Architecture and management of a geological repository - Andra

3 – High Level Long-Lived WasteRadiological activity is due (i) to activation products from neutron activation of the alloy componentsand impurities making up the component materials of the assembly structures during their time in thereactor and spread in the mass of these materials, and (ii) contamination by fission products, impurityactivation products and actinides found in the oxidised layer covering the internal surface area of thecladding lengths that held the fuel. This contamination is also caused by traces of undissolvedsubstances that may be left after the waste has been rinsed. The radiological contribution fromtechnological waste found in some packages is negligible compared with that of the cladding waste.Package thermicity is mainly caused by cobalt-60. A decrease in cobalt results in some packageslosing their thermicity given the age of the waste.Other packages have a heat rating in the order ofaround thirty watts when they are produced, but this drops rapidly after a few years, in conjunctionwith the decrease in cobalt. These changes are illustrated in Figure 3.2.12.30,0Thermal power (watts per package)Puissance thermique (Watt par colis)25,020,015,010,05,0Colis primaire contenant desPrimary packagesdéchets de structure decombustiblescontainingREPcompactedUOX, URE etMOX, cladding compactés waste0,01 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59Age of package Age du (years) colis (an)Figure 3.2.12Changes in residual heat rating in cladding waste primary packages from PWRUOX, enriched recycled uranium and MOX fuels• Cemented cladding wasteThe cladding waste from the PWR fuel assemblies is initially cemented into huge stainless steeldrums. This process was applied between 1990 and 1995, then replaced in 2002 by waste compacting,in the Hull Compacting Workshop at La Hague.Packages produced between 1990 and 1995 are called drums of cemented hulls and end caps (seeFigure 3.2.13).DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM86/495