Description of need
Vacuum pumps are the most critical gap in the fuel cycle for fusion energy.
The vacuum pumps in Nuclear fusion power plants need to be tritium-compatible. Tritium destroys all the seals, bellows, oils, lubrications, and other organic components found in pumps. After a few months, they turn to “putty” under the effect of tritium. This is true for all pumps except cryopumps. As a result, pumps employed in the fuel cycle may need to be replaced every 6-12 months. In addition to the replacement cost, the operational handling and exposure of the operator becomes problematic. The problem is there isn’t a pull for pump suppliers to do R&D around this! (Even the fission industry uses pumps for move moderators around, but the contamination is low.) There other pump challenges, most of which are concept-specific. For example, CFS has to deal with tritiated fluoride in its molten salt circulation pumps, in addition to the usual radioactive decay from tritium. Concepts that employ a lithium-lead blanket suffer from a similar problem.
Two pathways:
- Tritium-tolerant polymeric materials that fit into existing pump designs (see HyPOR - A tritium-compatible oil-based vacuum pump for fusion)
- Adapt pump designs to not need tritium-tolerant materials in the first place (see Metal foil pumps for direct internal recycling in fusion reactors).
Problem severity (1-10)
6
Who has this need
Fusion companies! Mentioned by both CFS and Tokamak Energy
Total addressable market (TAM)
Unknown
Solutions today, and their shortcomings
- Traditional vacuum pumps. Tritium destroys all the seals, bellows, oils, lubrications, and other organic components found in pumps. After a few months, they turn to “putty” under the effect of tritium. As a result, pumps employed in the fuel cycle may need to be replaced every 6-12 months. In addition to the replacement cost, the operational handling and exposure of the operator becomes problematic.
- Liquid Helium Cryopumps. Extremely inefficient and difficult to scale.
- Mercury diffusion pumps. Extreme environmental concerns. Costly disposable and maintenance.
- Metal foil pumps for direct internal recycling in fusion reactors. Low TRL and not a complete solution: still requires mercury pumps.
Potentially relevant capabilities
- HyPOR - A tritium-compatible oil-based vacuum pump for fusion
- Marathon Fusion and Metal foil pumps for direct internal recycling in fusion reactors
References
- 2023-05-02 Fusion Technology Roadmap Workshop at EPRI
- Don O. Coffin; A tritium‐compatible high‐vacuum pumping system. Journal of Vacuum Science and Technology 1 April 1982; 20 (4): 1126–1131. https://doi.org/10.1116/1.571586