- 298 - The times estimated by the licensee to reach the significant stages in the accident sequence starting from the total loss of the electrical power supplies and cooling are summarized in the following table: Estimated time to reach (hours) Start of boiling Water surface at the level of the top of the fuel assemblies Fuel cladding temperature at 500°C (start of deterioration) Total evaporation 52 hours 253 hours >310 hours >500 hours Times associated with the transients of total loss of electrical power supplies and cooling for the pools The loss of the cooling function for the fission product tanks would lead to: an increase in the temperature of the solutions contained in the tanks; attainment of the boiling temperature of these solutions; entrainment of the radioactive drops by the vapour produced; release of radioactive materials. According to the licensee, the times for the solutions contained in the identified equipment to reach boiling point in the feared situations can be estimated as follows: Unit Equipment Time before boiling T2 Concentrated FP solution storage and transfer tanks 17 hours SPF5 and SPF6 Concentrated FP solution transfer tanks 17 hours T7 Concentrated FP solution storage tanks 25 hours SPF5 and SPF6 Concentrated FP solution storage tanks 25 hours R7 Concentrated FP solution storage tanks 28 hours T2 FP condenser evaporator 44 hours R2 FP condenser evaporator 65 hours Times to reach boiling point in the event of loss of cooling for the FP tanks
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