In　order　to　improve　the　evaluation　accuracy　of　wetness　losses,　a　quantitative　evaluation　program　of　wetness　losses　was　developed　using　the　Fortran　language　from　the　calculation　results　of　wet　steam　flow　with　non-equilibrium　condensation.　A　three-dimensional　(3D)　simulation　of　the　wet　steam　flow　with　non-equilibrium　condensation　in　a　multi-stage　turbine　was　performed　to　obtain　the　aerodynamic　parameters　and　3D　distribution　of　the　fine　droplets.　Then　the　3D　results　were　circumferentially　averaged　to　obtain　the　flow　field　in　the　meridian　plane,　and　the　parameters　of　the　flow　field　were　used　to　quantitatively　evaluate　the　wetness　losses.　The　wetness　losses　in　the　low　pressure　(LP)　cylinder　of　a　nuclear　steam　turbine　were　calculated.　The　results　show　that　the　thermodynamic　loss　is　mainly　generated　in　the　intermediate　and　last　stages　where　the　non-equilibrium　condensation　occurs.　The　droplet　drag　loss　has　a　greater　proportion　in　the　last　stage,　and　lower　proportion　in　other　stages.　The　brake　loss　is　the　most　important　component　of　the　wetness　losses,　and　it　increases　stage　by　stage.　The　collected　water　loss　and　the　centrifugal　loss　have　small　proportions　in　the　total　losses.　The　total　wetness　losses　in　the　LP　cylinder　under　consideration　account　for　3.1%　of　the　total　output　power　of　the　LP　cylinder,　less　than　3.9%　predicted　by　the　Baumann　rule.