Sizes of each heat exchanger are given in Table 3. Volumes have been calculated using the Gnielinski correlation because of the better results achieved in the LTR and the precooler, between each correlation and the CFD results. The LM is a novel proposed heat exchanger developed for fusion reactors [10] so it cannot be com-pared with the rest of heat exchanger. The ratio of the total heat load to the volume depends on the thermal properties of the flu-ids and the thermal approach. So, as recuperators (BBR and LTR)work with CO2to CO2they exhibits the lowest ratio; water has better thermal properties than helium, but thermal approach at PC is higher than in BNK, so their ratios are close. Finally, LDIV and HDIV work with helium and large thermal approach so their ratios are the highest. In [2] a sizing study of a S-CO2 power cycle for a helium cooled (with low temperature divertor) fusion reactor is given. The ratios of heat transfer rates to volumes in recuperators(229 m3for 1757 MW at LTR and 369 m3for 3326 MW at HTR) are similar with the ones resulting at present paper (taking into account they use the exact zigzag channel distribution of PCHE). However, they employ a shell and tube heat exchanger for the blanket heat source, requiring 4213 m3for 3000 MW. This entails to 4948 m3for all heat exchangers against 1696 m3at present paper. So, the selection of PCHE for all the heat exchangers (except for the LM)generates a large reduction in total volume, related with the costof the components [2].