Deep geological disposal of radioactive waste in Switzerland - overview and outlook

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1 Deep geological disposal of radioactive waste in Switzerland - overview and outlook Michael Schnellmann (Section Head Geosciences) Annual Convention 2015 Baden 20 th June 2015

2 Nagra Mandate from the Swiss producers of radioactive waste to identify sites and implement radioactive waste repositories in Switzerland Financed by the waste producers NPPs, Federal Government ~100 employees including ~30 geoscientists Nagra contracts a lot of work to external specialists (consulting companies and universities) 2

producers NPPs, Federal Government ~100 employees including ~30 geoscientists Nagra

3 Radioactive Waste in Switzerland Radioactive waste has been produced in Switzerland for more than 40 years from the operation of the 5 nuclear power plants and from medicine, industry and research Waste volumes (50-year operation/collection): - High-level waste (HLW) - Low- and intermediate-level waste (L/ILW) Period of concern: <10,000 m 3 ca. 90,000 m 3 - High level waste (HLW) 1 Ma - Low and intermediate level waste (L/ILW) a 99% of radiotoxicity 1% of radiotoxicity 3

operation/collection): - High-level waste (HLW) - Low- and intermediate-level waste (L/ILW) Period of concern: <10,000 m

4 Geological repositories in Switzerland Multi barrier system HLW repository L/ILW repository Option for combined repository' 4

5 Investigations in siting regions & research at Underground Research Laboratories Mont Terri 100 km Siting regions mü. M NW Courgenay Rock Laboratory SE St-Ursanne 800 Mont Terri 600 Grimsel m 5 More details on Monday s excursion!

6 The 'Sectoral Plan' (the rules for site selection) Sectoral Plan defines: major players & their roles selection criteria 3 main stages 6

7 Site selection: 3 Stages Stage 1: Suggestion of geological siting regions looking at the full spectrum of potential host rocks in the entire county Stage 2: based mainly on existing data Reduction to at least two siting regions per repository type: comparison between siting regions; includes acquisition of new field data Siting of surface facilities for each siting region: - includes strong involvement of society in a structured manner Not discussed in this presentation Stage 3: Selection of one siting region per repository type and submission of general license application - includes intensive field work at remaining siting regions 7

data Siting of surface facilities for each siting region: - includes strong involvement of society in a structured manner Not discussed in this presentation

8 Site selection: Safety criteria 8

9 Site selection phase 1: Systematic search for siting regions 9 General Technical Summary Summary Geology

10 1. Principal suitability of large-scale areas? Spatial conditions Long-term stability HLW repository (1 million years) Alps and Folded Jura excluded (longterm stability, complexity) L/ILW repository ( years) No zone excluded as a whole 10

million years) Alps and Folded Jura excluded (longterm

11 2. Which host rocks? Northern Switzerland Low & intermediate level waste: Effinger Schichten Brauner Dogger Opalinuston & Palfris Formation (Helvetic nappes) 11

12 2. Which host rocks? Northern Switzerland High level waste: Opalinuston 12

13 3. Where are the host rocks in preferable local configurations? Opalinus Clay in preferred tectonic setting and at suitable depth ( m) Proposed siting regions accepted by the Swiss government in 2011 after an intensive review phase Exclusion of further zones (tectonic arguments) Upper Rhine Graben border zone: Dense NNE- SSW fault pattern Upper Rhine Graben border zone: dense NNE- SSW fault pattern Result: Geological Siting Regions High-level waste Low- and intermediate level waste Zones with weak indications for tectonic complexity regional fault zones 13

after an intensive review phase Exclusion of further zones (tectonic arguments) Upper Rhine Graben border zone: Dense NNE- SSW fault pattern

14 Site selection phase 2: Reduction of number of siting regions & >100 reference reports (Nagra Arbeitsberichte) 14 General Technical Summary Summary Geology

reports (Nagra Arbeitsberichte) www.nagra.

