This paper presents the methodology of techno-economic analysis for a nuclear unit operating in partial cogeneration mode and its application for the case study: a nuclear power plant planned in Poland. The research objectives were: to propose EPR, AP1000 and ESBWR nuclear condensing-extraction turbine systems modifications required for operation in cogeneration, to determine optimal heat production and heat transport line (HTL) parameters, to evaluate the technological feasibility of proposed solutions, to analyze profitability and competitiveness of the system versus coal-fired technologies. To adapt nuclear turbine to operation in partial cogeneration mode, the steam must be extracted from low-pressure (LP) section of the turbine and crossover pipe connecting high-pressure (HP) or intermediate-pressure (IP) section with LP section. Thermodynamic analysis proved that the operation of nuclear power plant at peak thermal load up to 250 MW neither requires to change primary cycle arrangements of considered nuclear units nor thermal capacities of nuclear reactors. Total annual costs of nuclear power plant operating in partial cogeneration were the lowest of all considered heat and power options, with all types of reactors, for the emission allowance price of 27 EOM CO2-eq. The specific cost of heat from nuclear cogeneration option was 10.3-12.7 EUR/GJ. (C) 2017 Elsevier Ltd. All rights reserved.