Stand-off blankets are ridiculous, and it’s comical that anyone thinks they are the optimal path to fusion power. It’s high time we embrace compact, contact-blanket designs — the kind that touch (or nearly touch) the reaction zone. A contact blanket uses only a tiny fraction of the material (orders of magnitude less), so there’s no need to strip-mine the Earth or deplete it of rare elements. For example, a contact blanket one meter thick requires about 4.19 cubic meters of material, whereas a stand-off blanket positioned ten meters out needs around 1,386 cubic meters — over 300 times as much material.
FLiBe is several orders of magnitude better at preventing neutron leakage than pure lithium. For example, a natural lithium blanket 1.5 meters thick would still allow 30% of its neutrons to escape, compared to just 0.001 (0.1%) escaping from a 2:1 (LiF):(BeF2) = @0.2843% Li blanket.
The plot (above), based on 7.59% ^6Li (natural lithium), shows leakage per source neutron.
The plot (below), based on 100% ^6Li, shows pure Li6 blocks more neutrons from escaping.
Assuming we stick to unenriched lithium (7.59% Li6), a one meter thick blanket would have the same TBR = 1.2, whether it is made of pure lithium or a 2(LiF):(BeF2) mixture of flibe.
The plot (above) is based on 7.59% ^6Li (natural lithium)
The plot (below) is based on 100% ^6Li
Instead of a blanket that’s far away from the action, contact-blanket designs place the blanket right up against the fusion zone — snuggling it like a boa constrictor. The result? You end up needing far less blanket material to do the same (or even better) job, and this approach doesn’t require cornering the world’s beryllium market.