Architecture and management of a geological repository - Andra

11 – Operational SafetyThe following conclusions can be drawn from this table:- The analysis shows no notable differences as regards the nature of the risks between packageemplacement and removal. Operations associated with the possible removal of packages from therepository would be the reverse of operations carried out during emplacement;- Closure activities do not present risks associated with the handling and transfer of the packages.On the other hand, special attention will be necessary to counter the possible failure ofradiological protection during operations carried out at the entrance of disposal cells;- The analysis lists conventional risks such as radiological protection failure for which thepreventive measures and controls are known and do not require special studies to be undertaken atthis stage in the project;- It may also be considered that the risks of a package falling and fire in surface installations do notjustify additional studies at this point given the feedback on experience available from similarexisting surface nuclear facilities;- The radiological risks associated with the transfer and emplacement of packages in the disposalcell, on the other hand, have called for further study. The risks induced by transport or handlingvehicle fires must take into account their characteristics and the fact that the fire would occur in asemi-confined space. Similarly, package drop scenarios refer to drop heights that are differentfrom the usual handling heights in surface installations, in particular during transfer cask transferin shafts. These various risks will be dealt with respectively in Sections 11.5 and 11.5 for fire risksand Sections 11.7 and 11.8 for risks associated with drops.11.2.3 Risks associated with the repository external environment11.2.3.1 EarthquakeThe sector covered by the study is a low seismic activity zone. The surface installations would have tobe dimensioned in accordance with current aseismic regulations. In addition, measures would have tobe taken to prevent any loss of safety function liable to have a radiological impact on operatingpersonnel and the public.The measures consist of dimensioning buildings (stability of all buildings) for a safety margincomputed earthquake [112] in order to protect the sources inside these buildings and equipment whichcould, directly or indirectly, be a cause of dissemination of radioactive material.Underground engineered structures withstand seismic loads better than surface installations due toattenuation with depth. It has been shown that the earthquake [36] would not have a significant impactdeep underground.11.2.3.2 Meteorological risksThe main risks only concern surface installations and have no impact on underground activities. Theymainly concern rain and snow fall, extreme temperatures, lightning and wind.11.2.3.3 Aircraft impingementIndependently of the direct physical consequences, the impingement of an aircraft on surfaceinstallations could result in the loss of safety functions leading to the exposure of personnel toradiation and its release into the environment.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM452/495