Future Energy and Fusion Power Plants
Jan Coenen
Jan.Coenen@gauss-fusion.com
KIT International School on Fusion Technologies
May 7th 2025
© 2025 Gauss Fusion GmbH - confidential
Aim of this talk
To use the properties of fusion, and expectations of future energy markets, to see how fusion might
play a role
• The energy challenge
• Fusion resource availability
• Fusion research
• Costs and investment
• Conclusions
The information is derived from detailed technical work in power plant design studies, and
socio-economic studies. Only a summary is given here.
© 2025 Gauss Fusion GmbH - confidential
The challenge
How can the world continue to develop, and poor countries continue to grow, without excessive
cost – whether financial, environmental, or other?
For all countries to reach this
point, world energy use would
need to double with today’s
population, or increase 4-fold with
GOAL?
the 11bn expected in 2100.
Even if all developed countries
came down to this point the
factors would be 1.8 today, 2.1 in
2030.
© 2025 Gauss Fusion GmbH - confidential
Source: https://www.gapminder.org/
Energy use/capita – more
recent data hard to obtain!
3
Examples of excessive cost
London smog (pollution event)
• Thousands can die in a single
pollution episode.
Source: Wilkins
Death
800
SO2Concentration
1
0.8
600
0.6
400
0.4
200
0.2
0
0
1
3
5
7
9
SO2-Concentration
[ppm]
but overcome by regulation
1000
Number of deaths
• Cost associated with industrialisation
11 13 15 17
December 1952
© 2025 Gauss Fusion GmbH - confidential
4
Example of excessive cost
• Developing country biomass use generates indoor particulates.
• Up to 2.5 million premature deaths each year, mostly women and
children.
• Cost associated with insufficient or inappropriate development.
Source: WHO. Picture: Practical Action
© 2025 Gauss Fusion GmbH - confidential
5
Costs of climate change
Costs to communities and
economies from changes in
weather patterns, externalised
from energy generation costs.
Erftstadt, Germany, 2021
Photograph: Rhein-Erft-Kreis Handout/EPA
© 2025 Gauss Fusion GmbH - confidential
6
Many good reasons to pursue clean
energy!
• Climate change
• Particulate emissions and other pollution
• Health
• Quality of life
• Costs of „dirty air and water“
• Growing demand for energy…
© 2025 Gauss Fusion GmbH - confidential
7
Growth in energy use is enormous
Two characteristic regions of the world, near
saturated energy demand and dramatically growing
energy demand.
Recently just the growth in Chinese consumption has
equally total German consumption.
Source: EIA, https://www.eia.gov/
© 2025 Gauss Fusion GmbH - confidential
8
Energy consumption
• More than 80% of global energy use is
supplied by fossil fuels. In business as
usual scenarios, most world energy will still
be supplied by coal by 2100. Source: BP
© 2025 Gauss Fusion GmbH - confidential
9
Increasing energy demand, reducing emissions
• World energy growth predicted to continue but CO2
should plateau and decline to keep atmospheric
content below e.g. 550 ppm. Decoupling energy and
CO2 will require dramatic changes in energy systems.
Source: IPCC
• Outline solutions are available! Combination of
renewables, energy storage, and baseload, but
elements of all of these require development and
deployment – and acceptance by society.
© 2025 Gauss Fusion GmbH - confidential
10
The shape of future energy markets
• Using real seasonal data, investigating amount of energy
Source: Romanelli 2016
storage required for different levels of baseload power and
total solar generation.
fpv = 60%
• Few TWh storage can make a big difference, but Pbase,crit
increases for increasing fpv.
• Available pumped storage in Italy ~0.25 TWh
• Significant investment in grid infrastructure required if
fintermittent is high.
• Often correlation across large scales for European weather
systems for wind and solar.
• Role for 20%+ supply from low-carbon baseload in mixed
grid
© 2025 Gauss Fusion GmbH - confidential
Source: VGB Powertech 2019
11
Large volatility in energy markets
EU ETS carbon price €/tonne CO2
Factor of 3 in six months
World oil price
Factor of 10 in 10 years
Target for a future energy price is very uncertain
© 2025 Gauss Fusion GmbH - confidential
12
The role of fusion in a future energy system
• Fusion is a baseload technology
• Reliable, steady generation
• Can “trickle charge” storage
• Capital intensive, CoE is stable once built
• Relatively small amounts of baseload can dramatically reduce storage and installed capacity
requirements in a mostly-intermittent renewable system
• Lowers overall system cost even if LCoE or spot price is higher than renewables
• Safer/cleaner than fission, the main low-carbon rival for this role
• Fusion emerges in models with carbon constraints, if it is cost competitive
See Integration of fusion power in future decarbonized power systems, Chiara Bustreo
© 2025 Gauss Fusion GmbH - confidential
13
Market characteristics of fusion
Fusion resources: main fuels are deuterium and lithium
© 2025 Gauss Fusion GmbH - confidential
14
How much fuel is available?
