Architecture and management of a geological repository - Andra

11 – Operational SafetyFigure 11.4.5Fire in a dead-end drift: personnel evacuation via an interconnecting drift intoan adjacent drift or sheltering in a mobile refugeIn all the above scenarios, personnel must then head via connecting galleries supplied with fresh air tothe personnel transport shaft in order to return to the surface.11.4.2 Simulation of personnel evacuation conditionsThe results of these preliminary simulation studies are presented, as before, by type of fire as thepersonnel evacuation conditions are directly linked to whether or not smoke layering occurs.11.4.2.1 Fire with smoke de-layeringThe example given is a machinery fire with a thermal power of 15 MW in a type C cell access driftduring nuclear operation. This power represents the maximum power of the machinery used.The example used is that of a fire just after an intersection, which corresponds to a maximumevacuation distance before reaching the next interconnecting drift of almost 200 m.The data obtained 170 (temperature, carbon monoxide concentration and air/smoke mixture opacity) arecomparable with the permissible thresholds for survival and escape conditions for this type of fire. Thetemperature shall not exceed 80°C for more than 15 minutes. The carbon monoxide content shall notexceed figures within a range estimated at between 500 ppm for 60 minutes and 3000 ppm for10 minutes. Finally, an opacity greater than 0.3 m -1 corresponding to a walking visibility of 7 m startsto hinder personnel evacuation; it becomes difficult with an opacity greater than 1 m -1 (visibility lessthan 1.5 m).The results of the simulations are presented, emphasising personnel evacuation conditions inaccordance with two assumptions: the normal evacuation speed is 1 m/s; that of a group having toevacuate a casualty would be 0.5 m/s.170 The temperature changes have been calculated by applying the thermal convection laws in a turbulent air flow. The changes in opacityand the carbon monoxide concentration were digitally simulated, as for the temperature, using the Camatt (tunnel transient anisothermalmonodimensional computation) software.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM461/495