atw 2018-05v6

inforum

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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