Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
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7 - Spent fuel <strong>repository</strong> zone7.4.2.2 Assessment <strong>of</strong> the total running length <strong>of</strong> h<strong>and</strong>ling driftsSpent fuel <strong>repository</strong> compactness in a h<strong>and</strong>ling drift depends on the distance (pitch) in between twoneighbouring cells. As the spent fuel packages release heat, this distance is primarily subject to theapplication <strong>of</strong> the thermal criterion for the presence <strong>of</strong> the engineered barrier around the disposalpackages (90°C).Very close results have emerged from preliminary calculations to test the sensitivity <strong>of</strong> this distance atvarious estimated thermal characteristics for French granites.For distances 12 <strong>and</strong> 15 m between two cells, <strong>and</strong> cooling periods <strong>of</strong> 50-70 years for referencepackages CU1 <strong>and</strong> 70-90 years for reference packages CU2, the thermal interference reaches itsmaximum at the midpoint in between 2 disposal cells a few centuries after the package temperaturehas dropped below 90°C, [42].7.5 <strong>Architecture</strong> <strong>of</strong> the spent fuel <strong>repository</strong> zoneThe spent fuel <strong>repository</strong> zone includes the <strong>repository</strong> modules for reference packages CU1 <strong>and</strong> CU2(distributed over two levels) <strong>and</strong> their connecting infrastructures.A disposal module comprises a set <strong>of</strong> h<strong>and</strong>ling drifts served by a shared cluster <strong>of</strong> connecting drifts, asspecified for the vitrified C waste <strong>repository</strong> zone.The disposal capacity <strong>of</strong> each <strong>repository</strong> module depends on the number <strong>of</strong> h<strong>and</strong>ling drifts which canbe sited in the host granite block, whose geometry has been determined by previous explorationworks.This section presents the dimensioning elements, followed by a description <strong>of</strong> the modules in the<strong>repository</strong> zone. It gives a preliminary assessment <strong>of</strong> how many modules need to be constructed <strong>and</strong> <strong>of</strong>the necessary area for spent fuel disposal on the basis <strong>of</strong> the inventory model.7.5.1 Dimensioning elements <strong>of</strong> a <strong>repository</strong> moduleDimensioning a spent fuel disposal module is subject to identical considerations to those that prevailfor C waste modules:- the distance between two adjacent drifts equal to three times the drift width (that is about fifteenmetres) to avoid any mechanical interference;- the distance <strong>of</strong> 12-15 metres between adjacent cells to avoid thermal interference between cells;- the buffer distance from several tens <strong>of</strong> metres up to one hundred metres, between the excavatedstructures <strong>and</strong> the potentially water-conducting fractures at the host block limits (this range coversall foreseeable situations in the French context).Dossier 2005 granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY212/228
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