• Deuterium 1/6700 atoms of hydrogen.
• 1 litre of water contains 0.033 g of deuterium.
• Energy equivalent of 10 GJ or 280 litres of oil.
• Enough deuterium for billions of years of energy supply.
• Tritium, bred from lithium.
• Lithium in 3 laptop batteries enough for lifetime personal energy needs (~240,000 kWh).
• Land-based lithium reserves sufficient for thousands of years.
• Fuel reserves are enormous and not an issue.
© 2025 Gauss Fusion GmbH - confidential
15
Ultimate fuel resource for different energy systems
Large resource in coal, fission breeder, and fusion.
Solar provides a large resource as well.
Although fusion fuels appear essentially unlimited, we
should take care not to be too dependent on other
scarce resources. Examples often quoted are tantalum
(an alloying element in low activation steels), beryllium,
and helium (mostly obtained from gas wells).
On the other hand, materials procurement is a small
fraction of the cost of fusion electricity so large
increases in the price of raw materials could be
tolerated.
© 2025 Gauss Fusion GmbH - confidential
Source: WEC, BP, USGS, WNA
16
Other materials
Development in e.g. China has also seen large price rises in steel, concrete, etc. All electricity
generation costs inflated.
Nominal construction cost indices. IHS-CERA PCCI
tracks coal, natural gas, nuclear, and wind power
plants from 2000-2014. HWI tracks steam-generating
electric technologies, including coal, natural gas, and
nuclear power plants from 1980-2014. HWI trend
extends back to 1970. U.S. GDP deflator from U.S.
Bureau of Economic Analysis, 1980-2000.
Source: Muratori et al, Renewable and Sustainable
Energy Reviews, 77 (2017)
© 2025 Gauss Fusion GmbH - confidential
17
Projected costs of fusion
Large uncertainty inherent in
projections. Include projected fuel price
increase but no carbon tax. Wind is
near-term technology but no standby or
storage costs.
Source: “Projected costs of generating electricity”,
IEA, 1998 update, PPCS
Fusion has to outcompete fission,
economics of a plant (high capital cost,
low operational costs) are similar.
Seems unlikely to hope that fusion can
be much cheaper, especially in the
near term.
© 2025 Gauss Fusion GmbH - confidential
18
Technological learning reduces costs
Source: Solarbuzz
https://www.nrel.gov/news/program/2021/documenting-a-decade-of-costdeclines-for-pv-systems.html
Expect this in fusion too, but to what extent?
Depends on modularisation, standardisation, rate
of build, and regulatory environment
https://www.construction-physics.com/p/why-are-nuclear-power-construction
© 2025 Gauss Fusion GmbH - confidential
19
Costs and investment
Costs reduce through R&D and scale
GW-scale devices projected to be in few $/W range
Power which would be produced if non-DT devices
were to use DT
Source: Ward
© 2025 Gauss Fusion GmbH - confidential
20
Fusion power plants
© 2025 Gauss Fusion GmbH - confidential
21
What is fusion?
• Fusion is the process that produces energy in the core of the
Sun and other stars
• Temperature in the core of the sun is ~15 million ºC, pressure
is 300 billion atmospheres.
• Hydrogen fuses to give deuterium, then helium (and energy).
First step is very, very slow.
• Power density in core is ~300 Wm-3 (similar to a large
compost heap). Would need 107 m3 for a reasonable power
station!
© 2025 Gauss Fusion GmbH - confidential
22
D-T fusion
Fortunately other fusion reactions are much faster.
3
2
4
1
1𝐷 +1 𝑇 →2 𝐻𝑒(3.5MeV) +0 𝑛(14.1MeV)
© 2025 Gauss Fusion GmbH - confidential
p-p 10-45
In temperature range 10<T<20 keV, reactivity ~T2
Care is needed at higher temperatures!
23
How are high temperatures achieved?
