atw Vol. 63 (2018) | Issue 5 ı May
| | Fig. 2.
Parts of disposal planning, which can be replaced by a calculation tool.
waste properties by conditioning
processes and the possible combinations
of packaging variants resulting
therefrom are currently calculated
manually. This complex process can
be carried out by a calculation tool.
With the data obtained at the removal
planning, the calculation tool can
carry out the planning and optimisation
of conditioning and packaging
and supports a repository documentation.
Therefore the calculation tool
supports the planning, optimisation
and calculation of packaging according
to the final storage conditions and
prepares and simplify the repository
documentation. This workflow is
shown in Figure 2.
2 Characteristics of
packaging planning
During the post-operational phase of
a nuclear installation, dismantling can
be planned. This implies the planning
of the dismantling as well as the planning
of conditioning and packaging of
the radioactive waste with a final
disposal documentation. When disassembling,
statements about the
properties of the waste can be made.
The required conditioning processes
are dependent of the material properties.
These properties such as volume,
mass, state of matter and flammability
will be changed by conditioning processes.
For example, by high-pressure
compression, the volume of raw waste
can be reduced by up to 80 %, using
incineration a reduction by 98 %
can be achieved and by a combination
of high-pressure compression and
incineration, the waste can be reduced
by up to 99 % [2]. By reducing the
volume, the radioactivity is concentrated.
Depending on raw waste and
conditioning process, different volumes
of radioactive waste with
different properties result. This is
crucial for packaging planning. The
needed parameters for final storage of
the waste results of material analyses
and calculations. For all conditioning
processes a qualification is necessary.
Therefore evidences for the realization
of the conditioning according to
the given restrictions and corresponding
conditioning systems at the site
are needed.
Moreover, there are various types
of containers available in various
categories for the final disposal packaging
of radioactive waste. Furthermore,
restrictions in terms of mass,
volume, radiology and other waste
properties are given in the final
disposal conditions [3]. These restrictions
must be checked for each
container. The evidence for the permissibility
of the used containers is
also required. This could be implemented
by manufacture certificates
and handling instructions.
Further influencing factors for
choosing the type of container can be
given by local boundary conditions of
the site. Equipment for handling of only
a specific type of container without the
possibility to adapt the transport system
to another type of container can be
such an example. The available storage
area inside of a site can be a logistic
challenge which has to be accounted.
Compliance to the transport regulations
has to be given at every time
inside the site and during transport.
These restriction parameters for
packaging which are necessary to be
taken into account by a calculation
tool for holistic waste management
planning are shown in Figure 3.
3 Development of the
calculation tool
The calculation tool has a modular
structure. In individual modules, the
conditioning methods are determined,
the change in waste properties
such as volume and mass is calculated,
the locally available conditioning
procedures are determined and
compared with the required procedures,
loading time and equivalent
dose are estimated and the compliance
of the disposal conditions
regarding volume, mass and radiology
is checked. The modules are illustrated
in Figure 4.
From the calculation results of
the individual modules, the optimal
loading variant is determined and
entered into the waste data sheet in
accordance with the selected optimisation
parameter like repository
volume, loading time, container costs,
volume utilization of the last container
or radiological utilization. This
is realised by the main module, where
all information from the separate
modules are evaluated.
The user interface of the developed
calculation tool consists of an input
mask for waste-, conditioning- and
container data and an output,
where the optimal loading variant is
described.
In addition, a waste data sheet
is created, where all information determined
by the calculation tool are
inserted automatically. The individual
details, e.g. for description of the
included material or dose rate are
| | Fig. 3.
Characteristics of packaging planning which must be accounted by a calculation tool for holistic disposal planning.
DECOMMISSIONING AND WASTE MANAGEMENT 317
Decommissioning and Waste Management
Optimal Holistic Disposal Planning – Development of a Calculation Tool – ı Johannes Schubert, Anton Philipp Anthofer and Max Schreier
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