In　this　paper,　an　optimized　rectangular　corrugated　tube　is　used　for　the　super-critical　water　reactor　(SCWR)　cooling,　numerically.　Al2O3,　CuO,　Fe3O4　and　TiO2　nanoparticles　in　different　shapes　(spherical,　brick,　platelet　and　cylindrical)　are　considered　as　additives　to　SCW　for　cooling　purposes,　and　it　is　tried　to　introduce　the　most　suitable　cases　from　the　maximum　heat　transfer　view　point.　Piecewise　temperature-dependent　properties　are　considered　for　the　SCW　and　different　correlations　such　as　Brinkman　and　Pak　equations　were　examined　for　nanofluid　properties.　The　governing　equation　are　solved　based　on　control　volume　method　(CVM)　software,　where　the　SCW　properties　are　introduced　to　it　by　a　user　defined　function　(UDF).　As　the　main　outcome,　Pak　and　Cho　correlation　had　the　best　fitted　curves　with　other　presented　functions.　Also,　the　corrugated　tube　filled　by　spherical　alumina-SCW　had　the　best　performance　for　SCWR　cooling.　©　2021　THE　AUTHORS