Abstract

The possibility of developing Controlled Nuclear Fusion as a source of clean, carbon-free energy is the subject of intense debate and research activity since the 1950s. Several technologies for Fusion Reactors have been proposed among which the Tokamak (using toroidal plasma magnetic confinement) seems to be most promising. Recent efforts to develop new, high critical temperature superconducting (HTS) magnets can lead to retire one of the major drawbacks of a Fusion Power Plants, namely the large size due to the limited performance of conventional low-temperature superconductors in generating high magnetic fields. The development of compact reactors, such as the ARC project (lead by CFS and MIT), reduces costs but results in higher radiation levels and significantly higher power densities in the fusion blanket. The ARC project is targeting a new replaceable Reactor Blanket concept, based on the use of Molten Salts as shielding, tritium-breeding and cooling material. A collaboration between CFS, MIT and Eni is developing an integrated validation plan to fill the knowledge gaps and retire the technological risks of this endeavor. The roadmap to develop the tools required for the Blanket design is here described, that opens the way for fruitful synergistic collaborations with different industry and technology sectors.

Introduction

Magnetically confined nuclear fusion is one of the most promising innovative technologies for future production of heat and electric energy compatible with the goal of zero carbon emissions. In a future commercial Magnetic Fusion Plant the fusion materials, deuterium (2H) and tritium (3H) ions, will be confined in a Vacuum Vessel (VV) by powerful magnetic fields in a toroidal (doughnut-shaped) configuration at highest temperatures. The ions will collide and fuse to produce helium (3.8 MeV 4He, or a-particle) and energetic fast neutrons (14.1 MeV). Some of the a-particles will be kept confined in the VV to stabilize the energy and temperature of the reaction; the neutrons will spontaneously escape the confining field and diffuse away to be captured outside the VV. The plant component where the capture processes takes place is the so-called Reactor Blanket. The Blanket surrounds the VV and provides for the following key functions: (i) convert the kinetic energy of neutrons into thermal energy; (ii) convey thermal energy to the Heat Exchange System; (iii) breed tritium, the fusion fuel isotope that is not naturally available due to its relatively short (12.3 years half-life) decay time to helium 3He; (iv) cool the VV down to operational temperatures, and (v) shield the rest of the plant (outside the VV) from excess radiation.

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