The nuclear desalination based on the high temperature gas-cooled reactor (HTGR) with gas turbomachinery and multi-effect distillation (MED) has been drawing attention, because it can utilize waste heat for desalination. In this paper, research objectives are as follows: (a) proposing an optimal design of HTGR + MED systems and (b) performance and cost analysis for the HTGR + MED system. In the first step, the KAIST coupling scheme was proposed. It uses printed circuit heat exchangers (PCHE) instead of conventional heat exchangers without any intermediate loop and has the independent structure between MED plants and heat sink In the second step, the KAIST version of DEEP (K-DEEP) code was developed for more practical cost and performance analysis of the KAIST HTGR + MED system. The desalination performance and cost analysis with the K-DEEP code were performed for the Gas Turbine-Modular Helium cooled Reactor (GT-MHR) + MED system. The maximum desalted water production capacity increases by 258% compared to the production capacity using the previous coupling scheme. The desalted water cost could be reduced by 9.0%. Finally, from the comparison of various nuclear MED desalination systems we confirmed the potential of the KAIST HTGR + MED system that may be one of the best desalination options in mass production of desalted water. (C) 2012 Elsevier B.V. All rights reserved.