Reducing the Peak-to-Average-Power-Ratio in Fusion Blankets

Abstract

Breeding blankets with integrated first wall are one of the most critical components of nuclear fusion reactors. Blankets breeding zones are characterized by steep nuclear heating gradients due to the exothermic nuclear reaction 6Li(n, )T and the high intensity neutron flux in the proximity of the first wall. Non-uniformity in nuclear heating can generate sharp temperature gradients that deeply affect material properties. This conceptual study explores an original way to flatten nuclear heating profiles by proposing a blanket characterized by layers of different 6Li enrichment in the breeder region while maximizing Tritium Breeding Ratio (TBR) and power generation. Two types of fusion blanket are studied: (1) Helium Cooled Ceramic Reflector (HCCR) and (2) Dual Coolant Lead Lithium (DCLL). For HCCR, it is found in the optimal design case, that the power peak-to-average can be reduced by 47.85%, 42.45% and 54.13% in the front, middle and back channel respectively when compared to the reference design. On the other side, we found that this method of profile flattening is not appealing for DCLL, under the geometrical configuration and material selection in this particular blanket design, since most of nuclear heating is caused by photon heat deposition.