Architecture and management of a geological repository - Andra

3 – High Level Long-Lived WasteConditioning for assemblies has been studied (see Chapter 4, § 4.3). This allows for a receipt of bareassemblies or those placed in claddings prior to receipt.3.2.3.1 PWR fuel assembliesThe reference fuel assembly corresponds to an advanced second-generation FRAGEMA assemblywith thicker guide thimbles and zirconium alloy cladding. It is illustrated in Figure 3.2.19. It is calledAFA-2GE for the PWR 900 MWe reactors and AFA-2LE for the PWR 1300 MWe and 1450 MWereactors.Figure 3.2.19PWR fuel assemblyThe assembly comprises a rigid metallic structure (skeleton) supporting 264 geometrically-identicalrods distributed through a square lattice of 289 compartments.The skeleton is made up of the following components:- 2 fabricated end pieces, fixed by guide thimbles at each end, maintaining the position in the core;- 24 tubes to guide the cluster rods (guide thimbles) and support the grids making up the structuralframework;- 1 central instrumentation tube with the sole task of guiding a flow measurement micro-chamber;- 8 (AFA-2GE) or 10 (AFA-2LE) spacing grids to hold the rods axially and radially using a softhardstop assembly.The fuel rod is made up of:- closed cylindrical, metallic cladding closed top and bottom by two welded plugs (the upper plughas a pressurisation hole which is plugged after the rod is filled with helium);- stack of fuel pellets 95% of the way up the rod;- a helical spring in the upper part of the fuel pellet stock holding it axially during handlingoperations.The AFA-2GE and AFA-2LE assemblies have identical configuration (lattice 17x17 with 12.6 mmintervals, section 214 mm x 214 mm), but different total lengths: 4.12 metres for AFA-2GE and 4.87metres for AFA-2LE (dimensions after irradiation). Material weights vary according to the type of fueland type of assembly. They are given Table 3.2.4.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM95/495