THE LOGIC BEHIND THICK, LIQUID-WALLED, FUSION CONCEPTS

It may be possible to surround the region where fusion reactions are t aking place with a neutronically thick liquid blanket which has penetr ations that allow only a few tenths of a percent of the neutrons to le ak out. Even these neutrons can be attenuated by adding an accurately placed liquid or solid near the target to shadow-shield the beam ports from line-of-sight neutrons. The logic of such designs is discussed a nd their evolution is described with examples applied to both magnetic and inertial fusion (HYLIFE-II). These designs with liquid protection are self-healing when exposed to pulsed loading, and have a number of advantages over the usual designs with solid first walls. For example , the liquid-protected solid components will last the life of the plan t, and therefore the capacity factor is estimated to be approximately 10% higher than for the non-liquid-walled blankets, because no blanket replacement shutdowns are required. The component replacement, operat ions, and maintenance costs might be half the usual value because no b lanket change-out costs or accompanying facilities are required. These combined savings might lower the cost of electricity by 20%. Nuclear- grade construction should not be needed, largely because the liquid at tenuates neutrons and results in less activation of materials. Upon de commissioning, the reactor materials should qualify for disposal by sh allow burial even when constructed of ordinary 304 stainless steel. Th e need for a high-intensity 14-MeV neutron test facility to develop fi rst-wall materials is avoided or greatly reduced, saving billions of d evelopment dollars. Flowing molten Li, the molten salt Flibe (Li2BeF4) , and molten Li17Pb83 have been considered. An advantage of molten sal t is that it will not burn and has a low tritium solubility and theref ore low tritium inventory.