LIBRA project: first tritium breeding results
Remi Delaporte-Mathurin, Nikola Goles, Colin Dunn, Emily Edwards, Samuele Meschini, Stefano Segantin, Sara Ferry, Ethan Peterson, Dennis Whyte, Edward Lamere, Kevin Woller and LIBRA collaborators
Tritium Focus Group, 28th November 2023
The tritium issue
\mathrm{D} + \mathrm{T} \rightarrow \mathrm{He} + \mathrm{n}
800 \ \text{MWth} \approx 10^{20} \ \text{reactions/s} \approx 100 \ \text{kg/year}
Cost: $30,000 per gram
Half-life: 12 years
\mathrm{T} \rightarrow \mathrm{He} + \mathrm{e}^-
☢
\mathrm{n} + ^6\mathrm{Li} \rightarrow \mathrm{T} + \mathrm{He} + 4.8 \ \mathrm{MeV}
\mathrm{n} + ^7\mathrm{Li} \rightarrow \mathrm{T} + \mathrm{He} + \mathrm{n} - 2.5 \ \mathrm{MeV}
\mathrm{TBR} = \mathrm{\frac{tritium \ produced}{tritium \ consumed}} > 1
❓How ❓
Lithium is used to breed tritium
\mathrm{D} + \mathrm{T} \rightarrow \mathrm{He} + \mathrm{n}
\mathrm{n} + ^6\mathrm{Li} \rightarrow \mathrm{T} + \mathrm{He} + 4.8 \ \mathrm{MeV}
\mathrm{n} + ^7\mathrm{Li} \rightarrow \mathrm{T} + \mathrm{He} + \mathrm{n} - 2.5 \ \mathrm{MeV}
⚛️Breeding tritium
🛡️Shield from neutrons
🔥Extract heat
Liquid Immersion Blanket
FLiBe
LIBRA: a demonstration of the LIB
What is the smallest blanket that can demonstrate a TBR of 1?
LIBRA
Liquid Immersion Blanket tritium Robust Accountancy
Objectives
🎯T self-sufficiency with DT neutrons
🎯Experience with molten salt handling
🎯Tritium extraction from molten salts
500L FLiBe
14 MeV neutron source
Inconel
double wall
Li + n → T + He
Neutron multiplier
The LIBRA experiment
Tritium transport
Transport mechanisms:
- Diffusion
- Advection
Release pathways:
- Release gas/liquid interface
- Permeation through walls
The LIBRA experiment
The LIBRA experiment
He
Tritium detection
The actual design is a bit more complex
LIBRA was designed to achieve TBR ≈ 1
\mathrm{TBR} = \mathrm{\frac{T \ produced}{T \ consumed}}
= \mathrm{\frac{T \ produced}{neutron \ produced}}
Neutronics simulations
Let's start smaller
- 14 MeV neutron generator \( 10^{10} \) n/s
- 500 L of FLiBe
→ Never done at MIT ⚠️
The BABY programme
V \frac{d c_\mathrm{salt}}{dt} = S - \textcolor{#ff7f0e}{Q_\mathrm{wall}} - \textcolor{#2a7eb8}{Q_\mathrm{top}}
Q_i = A_i \ k_i \ (c_\mathrm{salt} - c_\mathrm{external}) \\ \approx A_i \ k_i \ c_\mathrm{salt}
S = \mathrm{TBR} \cdot \Gamma_n
100 mL
ClLiF salt
Top release
Wall release
A simple 0D model is used to simulate BABY
= source - losses
inventory evolution
\(k\) mass transport coefficient
\(A\) surface area
neutron rate
Inconel 625
- 2 x 12 h irradiation
- \( \mathrm{TBR} \approx 3 \times 10^{-4} \)
- \( \Gamma_n \approx 4 \times 10^8 \) n/s (fitted)
- Mass transport coeffs. \( k_i \) (fitted)
100 mL
CLiF salt
Top release
Wall release
THIS is what we can measure!
Salt T inventory
T fluxes
Cumulative release
Salt crucible and two DT neutron sources
Tritium collection system
Temperature control
The BABY experiment breeds tritium at a smaller scale
HT, T2 → HTO
#1
#2
#3
#4
HTO, TF
HT, T2
Furnace
Tritium collection and accountancy
→ then analysed with Liquid Scintillation Counting
HTO, TF
HT, T2
15 Bq of tritium have been bred in total
Collected tritium
1 Bq = 10\(^{-15}\) mole of T
Collection effiency 99.8%
Model
Water is changed
Measurements agree with model
Cumulative tritium production agrees with model
Next experiments will provide information on the wall permeation
Cumulative tritium release (Bq)
- Still preliminary
- Change in dynamics to be explained:
- Unsteady neutron source?
- Change in mass transfer?
Cumulative tritium release (Bq)
2nd run showed comparable results
Next steps
- Improve repeatability
- Improve neutron detection and source characterisation
- FESTIM transport model (advection, tritium diffusion...)
- Increase volume of salt
- Switch to FLiBe
- Upgrade to LIBRA
100 mL
1 L
100 L
500 L
BABY
LIBRA
1L of salt
Top release gas sweep
Outer-vessel for capturing permeated tritium
Thank you!
Any question?
remidm@mit.edu
LIBRA project: first tritium breeding results (TFG talk)
By Remi Delaporte-Mathurin
