are u asking for the enthalpy change for converting 500g of saturated steam at 100 celcius to solid ice at its triple point?
I am quoting values from "Thermodynamics and Transport Properties of Fluids" by GFC Rogers and YR Mayhew.
using interpolation from T=99.6-102.3C
hg = (100-99.6)/(102.3-99.6)*(2680-2675)+2675=2675,74kJ/kg
heat released = 1/2 hg = 1337.87kJ