The paper gives the basic results of experimental investigation of boiling heat transfer in heat-absorbing devices of the ITER thermonuclear reactor, which are subjected to one-side heating. The experimental data on heat transfer at nucleate and film boiling and on critical heat fluxes are obtained in the following range of parameters of water flow: pressure p = 0.7-2.0 MPa, mass flux G = 340-25 000 kg/(m(2) s), and water temperature at the inlet T-in = 20-60 degrees C. A twisted tape is inserted in the circular channel in order to form swirling flow of water. The investigations are performed for tapes with different values of flow swirl coefficient, as well for test sections without a tape. Appropriate calculation formulas are derived, which reliably generalize the experimental data. (C) 2010 Elsevier Ltd. All rights reserved.