Impact of Climate Change on Far-Field and Biosphere Processes for a HLW
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Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH Impact of climate change on far-fi eld and biosphere processes for a HLW-repository in rock salt GRS - 241 Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) mbH Impact of climate change on far-fi eld and bisophere processes for a HLW-repository in rock salt Ulrich Noseck Christine Fahrenholz Eckhard Fein Judith Flügge Gerhard Pröhl Anke Schneider März 2009 Remark: This report, with the German title „Wissenschaftliche Grundlagen zum Nachweis der Langzeitsicherheit von Endlagern (Kurztitel WiGru5)“, was prepared under the contract No. 02 E 9954 with the Federal Ministry of Economics and Technology (BMWi). The work was conducted by the Ge- sellschaft für Anlagen- und Reaktor- sicherheit (GRS) mbH. The authors are responsible for the content of this report. GRS - 241 ISBN 978-3-939355-15-1 Keywords: biosphere, climate, climate change, glacial, hydrogeology, interglacial, permafrost, radioactive waste, safety assessment, transport Preface The assessment of the long-term safety of a repository for radioactive or hazardous waste requires a comprehensive system understanding and capable and qualified numerical tools. All relevant processes which contribute to mobilisation and release of contaminants from the repository, transport through the host rock and adjacent rock formations as well as exposition in the biosphere have to be implemented in the programme package. The objective of the project “Scientific basis for the assessment of the long-term safety of repositories”, identification number 02 E 9954, was to follow national and international developments in this area, to evaluate research projects, which contribute to knowledge, model approaches and data, and to perform specific investigations to improve the methodologies of the long-term safety assessment. This project, founded by the German Federal Ministry of Economics and Technology (BMWi), was performed in the period from 1st November 2004 to 31st July 2008. The results of the key topics investigated within the project are published in the following reports: GRS-report 222: About the role of vapour transport during bentonite re-saturation GRS-report 238: Elemente eines Safety Case zur Realisierung eines Endlagers in Deutschland GRS-report 239: Chemical effects in the near field of a HLW repository in rock salt GRS-report 240: Safety and Performance indicators for repositories in clay and salt formations GRS-report 241: Impact of climate change on far-field and biosphere processes for HLW repositories in rock salt GRS-report 242: Gase in Endlagern im Salz The results of the whole project are summarised in the overall final report: GRS-report 237: Assessment of the long-term safety of repositories. Scientific basis I Acknowledgment We thank Antje Schwalb, Klaus-Dieter Meyer and Andrey Ganopolski for fruitful discussions and helpful comments. II Contents Preface ...................................................................................................... I Acknowledgement ................................................................................... II 1 Introduction .............................................................................................. 1 2 The climate ............................................................................................... 3 2.1 Definition and classification ........................................................................ 3 2.2 Influence of the climate on the biosphere ................................................... 5 2.3 Climate archives: witnesses of ancient climates......................................... 7 2.4 Factors influencing climate ........................................................................ 9 2.4.1 Primary factors ........................................................................................ 10 2.4.2 Secondary factors .................................................................................... 14 2.5 The quaternary climate history of Northern Germany ............................... 21 2.5.2 Holsteinian interglacial ............................................................................. 27 2.5.3 Saalian glacial ......................................................................................... 29 2.5.4 Eemian interglacial .................................................................................. 29 2.5.5 Weichselian glacial .................................................................................. 31 2.5.6 Holocene ................................................................................................. 39 2.5.7 Conclusions ............................................................................................. 44 3 Climate Models ...................................................................................... 47 4 Potential future climate changes .......................................................... 51 4.1 Conclusions from past climate cycles ...................................................... 51 4.2 Results from model calculations .............................................................. 52 4.2.1 Global climate changes............................................................................ 52 4.2.2 Regional climate changes in Northern Germany ...................................... 55 4.3 Conclusions on future climate development ............................................. 61 5 The reference site Gorleben.................................................................. 65 5.1 Geographical position .............................................................................. 65 III 5.2 Geology ................................................................................................... 67 5.2.1 Zechstein to Cretaceous .......................................................................... 68 5.2.2 The Tertiary ............................................................................................. 69 5.3 Hydrogeology and hydrochemistry ........................................................... 70 5.4 Actual climatic conditions ......................................................................... 73 6 Modelling of selected climate states .................................................... 77 6.1 Warming climates .................................................................................... 78 6.2 Colder climates ........................................................................................ 82 7 Modelling climate impact on flow and transport processes ............... 87 7.1 Present Climate ....................................................................................... 88 7.1.1 Geometry ................................................................................................. 88 7.1.2 Hydrogeological parameters .................................................................... 90 7.1.3 Initial and boundary conditions ................................................................. 90 7.1.4 Results of flow modelling for the Present Climate .................................... 92 7.2 Selection of relevant climate states .......................................................... 96 7.3 Constant Climate ..................................................................................... 96 7.3.1 Derivation of the flow model ..................................................................... 97 7.3.2 Results .................................................................................................... 97 7.4 Sea Water Inundation .............................................................................. 98 7.4.1 Derivation of the flow model ..................................................................... 99 7.4.2 Results .................................................................................................. 100 7.5 Permafrost ............................................................................................. 103 7.5.1 Derivation of the flow model ................................................................... 104 7.5.2 Results .................................................................................................. 105 7.5.3 Subrosion rate ....................................................................................... 108 7.6 Summary and conclusions ..................................................................... 111 7.7 Transport model..................................................................................... 113 7.7.1 Derivation of the transport model ........................................................... 113 7.7.2 Results .................................................................................................. 118 7.8 Summary and conclusions ..................................................................... 156 IV 8 Modelling of climate impact on biosphere processes ...................... 169 8.1 Introduction ............................................................................................ 169 8.2 Methodology .......................................................................................... 169 8.2.1 Site characteristics ................................................................................. 169 8.2.2 Climate analogue stations ...................................................................... 170 8.2.3 Radionuclides ........................................................................................ 173 8.2.4 Geosphere-biosphere interfaces and climate states