Molten Salt and Ingredients in Tranquility
Executive Summary
Molten salt (FLiBe + thorium fluoride) is the MSR fuel/coolant. Life cycle: Sourcing → Mixing → Operation →
Waste. Rules mirror nuclear materials; risks low in lunar vacuum. This white paper covers details.
Composition and Life Cycle
Ingredients: FLiBe (LiF 66%, BeF2 34%; coolant/moderator) + ThF4 (fuel) + UF4
(starter). Total ~500 kg salt/reactor.
Sourcing: Li/Be from Earth (abundant); thorium as above.
Life Cycle: Mixed Earth-side; circulates in reactor (no corrosion in vacuum); fission
products accumulate; salt vitrified/buried at end (5-10 years).
Rules: IAEA transport standards (A2 classification for salt); UN OST for
space (no contamination).
Methods, Risks, Mitigation
Methods: Salt loaded sealed; online monitoring for composition.
Risks: Salt solidification (if cooled; mitigate with heaters); toxicity (Be toxic; handled
robotically). Low lunar risks (no leaks to environment).
Costs: $1-2M/reactor (ingredients); maintenance $5M/year
(sampling/swaps).
Open Questions: Salt recycling on Moon? Beryllium sourcing scalability?
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December 31, 2025
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