152.2.4 Development needsFrom a long-term safety point of view, estimating rock mass suitability based on Q'-value is unsatisfactory. It is evident that the Q'-value is inadequate <strong>for</strong> classifyinggeological <strong>and</strong> hydrogeological features significant to nuclear waste disposal.According to current view, resolution of the Q’-system itself is not a problem, but ratherthe general inadequacy of it to detect significant safety features. There<strong>for</strong>e, anotherparameter to describe rock quality <strong>and</strong>/or de<strong>for</strong>mation intensity may there<strong>for</strong>e beneeded. Classification based on hydrogeological data (hydraulic conductivity) frompilot holes is not fully satisfactory either due to uncertainties <strong>and</strong> difficulties incorrelating pilot hole data with tunnel inflow data. In addition, correlating Lugeonvalues <strong>and</strong> different flow measurements proved problematic. Furthermore,hydrogeological zones do not always coincide with the modelled site-scale geologicalstructures 1 , which further complicates the interpretation of pilot hole data. Interpretationof overall hydrogeological conditions of the studied area also dem<strong>and</strong>s extensive1 Highly transmissive features, defined as layout-determining features based on hydrogeologicalproperties, may on some occasions appear as single large fractures <strong>and</strong> are there<strong>for</strong>e not defined asgeological layout-determining features.
16underst<strong>and</strong>ing of site hydrogeology. Finally, there were significant difficulties in takingdifferent flow measurements, particularly in the tunnel probe holes. The hydrogeologicaldata is, nevertheless, important <strong>for</strong> rock suitability classification, thoughusability of the data could probably be increased with method development.The geometrical variations <strong>and</strong> uncertainties of many de<strong>for</strong>mation zones have a greatimpact on implementation of the HRC, especially if the zones are only modelled on sitescale as is currently the case at Olkiluoto. A 3D tunnel-scale de<strong>for</strong>mation zone modelthat integrates both the hydrogeological <strong>and</strong> geological models <strong>and</strong> takes the variablezone geometries into account is there<strong>for</strong>e needed. Large fractures are not considered inthe HRC tunnel scale process, although fracture trace length is an important parameter<strong>for</strong> a nuclear waste repository on the canister scale. There<strong>for</strong>e, it is necessary to exp<strong>and</strong>the tunnel-scale parameters to consider properties <strong>and</strong> orientations of fractures with longtrace lengths. The relationship between the tunnel cross-cutting fractures <strong>and</strong> slickensidedfractures in pilot holes needs to be investigated. Furthermore, the ductilede<strong>for</strong>mation zones <strong>and</strong> rock mechanics issues are not sufficiently taken into account inthe tested HRC. The ductile de<strong>for</strong>mation model describes the variations in the foliationintensity <strong>and</strong> direction, which are in turn directly related to the rock mechanical stability<strong>and</strong> repository planning.The division suggested in the HRC into four suitability classes on tunnel scale seemssomewhat difficult in practice. There<strong>for</strong>e, the procedure <strong>for</strong> determining suitability ofthe rock mass <strong>for</strong> disposal needs to be revised.At present, systematic mapping takes place too far from the excavation front withrespect to availability of the P/O results when planning the excavation. Some practicalarrangements could help to at least partially solve this problem. On the other h<strong>and</strong>, theexcavation time-table within the repository will most likely be looser than withinONKALO.Summarising, in addition to a great need <strong>for</strong> validation <strong>and</strong> st<strong>and</strong>ardisation of sourcedata used in the HRC process, a tunnel-scale 3D model that integrates the geological<strong>and</strong> hydrogeological models is also needed. Also, additional tools <strong>for</strong> data collection areneeded. Furthermore, it is noted that, while the HRC testing revealed severaldevelopments needs concerning the practical applicability of the HRC, it is alsonecessary to improve the link between long-term safety targets <strong>and</strong> the actual criteria.This latter aspect is the focus of development of the <strong>RSC</strong> criteria described in Section5.3.2.3 SKB approachThe disposal concept to be used in Sweden <strong>and</strong> in Finl<strong>and</strong> is the same. There<strong>for</strong>e,especially requirements of the host rock related to long-term per<strong>for</strong>mance of engineeredbarriers will, to a large extent, be similar. Still, there are site specific features <strong>and</strong>differences in available site data to be considered in development of the practicalcriteria. Due to the similarities, the concept of safety functions, safety functionindicators <strong>and</strong> safety function indicator criteria presented by SKB in SR-Can (SKB2006) is highly relevant to this work. By introducing these concepts, transparencybetween long-term safety <strong>and</strong> any practical criteria can be enhanced. The concepts aredefined as follows:
- Page 1 and 2: Working Report 2009-29RSC-Programme
- Page 3 and 4: ABSTRACTPosiva Oy, jointly owned by
- Page 5 and 6: PREFACEThis report presents the out
- Page 7 and 8: 26 ENGINEERING TARGETS ON HOST ROCK
- Page 9 and 10: 4Reference DesignThe discussion in
- Page 11 and 12: 6approach is presented in (Chapter
- Page 13 and 14: 8shall be estimable and be consider
- Page 15 and 16: 10ScaleParametersRepository scaleLa
- Page 17 and 18: 12Pilot hole dataThe logging of pil
- Page 19: 14determined on the basis of hydrau
- Page 23 and 24: 18ensured to have by design at the
- Page 25 and 26: 20SafetyconceptSiteReferenceDesignT
- Page 27 and 28: 22Safety functionsPerformancetarget
- Page 30 and 31: 254 LONG-TERM SAFETY RELATED REQUIR
- Page 32 and 33: 27The above are referred to as the
- Page 34 and 35: 29A summary of safety function indi
- Page 36 and 37: 31The results by Börgesson and Her
- Page 38 and 39: 33Performance target Target value R
- Page 40 and 41: 35Even this inflow would need to co
- Page 42 and 43: 37form a continuous path along the
- Page 44 and 45: 39Performance targets related to ch
- Page 46 and 47: 415 DEVELOPMENT OF THE ROCK SUITABI
- Page 48 and 49: 43The objectives and the scope of t
- Page 50 and 51: 45not only should high transmissive
- Page 52 and 53: 47next stage of the project, though
- Page 54 and 55: cumulative percent49100908070Tsum0-
- Page 56 and 57: 51Based on the reasoning above, the
- Page 58 and 59: 53averagely fractured rock are avoi
- Page 60 and 61: 55The utilised borehole data consis
- Page 62 and 63: 575.2.4 ResultsLayout determining f
- Page 64 and 65: 59The brittle deformation zones BFZ
- Page 66 and 67: 61In the future, after increased in
- Page 68 and 69: 63Widths of the deterministic influ
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65Determining the influence zone of
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68Respect distance volumeFault pair
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735.2.5 Uncertainties in layout det
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75Hydrogeological propertiesPerform
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77Performance target: Limited conce
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79any influence on the behaviour of
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81~ 350 m30252425262320FPIs/100 m15
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83In the post-closure and glacial p
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85the cores of the zones, the T-val
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87example, 100 metres would have an
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89proposed criteria and to the eval
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91needed in order to assess effects
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93The classification process and th
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95was based on the latest DFN descr
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98described above. After a discussi
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100and shafts can pass through (as
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102orientation in terms of principa
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104influence zone of the structure.
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106Requirement in the E.5 (Draft 3)
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108be carried out at repository lev
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110hydraulical importance that shou
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112
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114Degueldre, C., Triay, I., Kim, J
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116Milnes, A.G., Aaltonen, I., Kemp
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118STUK. 2001. Long-Term Safety of
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