Nuclear design and assessments of helical-axis advanced stellarator with dual-coolant lithium-lead breeding blanket: adaptation from DEMO tokamak reactor.

Abstract

As possible long-term alternative to a tokamak fusion power plant, the stellarator concept offers salient physics features (no external current drive, no risk of plasma disruptions, low recirculating power, among others) which could be offset by the more complex configurations and challenging maintenance schemes. Very little in the way of conceptual design studies has been performed compared to tokamaks and enhancement of engineering aspects should follow. With the recent start of operation of Wendelstein 7-X, the Helical-Axis Advanced Stellarator (HELIAS) line has raised again interest among the scientific and technologic EUROfusion Programme. The main aim at present is showing that stellarators (particularly helical axis stellarators) are viable as potential fusion reactors. To follow on the conceptualization of a mature HELIAS power reactor, different engineering and technological aspects must be studied, improved and solved. To this end, starting from a very preliminary reactor design called “HELIAS 5-B” (5-field-period) with a fusion power of 3000 MW, a neutronic model has been developed and analysed introducing in the baseline the relevant components of Breeding Blankets (BB). The large experience achieved at CIEMAT in BB designs for DEMO tokamak has been exploited, adapting the Dual Coolant Lithium-Lead Breeding Blanket (DCLL BB) design elaborated in the frame of the WPBB Programme of EUROfusion/PPPT, to the HELIAS configuration. Preliminary neutronic assessments have been performed focusing on tritium production, power density distributions and damage/shielding responses as nuclear heating, neutron fluence, dpa and helium production. Particle transport calculations have been performed with MCNP5v1.6 Monte Carlo code.