- 59 - from the centre. Finally, the availability of the BNI's internal communication networks (not designed to SSE standards) cannot be guaranteed. 1.103.4 Loss of heat sink 3.4.1 Experimental reactors Osiris The inspectors found that the filtration systems verified appeared to be satisfactory. The availability of the emergency resources appears to be satisfactory on Osiris and there are degraded mode instructions. The persons concerned would seem to be adequately familiar with the emergency resources. Finally, an inconsistency on the anomaly threshold concerning the optimum filling level of the Osiris pool was identified between the safety report and the instructions on how to respond to an accidental drop in the level of the pool. RHF The reactor can be cooled for several days by natural convection in closed-circuit, by means of the water reserves consisting of the pools in the reactor building. These systems do not require any electrical power supply either, as the water is circulated by natural convection. In normal operation, the inspectors noted that the log of cooling parameters was correctly kept for the RHF. A request in the follow-up letter concerned the availability of the RHF ultimate backup, which needs to be specified, that is the FLS motor-driven pump. The inspections showed that even if maintenance was carried out on the RHF pumps and cooling systems, it was nonetheless inadequately traced, in particular with regard to justifying that the required level of performance is maintained. Although the checks and periodic tests are rigorously managed, especially for tests prior to a new cycle, preventive maintenance of the passive equipment and indeed the equipment as a whole that contributes to seismic resistance needs to be better structured (civil engineering maintenance programme, already requested elsewhere). Phénix It should be noted that because reactor power operations ceased in February 2010, thermal leakage alone is sufficient to remove the residual heat. Forced convection cooling is thus no longer necessary. 3.4.2 Nuclear fuel cycle facilities La Hague site The cooling function is important for safety on the La Hague site. It is necessary in order to control the temperature of the spent fuel stored in the pits, or certain exothermal processes. The licensee is thus required to manage this function and ensure that it is maintained durably and in a post-accident situation. The inspection demonstrated that the procedure for making the transition to safeguard mode by natural ventilation of the ECC (stores of packages of compacted hulls and end-pieces) would be difficult to apply in a real situation. Moreover, the heat insulation of the ventilation ducts in this store is in poor condition and two ventilation dampers were in an inappropriate position. Remarks were made and questions raised concerning the operability of pool water manual makeup resources following an exercise which in particular covered the deployment of the piping, which proved to be difficult and the time needed to install the only cofferdam not pre-positioned to contain the waters below the pools. Similarly, uncertainty existed with regard to the operability of the pool level measurement in post-accident conditions, given the design of the remote bubbler tube. There is also no guarantee of post-accident conditions monitoring of the tank temperatures, in particular in the R1 unit, owing to the potential hazards. The fan coil units for the pool water operate in manual mode (no automation), even though there is provision for an automatic mode. The inspectors asked that the safety of this operating mode be demonstrated.
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