Viability of the ¹¹B(p,α) 2α Cycle

We have evaluated the energetics of the proton-¹¹boron advanced fuel fusion cycle and find that the enhancement of reactivity obtained from non-thermal mechanisms is significantly less than the enhancement required for ignition or high gain operation. Based on a detailed calculation of synchrotron radiation losses, at least 135% enhancement of the reactivity is needed for ignition. The direct and induced radioactivity associated with the cycle, while being orders of magnitude lower than that of D-T, is not negligible and requires serious attention in the design. Thus, we conclude that, using our present physics knowledge, the p-¹¹B cycle is not viable for commercial fusion power.