15 Geological overview Northern Switzerland Jura fold-and-thrust-belt Molasse foreland basin Autochthonus Mesozoic Permian Crystalline Basement 15

16 Reprocessed seismic data 16

17 New seismic data 17

18 Reprocessing of seismic data (Northern Switzerland ) Madritsch et al. (2013) 18

19 Reprocessing of seismic data (Wellenberg) Depth Migration (Birkhäuser et al. 1991) Depth Migration (Jung 2013) 19

20 Reprocessed vs. new data (Northern Switzerland) Madritsch et al. (2013) 20

21 Compilation and analyses of gravity data Nagra 2014, Dossier II, based on Green et al. (2013) 21

22 Mapping regional tectonic elements 22 More about tectonic situation in follwoing presentations

23 Geophysical logging in third party boreholes GTB Schlattingen-1 Transect Jura Südfuss 23

24 Geophysical logging in third party boreholes Transcect Jura Südfuss 24

25 Relevance of competent layers in host rock & confining units clay rich sequence Hard beds Fracture Network clay rich sequence Fault Region with potential for strongly enhanced water flow (hard beds with clay content <20%) Region with potential for moderately enhanced water flow (clay-richt series with clay content 20 40%) or no enhanced water flow (>40% clay content) 25

26 Long-term geological evolution: incision of main rivers Mammal remains dated to Ma (Bolliger et al. 1996) Reconstructed evolution of base level NTB Dossier III, modified 26 More during tomorrows excursion

27 Long-term geological evolution: Formation of 'ice marginal drainage channels' 27

28 Long-term geological evolution: Formation of 'ice marginal drainage channels' 28

29 Long-term geological evolution: Formation of 'glacial overdeepenings' 29

30 Long-term geological evolution: Formation of 'glacial overdeepenings' 30

31 Long-term geological evolution: Depth top host rock below local base level Depth of Top Opalinuston below local base level 31

32 Geomechanics: Excavation damage zone Geotechnical conditions and need of liner as boundary conditions for safety barriers 32

33 Geomechanics: Depth of repository level below terrain Depth of repository level below terrain 33

34 Stage 2: Sites proposed by Nagra (Dec. 2014) Priority host rock for HLW & L/ILW: Opalinuston Ice marginal drainage channels small overburden Thickness of effective containment zone ( host rock and confining unit ) Unfavourable tectonic situation in the north, large depth in the south (geomechanics) Higher uplift, erosion & neotectonic activity Not explorable with 3D seismics Host rock with smaller self sealing capacity 34

35 35 Site selection phase 3: Final site selection / general license application

36 Exploration program Jura Ost: 3D seismics 3D seismics starting

37 Exploration program Jura Ost: Deep drillholes & Quaternary investigations (e.g. in Lower Aare Valley) Borehole drilling starting ~

38 Exploration program Zürich Nordost: 3D seismics 3D seismics starting

39 Exploration program Zürich Nordost: Deep drillholes & Quaternary investigations (e.g. Thur Valley) Borehole drilling starting ~

40 Next steps in the site selection process Stage 2: Selection of at least two sites for each repository : - Review of Nagra s proposals by: - ENSI (Nuclear Safety Inspectorate) and EGT (Expert Group Geologic Disposal) - NSC (Nuclear Safety Commission) - Federal Offices, Cantons, Regional Conferences - Public hearings - Position and recommendation to the Federal Council by Swiss Federal Offcie of Energy : Federal Council decision on Stage 2 Stage 3: Selection of one site for each repository (with the option of building both repositories at the same site): - Announcement around 2019/ Submission of general license application (around 2022) Followed by a decision of the Federal Council on site selection, a debate in Parliament and an optional referendum at the national level 40

41 thank you for your attention

Geological 3D-model of the Basel region - a tool to explore geopotentials. Dr. Horst Dresmann. Prof. Peter Huggenberger. Dr.

Geological 3D-model of the Basel region - a tool to explore geopotentials Dr. Horst Dresmann Prof. Peter Huggenberger Dr. Janis Epting GeORG technical workshop 18.11.2010, Freiburg 1/24 Where are useable