Architecture and management of a geological repository - Andra

11 – Operational SafetyThe other risks listed do not hold the same degree of importance. Among these, two types of risksrelated to a temporary loss of ventilation in the installations are noteworthy. These are the risk ofexplosion associated with the emission of small amounts of explosive gases from some B wastepackages (B2, B5) which seems improbable given the ventilation throughputs planned for theinstallations which would ensure the dilution of these gases. However, a specific study has beencarried out into this risk in support of this analysis. The risk associated with the presence ofexothermic packages (C waste and spent fuel packages) should also be mentioned even if thetemperatures of the metal envelope of the transfer casks in which they are transported do not exceedapproximately thirty degrees and could not cause burns to personnel.• Risk reduction measuresThe risk reduction depends first of all on prevention, by selecting specially adapted, reliable, wellmaintained equipment fitted with all necessary safety systems, and on training personnel, raisingawareness of the different types of risks encountered, compliance with procedures and on-site trafficregulations and the wearing of personal protective gear. 154 .In the underground installations, the installation of physical protection systems (for work in shafts inparticular), the use of equipment operated from control stations that are some distance from the workface, the equipping of safety networks on work sites (fire-fighting water network, communicationsnetwork, etc.) as they progress also contribute to reduce the risks faced by personnel.Of all the risks mentioned, the risk of fire is different from the others because it has collectiveconsequences and requires specific provision for the evacuation of personnel.In surface installations, the risks of fire are limited: the electric (or electronic) cabinets appear to be themain possible source of ignition. The measures to prevent, detect and limit the consequences of firethat would be used would comply with the Labour Code and the Basic Safety Rules (RèglesFondamentales de Sûreté) RFS I.4.a [108] and RFS II.2 [109]. Feedback on experience of nuclearinstallations with similar functions to those carried out in the repository would also be taken intoaccount. The main provisions concern the choice of fire-retardant materials, the limitation of thecalorific load of the installations (associated with the choice of handling by means of travelling craneor electrically driven vehicle), the sectorisation of areas that present a fire risk and the fire stability ofstructural components. The installation of fire detection systems, control of ventilation with a smokeextraction system and existence of evacuation routes (with clearances protected by overpressure, nonfumigationchambers, etc.) also play a role in the safety of personnel.In underground installations, the principles adopted are those of a ventilation system with smokeextraction and connections between adjacent drifts to facilitate the evacuation of personnel. It is moredifficult to make reference to other existing installations (road/railway tunnels, underground mines) asthe solutions used are specifically related to the configuration of each installation.• SummaryA summary of the analysis (cf. Table 11.2.1) is presented per type of activity (construction, operation,closure). Work associated with the possible retrieval of disposal packages has also been envisaged.154 This personal protective gear includes safety shoes, safety earmuffs, dust-masks and autonomous breathing apparatus (self rescuers) tobe used in the presence of fumes.DOSSIER 2005 ARGILE -ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL DISPOSAL SYSTEM444/495