Abstract
Nuclear heat IS process is consisted of HI and H2SO4 decomposition-recycling reactions and expected to be hydrogen mass production plant with couple of HTGR. Conceptual design study on ceramic evaporator of concentrated sulphuric acid for IS process has been carried out in Japan atomic research institute. The paper reports the results of erosion test of ceramics under high temperature sulphuric acid and conceptual design of full scale evaporator of suiphuric acid in nuclear heat IS plant.