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Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 2 of 11
Safety Considerations Associated with FLiBe as an Advanced Breeder-Coolant for Fusion
Tritium Breeding Blankets
C.K. DORN (Kyoto Fusioneering America Ltd., Washington, USA) et al.
Safety Considerations Associated with FLiBe as an
Advanced Breeder-Coolant for Fusion Tritium
Breeding Blankets
Christopher DORN1, Paul BARRON2, Colin BAUS2,3,
Gerald DEGREEF2, Reuben HOLMES2, Takashi INO2, Satoshi KONISHI2,3, Keisuke MUKAI2,3,
Richard PEARSON3,4, Masato TABUCHI2, Bibake UPPAL1, and Juro YAGI3
1Kyoto Fusioneering America, Seattle, Washington, USA
2Kyoto Fusioneering Japan, Tokyo, Japan
3Kyoto University, Kyoto, Japan
4Kyoto Fusioneering UK, Reading, UK
Kyoto Fusioneering (KF), a private fusion technology company based in Japan, is exploring the use of
FLiBe (a lithium fluoride and beryllium fluoride eutectic mixture) molten salt as a promising breeder-
coolant for tritium breeding in fusion reactors. FLiBe has many attractive features, such as: high
neutron multiplication, excellent tritium breeding properties, low tritium solubility, limited
interaction with the strong magnetic fields present in a magnetic fusion reactor, and the ability for
operation at relatively low pressures.
However, FLiBe and its associated technologies are at relatively low technology readiness levels and
its use also raises several safety concerns that need to be addressed before it can be deployed in
experimental - and, ultimately, commercial - fusion reactors. In collaboration with Kyoto University,
KF is currently working with lab-scale quantities of FLiBe in a benchtop loop to develop our
experience and capabilities, marking the start of the FLiBe-oriented arm of our overall tritium
breeding research and development programme in the coming years (other breeder-coolants under
exploration are lithium-lead and pure lithium). This work provides an overview of the identified
safety issues associated with the use of FLiBe.
In a FLiBe breeding blanket, tritium will be produced by the interaction of neutrons with the lithium.
This results in the production of tritium fluoride (TF), which is highly reactive and corrosive to the
structural and functional materials, as well as components. The occurrence of corrosion comes with
a risk of releasing materials to the environment, which could have serious safety consequences from
both a conventional and radiological point of view.
Additionally, a fusion reactor must breed its own fuel, so any tritium produced in the form of TF must
also be separated out from the coolant to be injected back into the fusion reactor as fuel. TF is difficult
to handle and transport due to its high reactivity and mobility, and thus specialized equipment and
facilities are required for handling. It is thus desirable to remove TF, and strategies to remove TF
using Be and Li in redox reactions are being investigated by KF.
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 3 of 11
The corrosion behavior of FLiBe is worsened by the presence of impurities contained with the
mixture, which can be introduced either from the raw material of LiF and BeF2 before mixing, or from
corrosion during operation, meaning purification processes are desirable when operating a FLiBe
coolant loop. These processes involve the use of H2 and HF gas, both of which come with their own
safety considerations.
Known FLiBe-compatible materials are limited, and nickel-based alloys known to have good
compatibility produce large quantities of undesirable radioactive products under neutron
irradiation. Finding suitable materials is thus also driven by safety considerations.
KF is exploring whether FLiBe has promise as a breeding blanket material, and is sharply focused on
identifying and resolving safety concerns. Proper handling and containment measures should be
incorporated into the design at the earliest stages, to mitigate risks associated with its use. Here, the
challenges, as well as KF’s programme to understand and find solutions, are presented.
Corresponding Author:
Mr. Chris DORN
Technical & Business Advisor
c.dorn@kyotofusioneering.com
Kyoto Fusioneering America Ltd.
600 Stewart Street, Suites 300 & 400
Seattle, Washington 98101
U.S.A.
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 4 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 5 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 6 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 7 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 8 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 9 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 10 of 11
Excerpted from: Minutes of the Beryllium Health & Safety Committee (BHSC) 2023 Spring Meeting
9-10 May 2023 – Livermore, California, U.S.A.
_____________________________________________________________________________________
Page 11 of 11