Nuclear Waste Management Decision-Making Support with MCDA

Table 4

(a) Safety and performance indicators tested in the SPIN project [20]

Safety indicators

Performance indicators

Effective dose rate Sv/y; Radiotoxicity concentration in biosphere water Sv/m^3; Radiotoxicity flux from geosphere Sv/y; Radiotoxicity outside geosphere Sv; Time-integrated radiotoxicity flux from geosphere Sv; Relative activity flux from geosphere —; Relative activity concentration in biosphere water —

Activity in compartments Bq; Activity outside compartments Bq; Activity flux from compartments Bq/y; Time-integrated activity flux from compartments Bq; Activity concentration in compartment water Bq/m^3; Radiotoxicity in compartments Sv; Radiotoxicity outside compartments Sv; Radiotoxicity flux from compartments Sv/y; Time-integrated radiotoxicity flux from compartments Sv; Radiotoxicity concentration in compartment water Sv/m^3; Transport time through compartments y; Portion of not totally isolated waste —; Time-integrated flux from geosphere/initial inventory —; Concentration in biosphere water/waste package water —

(b) IAEA: examples of performance and safety indicators [10]

Indicator	Source	Application	“Yardstick”
General performance indicators
Radionuclide transfer times	Quantitative evaluations of parts of total system	Engineered barriers (e.g., clay backfill) or geosphere	Radionuclide half-lives
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)
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
Age profile of groundwater	Site characterization paleohydrogeology	Geosphere	Time-scale of assessment
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
Safety indicators
Risk	Assessment model results	Human beings	Risk limit or constraint
Dose	Assessment model results	Human beings	Dose limit or constraint
Environmental impact	Assessment model results	Other species	Environmental protection standards
Complementary safety indicators
Radionuclide concentrations outside the near field	Assessment model results	Accessible environment	Levels of corresponding natural concentrations
Radionuclide fluxes outside the near field	Assessment model results	Accessible environment, geosphere-biosphere interface	Corresponding natural fluxes
Containment times	Experiments, technical specifications, and/or process model calculations	Canisters/containers, engineered barriers, or geosphere	“Crossover times,” for hazard indices