Final report of the STROEFUN Phase III research project (detailed knowledge of contact area & injection materials, in situ tests)

• 20230612_STROEFUN_III_Abschlussbericht_01.pdf
  
• 20231205_STROEFUN_III_Schlussbericht_Technischer_Anhang.pdf
  

Language: German

Bei der Planung eines Endlagers für wärmeentwickelnde radioaktive Abfälle und ausgediente Brennelemente (kurz: HAW-Endlager) in Tongesteinsformationen ist der technische Ausbau von Grubenbauen von wesentlicher Bedeutung für den sicheren Betrieb des Endlagers. Aus gebirgsmechanischer Sicht ist die Errichtung und der sichere Betrieb eines HAW-Endlagers im Tongestein ohne einen geeigneten Ausbau nicht möglich. Die Tongesteinseigenschaften (z. B.: geringe bis mäßige Festigkeit, Kriechverhalten, Eigenschaftsänderungen in Abhängigkeit des Wassergehaltes) in Verbindung mit der jeweiligen Teufenlage führen zu hohen Anforderungen an die Tragfähigkeit des verwendeten Ausbausystems. Die Projektpartner DMT GmbH &Co. KG und BGE TECHNOLOGY GmbH setzten sich zum Ziel, im Vorhaben AGEnT die Anforderungen zur Auslegung von stützenden Ausbauten im Grubengebäude eines Endlagers in Tongestein zusammenzustellen, grundlegende technische Lösungen zu entwickeln und mögliche Wechselwirkungen der dafür in Betracht kommenden Baustoffe mit den anderen Komponenten des Endlagersystems, wie dem Wirtsgestein inkl. Porenwasser, zu untersuchen.

In the R&D project BASEL (FKZ 02E 11486 B), a method to evaluate the interactions between the safe construction and operation of a repository for high-level radioactive waste and long-term safety was developed. A corresponding requirement is defined in the German safety requirements (EndlSiAnfV). The methodology is based on a catalogue of generic features, events, and processes (FEPs) for the operating phase of repository mines in different host rocks. Based on this, impacts from inside that affect repository operations were identified and suitable measures to avoid or mitigate their consequences were derived. Furthermore, the effects of impacts from inside and of the measures derived on long-term safety were evaluated.

The R&D project BASEL was a joint project of BGE TECHNOLOGY GmbH and Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH. It started in April 2016 and ended in September 2020.

The KOMPASS research project (FKZ 02E 11708) was a consequence of the requirement of safe containment of radioactive waste within a containment providing rock zone. Crushed salt, when fully compacted, is capable of restoring the natural rock salt barrier. This capability was not considered systematically earlier because safety assessments focused on limiting the release of radionuclides instead of on their isolation. Thus, regarding crushed salt behaviour, a knowledge gap in the area of low salt porosity close to the fully compacted state was identified. The objective of the KOMPASS project was the development of methods and strategies to reduce deficits in the prediction of crushed salt compaction in order to improve the prognosis quality. This included the development of experimental methods for determining crushed salt properties in the range of low porosities, the improvement of process understanding, and the investigation and further development of existing numerical models.

The R&D project KOMPASS was funded by the Federal Ministry for Economic Affairs and Energy and carried out jointly by BGE TECHNOLOGY GmbH, Bundesanstalt für Geowissenschaften und Rohstoffe, Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH, Institut für Gebirgsmechanik GmbH, and Technische Universität Clausthal from September 2018 to August 2020. Sandia National Laboratories, USA, contributed to the project as an associated partner.

In the KoBrA research project (FKZ 02E 11527), requirements for waste containers for high-level radioactive waste were derived systematically for the very first time, taking into account the international state of the art in science and technology. For this purpose, the boundary conditions and stress parameters relevant for repositories in the three potential host rocks – rock salt, claystone, and crystalline rock – were determined. Based on this, the container functions necessary to meet the requirements under the given impacts and stresses were determined, and initial and conceptual ideas for future waste containers were discussed and developed. Conclusions and recommendations for the next steps on the way to the development of waste container concepts that meet the requirements for the final disposal of high-level radioactive waste complete the project results. The results, including the derivation of a methodological approach, are described in detail in the final report and in independent reports on four work packages.

The R&D project KoBrA was carried out jointly by BGE TECHNOLOGY GmbH and the Federal Institute for Materials Research and Testing (BAM) from July 2017 to October 2020.

On the basis of detailed qualitative observations and numerical analyses carried out in the RESUS project for ten repository systems in the host rocks crystalline rock, rock salt and argillaceous rock, recommendations are derived on how to aggregate the individual results into the eleven geoscientific consideration criteria. The individual evaluations of the consideration criteria result in each case from a different number of evaluation-relevant characteristics and evaluation variables or indicators. For each criterion, an individual evaluation is first performed, for which specific aggregation steps are described.

The recommendations are based on qualitative considerations of the importance of the evaluation-relevant properties of the consideration criteria for the long-term safety of repository systems, where the confinement of radionuclides must essentially be ensured either by the geological barrier or by engineered and geotechnical barriers. The containment effectiveness of these essential barriers (integrity) is of crucial for the permanent, post-closure containment of radionuclides. Therefore, results of quantitative analyses on the integrity of the geological barrier as well as on the confinement of the radionuclides were considered in the derivation of the recommendations. The results of the project were presented at several technical conferences. Drafts of the results reports were posted online in April 2020 with the opportunity for comments to be submitted at GRS website. Feedback from these forums was taken into account in the preparation of the final report versions.

