Application of the Spanish methodological approach for biosphere assessment to a generic high-level waste disposal site

Uncertainty and sensitivity analysis of radionuclide migration through the engineered barriers of deep geological repository: Case of RBMK-1500 SNF

“…Besides various assessment-endpoints, the UA and SA results differ with their context (specifics of systems design (engineered barriers, geological environment, and ecosystems), system evolution scenarios, etc.). For instance, in [5], the assessment of human exposure due to unit release (1 Bq/yr) to well was considered where contaminated well water was used for drinking by humans and their livestock and for irrigation of soils), while in [6] the source term of contaminants was assumed to be contaminated river water which was used for the livestock, irrigation and drinking. With various model output being analysed, different system evolution and radionuclide transport scenarios being considered, case specific ranking of the most important parameters is usually reported.…”

“…Based on correlation analysis, the biosphere dose conversion factor (BDCF) of 135 Cs is mostly influenced by sorption coefficient in soil, precipitation, the transfer coefficients from soil to cereals, potatoes, and pork, the consumption of potatoes, etc., while in the case of BDCF of 79 Se, the sorption coefficient in soil, precipitation, the transfer coefficients from soil to cereals, chicken, and pork were the dominant parameters. Parameter importance ranking was also based on regression/correlation analysis in [6]. In the case of the geological repository at Yucca Mountain to be located in unsaturated conditions and in the case of nominal scenario class, MC approach with LHS sampling was considered for UA and SA analysis [8].…”

“…For the parameter sensitivity analysis within the context of geological disposal, the standardized linear regression, correlation analysis is used widely ( [5], [6], [7], [9], [20], [21], [22]). The standardized regression coefficients (SRC), correlation coefficients (Pearson, partial correlation coefficients), Spearman rank correlation coefficients (RCC) could serve as sensitivity measures.…”

“…These applications vary a lot as they depend on the specific objectives set for the analysis, disposal system design, regulatory requirements, etc. The published results of UA and SA indicate their application on different scales (e.g., near field ( [3], [4]), far field, biosphere ( [5], [6]), total system ( [7], [8])). For instance, in [3], the impact of parameter uncertainties on the radionuclide flux from the engineered barriers of the Swedish repository for SNF was analysed.…”

“…In the case of geological repository at Yucca Mountain in Nevada (USA) for the disposal of high-level radioactive waste, the regulatory criteria for the evaluation of system safety is defined in terms of mean and median dose to the reasonably maximally exposed individual, thus extensive (with 392 epistemically uncertain variables) UA and SA were carried out to evaluate dose uncertainty and the main contributors to its uncertainty [8]. On the other hand, other studies, such as reported in [5], [6], are oriented to the uncertainty of various parameters of radionuclide transport in biosphere and human related parameters and their impact on the resulting exposure dose (and flux to dose conversion factors subsequently). The published results of uncertainty and sensitivity analysis within the context of repository performance also indicate that different model outputs are being analysed (peak flux [3], released amount of radionuclides at particular times [4], peak dose [7], dose over time [8], as well as physical parameters influencing the further transport of the contaminant to environment (e.g.…”