Pioro, I.Zirn, U.Duffey, R.Naidin, M.Mokry, S.Gospodinov, Ye.Baig, F.2014-12-102014-12-102008Poiro, I, Zirn, U, Duffey, R, Naidin, M, Mokry, S, Gospodinov, Ye & Baig, F 2008, Supercritical water-cooled nuclear reactors: thermodynamic-cycles options, Paper presented to the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July 2008.9781868546916http://hdl.handle.net/2263/42900Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.Currently there are a number of Generation IV SuperCritical Water-cooled nuclear Reactor (SCWR) concepts under development worldwide. The main objectives for developing and utilizing SCWRs are: 1) Increase gross thermal efficiency of current Nuclear Power Plants (NPPs) from 33 – 35% to approximately 45 – 50%, and 2) Decrease the capital and operational costs and, in doing so, decrease electrical-energy costs (~$1000 US/kW or even less). SCW NPPs will have much higher operating parameters compared to current NPPs (i.e., pressures of about 25 MPa and outlet temperatures up to 625°C). Additionally, SCWRs will have a simplified flow circuit in which steam generators, steam dryers, steam separators, etc. will be eliminated. Furthermore, SCWRs operating at higher temperatures can facilitate an economical co-generation of hydrogen through thermo-chemical cycles (particularly, the copper-chlorine cycle) or direct high-temperature electrolysis. To decrease significantly the development costs of a SCW NPP, to increase its reliability, and to achieve similar high thermal efficiencies as the advanced fossil steam cycles it should be determined whether SCW NPPs can be designed with a steam-cycle arrangement that closely matches that of mature SuperCritical (SC) fossil power plants (including their SC turbine technology). The state-of-the-art SC steam cycles in fossil power plants are designed with a single-steam reheat and regenerative feedwater heating and reach thermal steamcycle efficiencies up to 54% (i.e., net plant efficiencies of up to 43% on a Higher Heating Value (HHV) Basis). Therefore, simplified no-reheat, single-reheat, and double-reheat cycles without heat regeneration and a singlereheat cycle with heat regeneration based on the expected steam parameters of future SCW NPPs were analyzed in terms of their thermal efficiencies. On this basis, several conceptual steam-cycle arrangements of pressure-tube SCWRs, their corresponding T–s diagrams and steam-cycle thermal efficiencies (based on constant isentropic turbine and polytropic pump efficiencies) are presented in this paper.9 pagesPDFenUniversity of PretoriaSupercritical water cooled nuclear reactorsThermodynamic cycles optionsSCWRNuclear power plantsNPPSingle steam reheat and regenerative feedwater heatingPresentation