Nuclear Design of Heliotron Fusion Reactor Blankets

Abstract

A study is made of the nuclear characteristics of blanket designs intended for a helio-tron fusion reactor that employs an l=2 helical heliotron field and no toroidal coils. The blankets in front of the superconducting magnet (shielding blankets) are utilized for neu-tron shielding, and the other blanket regions (breeding blankets) for tritium breeding. A number of notable features inherent in this blanket concept are revealed : The stipulated tritium breeding ratio could be attained in the breeding blanket by utilizing lithium lead (Li₇Pb₂) as breeding material and helium as coolant, with a breeding zone thickness of 1 m. The shielding blanket should pose more difficult problems in satisfying the adopted design criteria : Holding the total blanket thickness to within the stipulated limit of 1 m would necessitate the incorporation of expensive material (e.g., W or Ta) in the blanket. The final choice between (a) thus enhancing the attenuating power of the material and (b) relaxing the limitation on blanket thickness will call for careful consideration from both system economics and technological aspects.