Dimensioning study of EPR2 fuel pool cooling system

Sammanfattning: The PTR system allows the EPR2 fuel pool to be cooled. The evacuation of the residual power fromthe pool is ensured by several heat exchangers and pumps, which have to be dimensioned in order to meetdifferent requirements.In order to dimension them, the worst-case scenario of the components must first be determined.Sensitivity to external conditions and efficiency studies enable to propose a heat exchanger design tomeet the requirements. A parametric study then allows to study more precisely the influence of thegeometry of the exchanger on the heat transfer. This allows to guide the conception of a CFD study ofthe design on the Comsol software in order to validate it. The proposed design can then be integratedinto the PTR cooling train. The train is modeled with FloMaster, in order to compute the head losses inthe hydraulic system and to propose a pump altimetry preventing cavitation.The dimensioning case of the exchangers corresponds to the operating case of the PTR trains duringunit shutdown, while the scenario that facilitates cavitation corresponds to the boiling of the fuel pool.The temperature of the cold source RRI is a sensitive data for the operation of the exchangers. In addition,the placement of the baffles and the space between the tubes play a determining role in the heat removal.It was difficult to construct the desired exchanger geometry in CFD. A compromise model was thusidentified and studied in CFD. The FloMaster study showed that the pressure drop in the PTR network isabout 15.5 mCE at the considered flow rate. Cavitation in a main train is not a problem if the pumps arelowered by at least 1.8 meters from the pool suction point.The sizing study therefore allowed us to propose a heat exchanger design close to the specifications,but this could not be precisely studied in CFD. The pressure drop study allowed to propose a pumpaltimetry preventing cavitation.