Architecture and management of a geological repository - Andra

3 – High Level Long-Lived WasteTable 3.2.4Weight of PWR fuel assemblies (per material and total weight)Material weight per assembly (in kilograms)Nickel alloy(end piecesprings andgrids)Assembly Ceramic fuel Zirconiumalloy (rodcladding)Stainlesssteel (endpieces, rodsprings, etc.)Total weight ofassembly)(in kilograms)AFA-2GE 521.2 (UO 2 ) 125.6 2.1 16.4 665UOX/UREAFA-2LE UOX 608.1 (UO 2 ) 146.2 2.5 19.5 775AFA-2GE MOX 513.9 ((U-Pu)O 2 ) 125.6 2.1 18.1 660One of the problem areas of the fuels with respect to the disposal study, in common with vitrified Cwaste, is their considerable thermal release linked to their radiological inventory. One differencecompared with vitrified waste is the major contribution made by plutonium to fuel thermicity; thisresults in a longer heat transfer phase, due to the period of the involved isotopes, mainly americium-241 ( 241 Am), a daughter product of plutonium-241 ( 241 Pu).Changes over time in the residual heat rating of the UOX and MOX assemblies, after unloading fromthe reactors, is illustrated in Figure 3.2.20Puissance Thermal thermique power (watt (Watt per parassemblage)assembly)3000280026002400220020001800160014001200100080060040020000 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300Durée Cooling de refroidissement time (years) (an)Assemblage UOX AFA-2GEUOX AFA-2GE assblyAssemblage UOX AFA-2LE UOX assbly AFA-2LEAssemblage MOX AFA-2GE MOX assbly AFA-2GEFigure 3.2.20Changes in residual heat rating of UOX and MOX fuel assembliesIn the previous figure, the heat ratings are deducted from the UOX and MOX fuel radiologicalinventories. For noted UOX AFA-2GE and UOX AFA-2LE assemblies, an envelope inventory hasbeen defined for a mixture of UOX2, UOX3 and enriched recycled uranium fuels. For the studies, notethat the PWR spent fuel disposal packages group four assemblies for the UOX AFA-2GE or UOXAFA-2LE fuels (see Chapter 4, § 4.3).3.2.3.2 CEA fuels (research and national defence reactors)Alongside the scenarios described above, the CEA fuels are quite diverse. They include (i) fuels fromNUGG reactors, (ii) fuels from the EL4 heavy water reactor, (iii) fuel elements from the Célestinreactors installed at Marcoule and (iv) nuclear propulsion fuels from land-based reactors or those onboard ships.The NUGG fuels correspond to a residual tonnage of non-reprocessed fuels, around 15 tonnes. Theyare currently conditioned in cylindrical claddings 88 or 130 mm in diameter and equal to 655.5 mmhigh. These claddings contain a very small amount of waste, 9 or 18 kilograms on average dependingon the type of cladding. They have a particularly low heat rating of around 3 watts maximum.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM96/495