Architecture and management of a geological repository - Andra

11 – Operational Safety11.5.1.3 Results related to a fire on the transfer transfer cask, the disposal package and thewaste package of bituminised sludge (B2)Table 11.5.2 shows the results of the fire simulation with the maximum temperatures which would bereached at the external surfaces of the transfer transfer cask, the disposal package and the primarypackages. It also gives the duration required from the outbreak of the fire to reach this maximumtemperature.Table 11.5.2Transfer transfercaskDisposal packagePrimary packageTemperatures estimated at the transfer transfer cask, the disposal package andthe primary package of bituminised sludge (B2) obtained by numericalsimulations under fire conditionsMaximum temperaturereached (°C)Time to reach Tmaxfrom the outbreak ofthe fireLower surface 900 ~ 1 hSide surfaces 455 ~ 2 hUpper surface 127 ~ 1 hAccording to thesurfacefrom 203 to 561~ 3 hContainer body 143 (in lower surface) ~ 16 hWastes < 120 (except in package base) ~ 16 hThe simulations show that there isn’t any risk of igniting the bituminised sludge wastes because theintegrity of the transfer cask, the disposal package and the envelope of the primary package ispreserved, preventing any contact by a flame with the bituminised matrix. Spontaneous combustion ofthe bituminised products, which requires a temperature on the order of 350°C, is also impossible. Theonly consequence of the fire on the wastes would be a softening of the bituminised matrix.The temperatures determined show that the transfer cask could be slightly affected from a mechanicalviewpoint because of its large thickness.Thanks to the protective effect of the thermal shield incorporated in the transfer cask’s structure, theconcrete envelope of the disposal package would be subjected to temperatures on the order of 500°C,which would not effect the waste package integrity.The metallic envelope of the primary packages, which is not thermally affected by maximumtemperatures on the order of 150°C (cf.Figure 11.5.1), would not be damaged by the fire.Therefore, these results refute the assumption of a deterioration of the primary waste package and aloss of containment.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM466/495