Conceptual designs of PHTS, ESS and PCS for DEMO BoP with helium cooled BB concept

Abstract

The state of EU DEMO Balance of Plant as for the end of 2016 is described in this paper. Starting with 6 outboard and 3 inboard cooling loops, the thermal energy of the helium is transferred by an intermediate heat exchanger to the solar salt, which transports it out of the tokamak building to the energy storage system, which is actually an industrial 2-tanks design. Heat is transferred from solar salt to the feedwater in the steam generator where it boils and becomes superheated before entering the steam turbine. The steam turbine design follows state-of-the-art concept, but it is not finally optimized, since further DEMO BoP design changes still cannot be excluded. The other 3 usable heat sources (two from divertor and one from vacuum vessel) are used to heat-up the feedwater on the return line to the steam generator, thus contributing to the efficient utilization of heat produced during DEMO operation. Taking into account pulse/dwell times of 2.0/0.5 h, DEMO can operate permanently under ∼80% power thus allowing flexible and continuous plant operation. EBSILON® results are presented for steady-state conditions including both pulsed and dwell time periods.