A model for the expansion phase of a neutron star atmosphere during strong x‐ray bursts is presented. General relativistic hydrodynamical and radiative transfer equations are integrated from the star surface outwards, taking into account for helium burning in the dense, inner shells. The role of Compton heating in placing a lower limit on the mass loss rate for the existence of stationary, supersonic winds is analyzed. Comparison of our results with observational data of 4U/MXB 1820‐30 provides an estimate of both the spectral hardening and the accretion rate in this source. ©1994 American Institute of Physics.