By applying the methodology proposed here for aggregating the assessments to the geoscientific consideration criteria, an important basis for decision-making can be obtained for the verbal-argumentative assessment on the overall geological situation in a subarea, a siting region or a site.

In the final report of the MONTANARA project, you will first find an overview on monitoring in an international context as well as the framework conditions for monitoring in Germany. Thereafter, proposals are presented on how a monitoring concept can be developed in connection with a safety case for a HAW repository. These suggestions are supplemented by examples of monitoring concepts especially with regard to geotechnical barriers. Furthermore, a discussion on the use of monitoring results in the context of decision-making processes and confidence building will be given with regard to the possibilities but also the limitations of monitoring.

The project was carried out in close cooperation with the European joint project on monitoring "MODERN2020", which focused on monitoring strategies, monitoring technologies and the potential involvement of external stakeholders.

Das Ziel des Projektes war es, die technische Umsetzung von Rückholungskonzepten weiter zu konkretisieren, sicherheitstechnische Konsequenzen und Auswirkungen der Sicherheitsanforderung „Rückholbarkeit“ auf die Endlagerauslegung weiter vertieft zu untersuchen und die Auswirkungen hinsichtlich Aufwand und Zeitbedarf aufzuzeigen. Die Planungen sollen Grundlagen für eine genehmigungsreife technische Lösung liefern.

In Deutschland ist die Möglichkeit zur Rückholung als Auslegungsanforderung an ein Endlager für wärmeentwickelnde radioaktive Abfälle und ausgediente Brennelemente seit dem Jahr 2010 in den Sicherheitsanforderungen des BMU festgelegt. Die Erfüllung der Sicherheitsanforderungen ist Genehmigungsvoraussetzung für die Inbetriebnahme des Endlagers. Innerhalb des wurden zunächst allgemeine Fragestellungen zur Umsetzung und Implementierung der Rückholungsforderung für ein Endlager für wärmeentwickelnde radioaktive Abfälle und ausgediente Brennelemente beantwortet. Im Anschluss erfolgte eine Weiterentwicklung und vertiefende Planung für eine mögliche Rückholung von Endlagerbehältern für das Konzept der Strecken- und Bohrlochlagerung im Salz- und Tongestein. Darüber hinaus wurden Arbeitsprogramme zur Realisierung des Nachweises der technischen Machbarkeit für die relevanten Komponenten der Rückholungskonzepte erarbeitet.

Im Rahmen des FuE-Vorhabens ERNESTA wurden bestehende Rückholungskonzepte weiterentwickelt und diese in vier Teilberichten ausführlich beschrieben:

• Technische Konzepte für die Rückholung der Einlagerungsvariante vertikale Bohrlochlagerung
  - in Salzformationen und
  - in Tongesteinsformationen
   
• Technische Konzepte für die Rückholung der Einlagerungsvariante horizontale Streckenlagerung
  - in Salzformationen und
  - in Tongesteinsformationen

• ERNESTA-Projekt-FINAL_Bohrloch_Salz.pdf
  
• ERNESTA-Projekt-FINAL_Bohrloch_Ton.pdf
  
• ERNESTA-Projekt-FINAL_Strecke_Salz_klein.pdf
  
• ERNESTA-Projekt-FINAL_Strecke_Ton.pdf
  

For many decades, the development of repository concepts and safety analyses for a repository in a salt dome was prioritized in Germany while repository concepts for claystone and crystalline rock have been taken into account for the past two decades only. So far, bedded salt formations have not been the subject of comparative investigations. Thus, in summer 2015, the Federal Ministry for Economic Affairs and Energy (BMWi) launched the R&D project KOSINA to develop repository designs and carry out safety analyses for different disposal options in a generic bedded salt formation and a generic salt pillow. KOSINA is a German acronym for "Concept development for a generic repository for heat-generating waste in bedded salt formations in Germany as well as development and testing of a safety and demonstration concept". Together with its partners BGR, GRS, and IfG, BGE TECHNOLOGY GmbH has carried out an almost three years lasting scientific programme. The core areas of the programme are the development of generic geological models, including derivation of model parameters, the development of a safety and demonstration concept, the development of technical repository designs for four different disposal options, the analysis of geomechanical integrity, the evaluation of operational safety as well as the analysis of radiological consequences. An interim report, which compiles the basic data of the waste inventory, the repository design requirements, the data basis for geological model developments, and the outline of a safety and demonstration concept, was already published in February 2016. The main achievements of R&D project KOSINA are the development of four different disposal options, two per each generic geological model (flat-bedded salt, salt pillow) based on thermo-mechanical calculations. This includes the implementation of a safety concept that provides containment of the radioactive materials with regard to the technical designs of waste packages, transport and emplacement technologies, as well as backfilling and sealing concepts. Furthermore, the integrity of the geological barriers could be demonstrated for all four disposal options, and the long-term predictions showed no radiological releases during the demonstration period of one million years.