Tritium Systems for Clean Energy: from betavoltaics to fusion power

From betavoltaic batteries to nuclear fusion, tritium has been proposed as the fuel source for multiple clean energy technologies. Although many beta-emitting isotopes exist, tritium is considered ideal in betavoltaic applications for several reasons: 1) it is a “pure” beta emitter (i.e., no gamma emission during tritium decay), 2) the beta particle is not energetic enough to damage semiconductor elements, 3) it has a moderately long half-life, and 4) it is readily available. Unfortunately, the widespread application of tritium-powered betavoltaics is limited, in part, by their low power output. The first half of this talk will provide an overview of work focused on increasing the power output of betavoltaic devices by increasing the flux of beta particles to the energy conversion device through the use of low-Z structured solid tritide films.

Tritium production and separation in a lithium-bearing breeding blanket is one of the key challenges facing fusion power. While the high affinity of lithium towards hydrogen isotopes reduces tritium losses due to permeation, it also leads to difficulties in recovering tritium from lithium tritide (LiT) formed during breeding. The direct LiT electrolysis process has been proposed as an option for tritium removal from liquid metal systems (e.g., pure Li, PbLi eutectic). This technique uses advanced solid lithium-conducting electrolytes to reduce the complexity and footprint of tritium extraction. Though there is currently a huge volume of work on lithium-conducting ceramics for use in battery applications, very little research has been performed on these materials in environments that would be relevant to a fusion reactor blanket. The second half of this talk will give an overview of lithium‑conducting ceramics tailored for use in a molten lithium environment.