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Indicator | Source | Application | “Yardstick” |
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General performance indicators |
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Radionuclide transfer times | Quantitative evaluations of parts of total system | Engineered barriers (e.g., clay backfill) or geosphere | Radionuclide half-lives |
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Radionuclide concentrations in the near field | Assessment model results | Engineered barrier system | Subsystem criteria derived from sensitivity analyses (“relative” comparisons between different analyses may also be of value, see main text) |
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Characteristics that control “dilution” in time and space (e.g., waste-form dissolution or release rates, canister failure rate, and porosities) | Experiments, technical specifications, and/or process model calculations | Engineered barriers or geosphere | Criteria derived from total system performance-assessment calculations |
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Age profile of groundwater | Site characterization paleohydrogeology | Geosphere | Time-scale of assessment |
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Other physical-chemical properties of the disposal system (e.g., water package loading, buffer composition and density, fracture frequency, and lack of exploitable mineral resources | Experiments, technical specifications, and/or process model calculations | Engineered barriers or geosphere | Subsystem criteria developed by the regulatory authority or by the operator |
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Safety indicators |
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Risk | Assessment model results | Human beings | Risk limit or constraint |
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Dose | Assessment model results | Human beings | Dose limit or constraint |
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Environmental impact | Assessment model results | Other species | Environmental protection standards |
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Complementary safety indicators |
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Radionuclide concentrations outside the near field | Assessment model results | Accessible environment | Levels of corresponding natural concentrations |
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Radionuclide fluxes outside the near field | Assessment model results | Accessible environment, geosphere-biosphere interface | Corresponding natural fluxes |
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Containment times | Experiments, technical specifications, and/or process model calculations | Canisters/containers, engineered barriers, or geosphere | “Crossover times,” for hazard indices |
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