Development and application of an alternative modelling approach for the thermo-mechanical analysis of a DEMO water-cooled lithium lead breeding blanket segment

•An alternative procedure to obtain a realistic thermal field for the central outboard blanket (COB) segment of the DEMO WCLL has been set-up and investigated.•A set of polynomial functions of the radial and toroidal variables has been obtained to reproduce the thermal field calculated in the COB equatorial region.•A comparison of the calculated and interpolated thermal field and of the corresponding secondary stress fields has been carried out.•To assess the applicability of the interpolation procedure to coarser mesh, a mesh independence study has been performed.•The polynomial functions have been applied to the whole COB segment to assess its thermomechanical response.