- 325 - radiation design basis: taking core meltdown in air when hot as the reference scenario; redundancy of all the backup means, including the necessary utilities (electrical power supplies in particular). For this new PCS, the ILL has undertaken to: provide an uninterruptible power supply (UPS) for the equipment items involved in facility monitoring from this PCS 3; detail the design of the PCS 3 with respect to hazards associated with the industrial environment and the communication routes, and specify its functional requirements. The ILL underlines that the PCS 3 will be permit the management of all types of emergency (nuclear, seismic, flood, combined hazards) and will be designed so as to allow the utilisation of all the new backup systems presented earlier in this report (CRU, CES, CDS, CEN). Pending PCS 3's entry into service, and to improve the current situation, the licensee has planned to install, during the winter 2011-2012 shutdown, an additional emergency diesel generator set. In the event of site flooding, this generator will be capable of resupplying the normally backed-up electrical power supplies, allowing monitoring of the reactor and deployment of emergency means such as a motor-driven pump. The ILL has undertaken to specify the functional requirements of this additional emergency diesel generator set. It has also undertaken to examine the possibility of emergency takeover of the electrical power supply necessary for monitoring the facility from the PCS to cope with a starting failure of the dedicated diesel generator set after an earthquake. The ILL has moreover undertaken to: add a fixed earthquake-qualified neutron detector in the pool that will deliver information to the future PCS 3 to inform operators of the critical state of the core should it be damaged in the pile block or the pool; install two passive autocatalytic hydrogen recombiners at the top of the containment and the top of the structural steelwork of the cold neutron source; install instrumentation that provides reliable information on residual power removal in the event of an earthquake exceeding the SSE (for an earthquake equal to SSE + ); install earthquake-qualified instrumentation (qualified to a level at least equal to SSE + ), enabling an accurate characterisation of the radiological activity of environmental releases in an accident situation, take measures to ensure the availability of the meteorological and environmental radiological monitoring data; supplement its demonstrations concerning the impact of an earthquake-induced fire or explosion. It has also undertaken to: continue its reflection on the integration of the organisational and human aspects in accident situations; examine the operability of the method of alerting and deploying its emergency teams in the extreme external hazard scenarios studied in the CSAs take measures to guarantee the reinforcement of the emergency organisation with means from outside the BNI The ILL has also planned buying satellite telephones. ASN considers that the proposed measures must be implemented, the major improvement being the creation of a new PCS (PCS 3) taking into account the hazard risks studied in the CSA. ASN will issue requests to the ILL in this respect.
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