Concretisation of host-rock-dependent canister concepts through the development of a consistent but variable multi-barrier system for the future engineered barrier system

Abstract. A clear and necessary shift in the site selection process is emerging, as
otherwise a participatory, science-based, transparent, self-questioning,
learning and reversible process seems futile. The questions of guaranteeing
safety and the careful trade-offs to be made with extensive participation of society therefore require a rethink with regard to the time set for site
selection (StandAG – targeted site selection 2031). Since this also pushes
the decision on the selection of a host rock even further into the future,
the question arises as to how the preparation of technical developments can
be continued in a manner as concrete as possible. In particular, answering
questions about the type of technical barrier, i.e. the development of
the barrier system, therefore runs the risk of not being able to be advanced with the necessary focus (“pressure on the vessel”). In this paper, a methodical approach is presented on how the container development can be advanced in a target-oriented manner through research and development, even without a quick decision for a host rock. The basis of the approach is the division of the consideration of the engineered barrier system (EBS) development into two approaches. The first approach is from the “inside to the outside” of the inventory, so that the questions of radiological safety, heat flow and nuclide release are focused and can essentially be regarded as independent of the host rock. The second approach then focuses on the environmental influences on the container, the “outside to inside”. With this, the individual systems can be worked out depending on the host rock, which can then be coupled modularly with the first approach. It is not necessary to know the exact coupling point or the number of possible barriers in such a system. Through an intelligent choice of the coupling point later on as well as the number of barriers, the previous requirements for the repository containers for highly radioactive materials can thus be regarded, and the necessary flexibility for the requirements that still need to be further specified is maintained nevertheless. The findings on this are based on the work in the completed collaborative project ENTRIA (Entsorgungsoptionen für radioaktive Reststoffe: Interdisziplinäre Analysen und Entwicklung von Bewertungsgrundlagen), the ongoing collaborative project TRANSENS (Transdisziplinäre Forschung zur Entsorgung hochradioaktiver
Abfälle in Deutschland) and the associated interdisciplinary and transdisciplinary exchange in many scientific and societal discussions, as well as the disciplinary research project ElaBeMa (Recherche und Beschreibung für das Endlagerbehältersystem in Frage kommende Materialien), which is currently ongoing.


The site selection process in Germany failed because the design of the process and the safety of the process cannot be reconciled.As part of an amendment, Thomauske suggests carrying out a cross-host rock comparison before evaluating sub-areas.
Too tight a time limit as well as long extensions in the process pose the risk of non-safety-oriented decisionmaking behavior.There is little potential for acceleration until a procedural change is made, but the change in the law must begin quickly.

First Aproach
General view from the inside Consequence approach 1 • Container development will only take place after the location and thus the host rock have been decided ➔ Danger of delay?
• From now on, three equivalent complete container systems will be designed, planned, constructed and implemented in parallel ➔ Costs and resources?
• Defined requirements for the container must be defined, although one cannot know whether these actually exist at the future location ➔ Depth, water, etc.?
• A change of direction in a late phase of site selection is no longer easily possible when the host rock changes ➔ see change of direction in Switzerland!
• Production capacities can only be built up after the location decision has been made ➔ Pre-programmed bottleneck for 10.000 to 20.000 containers? •

Methodical approach of design thinking:
Basic idea: Design thinking is about designing innovations and creative solutions to complex problems.

Possibilities:
There are no limits to the range of applications of design thinking.It can be applied to products and services as well as to the development of concepts for entrepreneurial or social issues.

Functional scope:
Design thinking is as much a collection of methods as it is a way of thinking and can be defined differently depending on the application.Techniques and tools enable a systematic approach.

Acceptability:
Openness to results, allowing for mistakes, the courage to fail and the willingness to learn from failure form the necessary inner attitude and fit exactly into the StandAG's objectives.

What next? ➔ Think new approaches!
The classic design thinking process is divided into two main phases:

Analysis und Synthesis.
The two main phases can be divided into six further sections: What to consider?
This approach is not fully optimized to a host rock, so all design criteria must be based on conservative boundary conditions: • allowable heat generation as a general boundary condition • permissible dose rate at the surface of the vessel • permissible mechanical load worst case oriented • self-shielding or overpack?
• Line storage or vertical in boreholes?
• ... The procedure must be designed as a transparent learning process to bring society along and achieve acceptability.However, the number of containers to be stored can thus be determined at a very early stage so that, for example, production capacities can be created in the market.
be taken to counteract a further delay in the final disposal of highly radioactive waste?Are there tasks that can be decoupled from the host rock issue and can therefore be addressed before this decision is made?Source: BGE GmbH Workshop des Planungsteams Forum Endlagerplanung; Vorstellung des Rahmenterminplans bis zum Vorschlag für Standortregionen Online-Veranstaltung, 13.01.2023,Translation added by the author!Appointment to the final storage container Interim storage: Licenced for 40 years as of first packaging / storage of cask, e

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Number of containers can be optimally designed ➔ Storage space required!© Leibniz Universität Hannover, IW, Prof. Dr.-Ing.Hans Jürgen Maier, Dr.-Ing.Thomas Hassel Page 8 The highly radioactive inventory is known ➔ Burnup and heat generation!• The quantity of the waste is known ➔ Design requires definition of criteria!• Shape and dimensions as construction data are available ➔ BE, special fuels and vitrified molds!• Radiological requirements are already defined ➔ Dose rate on the surface!• Material decisions can be made using the international state of the art ➔ SKB/ POSIVA/ NAGRA! • Partial approval procedures can start early ➔ Process flow!• Production capacities available quickly ➔ No production bottlenecks!• Larger number of containers for target host rock ➔ Safety surcharges! • The long-term stability part can be handeld after the decision has been made ➔ time, costs!What next?➔ Thinking new approaches!
tubes made of unalloyed steel to accommodate the fuel elements 2. Casting of these tubes with cast iron (GGG40) 3. Inner steel cover screwed 4. Enclosing of the inlet with a copper cladding 5. Seal welding of Cu cladding and Cu cover Source: Raiko, H., Sandström, R., Ryden, H., and Johansson, M. 2010.Design analysis report for the canister.Technical Report TR-10-28.Swedish Nuclear Fuel and Waste Management Co. Example: Sweden (SKB)/Finland (POSIVA) Finland -only licensed repository in the world -crystalline rock