Architecture and management of a geological repository - Andra

4 – Waste disposal PackagesTo achieve this, dynamic simulations of the fall have been produced by a finite-element calculationwith an assessment of the load resulting from the impact. A reducing coefficient of behaviour isapplied to constraints produced by the finite-element calculation, to take account overall of thedissipation of energy linked to local crushing. This coefficient is established by analogy with seismicbehaviour studies. Simulations have been performed on waste disposal packages with and withoutreinforcements. The results of these calculations show that primary waste package containment ismaintained for the majority of packages, with slight damage to some primary waste packages, and thatthe waste disposal package lid does not open even when damaged (see § 11.8). A fall test programmefor container demonstrators is in progress in 2005 to confirm the conclusions of these simulations.4.1.3.3 Handling interfaceThe principle of package handling in the repository waste disposal cells is based on using a type offork-lift truck (see § 9.3.2). The forks take hold of the disposal container via two housings set into thepackage thickness. The cross sections for the fork housings are standardised at 200 millimetres by200 millimetres approximately.The inter-axial distance between the forks may be standardised. Two types of packages are envisagedfrom this viewpoint. The lighter packages (weighing between 6 and 15 tonnes) holding four primarypackages (as packages B2 and B5) have a standardised inter-axial distance between forks of950 millimetres. The heavier packages (between 15 and 25 tonnes approximately) holding one, two orfour primary packages have a standardised inter-axial distance between forks of 1,600 millimetres.4.1.4 Variant with enhanced retention capabilityAs indicated in § 4.1.2.3, the study of a variant aims to evaluate the possibility of making use over thelong term of the waste disposal package concrete retention capability.One possible method of producing this variant is described below, based on the B.5.2 waste packagetype (package with hulls and end caps and compacted metallic technological waste), representative ofthe most active B waste packages containing long-lived activation and fission products ( 94 Nb, 93 Zr inparticular).4.1.4.1 DescriptionThis variant differs from the previous one in that it uses a single formulation of concrete for all thepackage components, there are no steel reinforcements, these is reinforcement by fibres and it has aspecific closing method. The lack of steel reinforcement favours the durability sought for thiscontainer but implies a higher fibre content to ensure mechanical strength.The method considered for production of this variant is to include a pre-fabricated body withcompartments adjusted to the size of the primary packages, comparable to the standard package. Thecontainer is closed by four independent lids poured into the upper part of each of the four housings inthe body. Prior to pouring the lid, a pre-fabricated, conical plug (with the purpose of blocking thefunctional clearance) is placed above the primary package in each housing. Using pre-fabricated plugssimplifies any eventual recovery operation of the primary packages and guarantees a good mechanicalconnection above the residual voids in the housing.The pre-fabricated body and the four poured lids are manufactured from a same high-performanceconcrete with stainless fibres (90 MPa minimum, see below). Stainless is chosen to limit the risks ofcorrosion.This variant is illustrated below (Figure 4.1.6). It is about 1.50 metres wide and long and 2 metres high(package type B5.2). Its total weight (full container) is around 12 t.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM118/495