- 228 - As regards the spent fuel pools, the CEA highlights the pools and their sealing system. For the Osiris facility the CEA also identifies water make-up means appropriate for the kinetics of the studied scenario. For the criticality accident situation retained on the JHR, the CEA identifies the racks and cabinets in the pools or storage rooms as key equipment items. For the JHR and Osiris facilities, ASN considers that the CEA has satisfactorily identified the feared situations. It nevertheless considers that the key equipment items and the potential threats to them have been only partially identified, and that beyond the pools, the pile block as a whole and the primary cooling system must be considered as key equipment items. The CEA has made a commitment in this respect. Phénix The feared situations or "degraded states" considered to identify the key equipment items for this facility are: losses of sodium containment that could lead to a sodium fire or a sodium-water reaction; a criticality accident in a spent fuel assembly storage drum; collapse of the hot cells. The CEA considers the following items to be crucial for the prevention of these feared situations: with respect to the risk of sodium containment loss: o the primary cold traps situated in the reactor building; o the primary containment vessel and its supporting structures (to contain a leak from the first two vessels)1; o the primary sodium storage tanks in the reactor building; o the storage drum situated in the storage and handling building (also considered in the context of a criticality accident); o the drum purification system drainage tank; o the drum cold trap; o the secondary sodium storage tanks and the secondary sodium circuit auxiliaries (including the cold traps) situated in the steam generators (SG) building; with respect to the risk of hot cell collapse, the irradiated fuel elements compartment and the auxiliary compartment situated in the handling building. The CEA has also identified the potential threats to the essential equipment, namely : the civil engineering structures of the various buildings, and notably those that could cause a potential domino effect; the SG caissons, the sodium firewalls and the walkways situated in the SG building; crane P1 situated in the reactor building hall; cranes P2 and P4 situated in the handling building. The CEA's list of feared situations considered for the Phénix reactor raises no particular remarks. Reactor operated by the ILL The approach implemented by the licensee consisted in identifying the scenarios that could lead to more serious radiological consequences that those considered when establishing the off-site emergency plan (PPI). The scenarios were established considering all the operating phases, even the very short ones such as placing the fuel element stack in a handling cask when unloading it, or changing the water in the handling cask before unloading the spent fuel element into canal 2 (spent fuel pool). 1 The CEA also assesses the earthquake behaviour of the primary containment cooling system (ultimate backup) insofar as its failure could significantly increase the scale of a sodium-water reaction further to rupture of the primary containment vessel.
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