT
In order to store high-level radioactive waste underground,
the German repository concept considers clay, crystal-
line and salt formations as suitable host rock materials
(National Citizens’ Oversight Committee, 2024). The cur-
rent research projects of the Chair Underground Mining
Methods at TUBAF (Technical University Bergakademie
Freiberg) in nuclear waste repositories mainly focus on stor-
age within salt formations.
In this scenario, the high-level radioactive waste is sup-
posed to be packed into specifically designed containers and
then transported underground and emplaced in horizontal
storage drifts. The residual temperature of the radioactive
waste leads to the question if there are optimization pos-
sibilities for waste handling, the storage and the long-term
emplacement of such high temperature level waste.
A deeper understanding of the heat transmission from
the container into the host rock might lead both towards
possibly shorter surface interim storage times as well as size
optimization possibilities of the repository itself. TUBAF
has conducted research that successfully proved that an
optimized container positioning yields more favorable ther-
mal patterns and can be achieved with conventional mining
equipment.
INTRODUCTION
Disposing high-level radioactive waste is a challenge that
every country with nuclear power plants will eventu-
ally face at some point. Developing respective repository
concepts is a task that occupies academic institutions and
scientists since decades. Due to each country’s naturally
given individual geological constraints, there is no one-fits-
all approach available. The European Commission, e. g.,
decided that each European country has to develop its own
radioactive disposal concept and individual site.
Depending on the available rock types, a multi-level-
decision process is initiated in order to determine an opti-
mal location for the underground and surface infrastructure.
Germany currently identified three possible types of host
rock: Rock salt, crystalline rock and clay stone formations
(National Citizens’ Oversight Committee, 2024). Within
the German rock salt concept, so called POLLUX contain-
ers are supposed to host the HLW (high-level waste), which
then are transported underground and placed into disposal
drifts.
Subsequently, salt grit will be applied to backfill the
drifts and act as a technical barrier between the heat-emit-
ting POLLUX containers and surrounding rock.
Currently, no detailed emplacement concept has been
officially proposed for POLLUX containers. The research
team at the Chair of Underground Mining at Technische
Universität Bergakademie Freiberg identified this research
gap and carried out several in-situ and laboratory experi-
ments within the scope of a Master’s Thesis and on-going
PhD research to investigate POLLUX emplacement and
how it affects the surrounding underground infrastructure
as well as thermal radiation patterns.
The proposed hypothesis was that lowering the
heat-emitting POLLUX into the disposal drifts floor by
entrenching would lead to an increased contact surface,
ultimately transferring more heat into the ground, which
has a higher thermal conductivity than the backfill.
25-071
Practical Model Approach for Relationship Between Radioactive
Waste Container Emplacement Position and the Spatial Thermal
Radiation in Dry Salt Grit Backfill
Louis Schaarschmidt
TU Bergakademie Freiberg, Germany
Ibrahim Alsalamin
TU Bergakademie Freiberg, Germany
Helmut Mischo
TU Bergakademie Freiberg, Germany
ABSTRACT
In order to store high-level radioactive waste underground,
the German repository concept considers clay, crystal-
line and salt formations as suitable host rock materials
(National Citizens’ Oversight Committee, 2024). The cur-
rent research projects of the Chair Underground Mining
Methods at TUBAF (Technical University Bergakademie
Freiberg) in nuclear waste repositories mainly focus on stor-
age within salt formations.
In this scenario, the high-level radioactive waste is sup-
posed to be packed into specifically designed containers and
then transported underground and emplaced in horizontal
storage drifts. The residual temperature of the radioactive
waste leads to the question if there are optimization pos-
sibilities for waste handling, the storage and the long-term
emplacement of such high temperature level waste.
A deeper understanding of the heat transmission from
the container into the host rock might lead both towards
possibly shorter surface interim storage times as well as size
optimization possibilities of the repository itself. TUBAF
has conducted research that successfully proved that an
optimized container positioning yields more favorable ther-
mal patterns and can be achieved with conventional mining
equipment.
INTRODUCTION
Disposing high-level radioactive waste is a challenge that
every country with nuclear power plants will eventu-
ally face at some point. Developing respective repository
concepts is a task that occupies academic institutions and
scientists since decades. Due to each country’s naturally
given individual geological constraints, there is no one-fits-
all approach available. The European Commission, e. g.,
decided that each European country has to develop its own
radioactive disposal concept and individual site.
Depending on the available rock types, a multi-level-
decision process is initiated in order to determine an opti-
mal location for the underground and surface infrastructure.
Germany currently identified three possible types of host
rock: Rock salt, crystalline rock and clay stone formations
(National Citizens’ Oversight Committee, 2024). Within
the German rock salt concept, so called POLLUX contain-
ers are supposed to host the HLW (high-level waste), which
then are transported underground and placed into disposal
drifts.
Subsequently, salt grit will be applied to backfill the
drifts and act as a technical barrier between the heat-emit-
ting POLLUX containers and surrounding rock.
Currently, no detailed emplacement concept has been
officially proposed for POLLUX containers. The research
team at the Chair of Underground Mining at Technische
Universität Bergakademie Freiberg identified this research
gap and carried out several in-situ and laboratory experi-
ments within the scope of a Master’s Thesis and on-going
PhD research to investigate POLLUX emplacement and
how it affects the surrounding underground infrastructure
as well as thermal radiation patterns.
The proposed hypothesis was that lowering the
heat-emitting POLLUX into the disposal drifts floor by
entrenching would lead to an increased contact surface,
ultimately transferring more heat into the ground, which
has a higher thermal conductivity than the backfill.