[en] This report considers the choice of parameters for a Reversed Field Pinch reactor with a net electrical output of 600 MW. The design assumes pulsed operation without refuelling during the burn, ignition by ohmic heating alone and the use of resistive magnetic field windings. Burn calculations are described, showing that operation at low plasma temperature with controlled energy loss is required to obtain adequate energy multiplication, and indicating the restrictions necessary to obtain ignition by ohmic heating. A choice of free parameters is made to minimise the capital cost of a complete generating unit including reactor, generators and energy storage system, and the sensitivity of the cost to the initial assumptions is analysed. The optimisation leads to a reactor design of 1.75 m first wall radius, with an energy multiplication factor Q of 6.9. (author)