Production of “artificial star fuel”
Lithium is used in the production of tritium, either in its liquid form, as a metal (lead lithium), molten salt (FLiBe) or in the form of lithium-based ceramics (lithium silicate, lithium titanate or a combination of both). A prototype fusion reactor such as DEMO requires a one-time input of nearly the entire annual production of beryllium (roughly 400 tons), in addition to some 150 tons of lithium ceramics, which involves a cost-intensive process of enriching the lithium with the lithium 6 isotope. Indeed, the fuel costs for DEMO could exceed the cost of building the reactor (several billion euros).
Fortunately, the material can be reused. ITER plans to test this approach. This will require roughly one ton of beryllium and 500 kg of highly enriched lithium for the concepts of several countries, with a price tag in the tens of millions euros. In the first half of this century, several fusion experiments around the world will be entering the critical phase (see graphic on p. 1: ITER starting in 2025) and will each require several kilos of tritium, which is very rare. Currently tritium gas can only be produced with the help of nuclear fission – a practice that is being phased out, in Germany at least, for political reasons. Clearly, greater attention must be paid to the question of where fusion reactors will get their “fuel”. This is an increasingly urgent issue – an area where effort and focus must be intensified immediately.