[en] HOTPIN computes the detailed steady state temperature distribution within and around the pins of a fuel cluster which is cooled by radiation and convection from the pin surfaces. Pins are divided into radial and azimuthal (r, 0) meshes. Internal conduction between mesh areas is treated by a finite difference technique. Radiation between mesh elements at the surfaces of the pins is represented by a matrix of view factors defining the radiation emitted by each surface element which is eventually absorbed by each other element after any reflections. Surface convective heat transfer is represented by a uniform heat transfer coefficient around each pin. (author)