Liquid Immersion Blanket: Robust Accountancy (LIBRA)

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OPEN 2021
Cambridge, Massachusetts
Project Term:
04/11/2022 - 04/10/2024

Critical Need:

Fusion power using deuterium-tritium (D-T) fuel must achieve unprecedented tritium-breeding ratios (TBR) to enable rapid fusion deployment and play a role in grid decarbonization. FLiBe based liquid-immersion-blanket (LIB) science , a simple molten salt made from a mixture of lithium fluoride and beryllium fluoride, remains at basic principles from a lack of experimental data and capabilities in the breeding material under flux of neutrons from D-T fusion reactions.

Project Innovation + Advantages:

The Massachusetts Institute of Technology’s Plasma Science and Fusion Center and Idaho National Laboratory, with its Safety and Tritium Applied Research Facility, propose a critical-path tritium-breeding experiment for LIB technology. The technological development for LIBs requires high temperatures, hazardous material handling and access to D-T fusion neutron sources. The Liquid Immersion Blanket: Robust Accountancy (LIBRA) experiment will investigate tritium-breeding capabilities under these extreme conditions. It will examine a simple molten-FLiBe-salt approach to tritium-breeding for fusion power plants and show this is possible with 70% lower-cost LIB technology than state-of-the-art breeding blankets.

Potential Impact:

The LIBRA team will demonstrate unprecedented tritium-breeding ratios possible with 70% lower cost LIB technology.


LIBRA offers the energy market a representative T-breeding test stand that provides T containment and real-time accountancy.


Successful LIBRA development would dramatically accelerate tritium-breeding and the deployment rate of fusion power.


LIBRA's success would enable a LIB prototype demonstration and create a new technology-to-market pathway to tritium-breeding for fusion power plants at substantially lower cost than conventional blankets.


ARPA-E Program Director:
Dr. Ahmed Diallo
Project Contact:
Kevin Woller
Press and General Inquiries Email:
Project Contact Email:


Idaho National Laboratory

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