Architecture and management of a geological repository - Andra

3 – High Level Long-Lived WasteThe physico-chemical characteristics of the conditioned waste have tremendous influence on thedesign choices, so that the packages are placed in favourable environmental conditions to limit theiralteration over time. They determine the initial and long-term containment capability of the packagesand disturbances potentially caused by their degradation. These disturbances include (i) the release ofproducts likely to increase the solubility of the radionuclides or complex a significant number, (ii) theproduction of gas by radiolysis or corrosion of materials and (iii) the formation of potentiallyaggressive species on the surrounding materials. Packages containing organic waste are singled out.Gaseous releases are input data for the study of the ventilation of facilities, disposal packages and forthe risk analysis in the operating and observation phases.Container characteristics (dimensions, weights, gripping systems) are important parameters indesigning disposal packages, architectures and operating methods.The thermal data are used for (i) thermal design of the repository and (ii) an assessment of itsbehaviour. The irradiation level of the packages plays a part in designing the radiological protectionmethods, based on the radiological protection objectives adopted.The inventory model defines the number of primary waste packages for each waste package type takeninto account in the study, including their total volume, for every scenario S1a,b,c and S2 introduced inSection 3.1.3.3.1 Choice of waste package type, nomenclature used subsequentlyThe various groups of primary packages presented in Section 3.2 differ in (i) the thermal release levelof the packages (B waste with nil to moderate thermicity, vitrified C waste and spent fuels with greaterthermicity) and (ii) the waste type and conditioning methods.Sixteen reference packages have thus been identified at level 1 of the inventory model hierarchy treeby the package grouping possibilities. These include:- eight B waste reference packages, graded B1 to B8, corresponding to Sections 3.2.1.1 to 3.2.1.7,differentiating between cemented cladding waste and compacted cladding waste (§ 3.2.1.4);- give vitrified C waste reference packages, graded C0 (§ 3.2.2.1), C1 and C2 (§ 3.2.2.2), C3 and C4(§ 3.2.2.3);- two PWR spent fuel reference packages, graded CU1 and CU2 (differentiating between UOX andMOX fuels, § 3.2.3.1), to which is added reference package CU3 (grouping all the other fuels witha far lower thermal release).As indicated above, some of these reference packages are sub-divided, into level 2 and level 3reference packages.Thus, B2.1 and B2.2 reference packages single out packages with different geometries.B3 reference packages, grouping a wide range of package families, are listed on two levels. Packagegroupings at level 2 have been defined based on the materials used for the containers and thehomogenous or heterogeneous nature of the conditioned waste:- B.3.1: heterogeneous waste contained in concrete envelopes;- B.3.2: homogenous waste contained in concrete envelopes;- B.3.3: heterogeneous waste contained in metallic envelopes;The level 3 reference package listing corresponds to the taking into account of the chemical nature ofthe waste, the risk of hydrogen production and the package dimensions (level 3 reference packagesassociated respectively with level 2 reference packages: B.3.1, B3.2 and B.3.3 are classified byascending size order):- B3.1.1, B3.1.3, B3.2.1, B3.2.2, B3.3.2: packages potentially generating hydrogen;- B3.1.2, B3.3.1, B3.3.3, B3.3.4: packages containing organic matter and generating hydrogen.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM98/495