One of the potential undesired processes in the heat transport system of the GEN IV Supercritical Water Cooled Reactor (SCWR) concept may be the formation of nanosize particles from ions present in the feed water or released in the coolant by corrosion products. large-scale molecular dynamics simulations are being employed to investigate the nucleation and growth of salt nanoparticles in water over wide range of supercritical states. The particle nucleation rate in supercritical water appears to be on the order of 10(28) cm(-3) s(-1), with critical nuclei having an amorphous structure. A molecular mechanism for possible hydrolysis reaction at supercritical conditions is examined. (C) 2011 Elsevier B.V. All rights reserved.