House
JET
Heating power (W)
10,000
10,000,000
Insulation
Glass fibre wool
Magnetic field
Thickness (m)
0.1
1.0
Thermal conductivity (W m-1 K-1)
0.040
0.001
Temperature (K)
300
100,000,000
© 2025 Gauss Fusion GmbH - confidential
24
Plasma pressure
• To achieve sufficient power density the plasma density must be “large”.
• A typical target value is 1020 m-3 (electron density) which is approximately
105 times lower than atmospheric particle density.
• However the temperature is ~106 times higher than ambient, so the
required pressure is only a few atmospheres.
• This is not a “high pressure” system. (Although many engineering systems
see high pressures.)
© 2025 Gauss Fusion GmbH - confidential
25
Fusion power gain
Q = fusion power / input power
Pfus = n2/4 × reactivity × volume × Efus
In temperature range 10<T<20 keV,
reactivity ~ 4 ×107 T2 (T in J)
© 2025 Gauss Fusion GmbH - confidential
26
Fusion power gain
Power to maintain plasma temperature
= 3𝑛𝑇𝑉/𝜏𝐸
(τE is the energy confinement time = E/P)
𝑛2 𝑇 2 𝜏𝐸 𝑛𝑇𝜏𝐸
𝑄=
=
𝑛𝑇105
105
the fusion triple product.
If pressure is expressed in atmospheres Q = nTτE !
Ignition – where alpha power (=Pfus/5) is sufficient to sustain temperature requires
𝑛𝑇𝜏𝐸 ≈ 5 atmosphere seconds
This is only approximate. Now that we are close it is not accurate enough to use over-simplified
arguments.
© 2025 Gauss Fusion GmbH - confidential
27
Minimum Q for a power plant
Steady-state tokamak
operation requires high
current drive power!
Efficiency product multiplies heating and current drive (HCD) wall plug efficiency and plant electrical conversion
efficiency, e.g. wall plug efficiency 50% with 40% thermal conversion efficiency gives product of 0.2. Q must be
above 12 in that case.
Emult is the energy multiplication due to nuclear reactions in the blanket.
© 2025 Gauss Fusion GmbH - confidential
28
Plasma requirements for high energy gain
• High temperature to obtain high fusion cross-section (T>10 keV,
routine in JET and similar devices)
Resistive coil limit
• High density to produce high power: n>1020 m-3.
→ pressure in range of a few atmospheres
• Good thermal insulation so that the plasma temperature can be
sustained without high input powers. Otherwise no net energy
gain.
• These values achieved in current machines, just not usually
simultaneously and not for long times
Fig. 6(B): The fusion triple product, nTE, in atm s
versus the duration of the high-performance phase
[s] for fully (or quasi-) non-inductive regimes only
X. Litaudon et al 2024 Nucl. Fusion 64 015001
© 2025 Gauss Fusion GmbH - confidential
29
Major progress over decades
Huge strides in physics, engineering, and technology.
JET: 16 MW of fusion power ~ equal to input power.
21 MJ of fusion energy in one pulse.
Currently building ITER – next generation, GW scale
tokamak.
Scaling laws that fit data from existing tokamaks give
confidence that ITER/power plants will achieve
desired performance.
© 2025 Gauss Fusion GmbH - confidential
30
JET
Formerly
• Currently the world’s best magnetic fusion research facility. Only operating facility capable of D-T fusion
(DTE2 achieved new records in 2021 and 2022). Resistive (copper) TF coils limit pulse length.
© 2025 Gauss Fusion GmbH - confidential
31
ITER
Aim is to demonstrate integrated physics and
engineering on the scale of a power station (500 MW
fusion power, superconducting magnets, test blanket
modules).
Europe, Japan, Russia, USA, China, South Korea, India
(>3 Bn people)
Construction in Cadarache, France
Key ITER technologies fabricated and tested by
industry.
© 2025 Gauss Fusion GmbH - confidential
32
JET and ITER versus power plants
R0 = 3 m
R0 = 6 m
JET
(now)
EU
16 MW
Q≈1
© 2025 Gauss Fusion GmbH - confidential
ITER
(~2027-2035)
EU, Japan, USA, Russia,
China, S. Korea, India
500 MW
Pfus ≈ Pelec, in
Power plant
(2040 onwards?)
2-3000 MW
Pelec,net >> 0
R0 = 9 m
33
Tokamak vs Stellarator
Transformer coil
Modular field coil
Poloidal field coil
Toroidal field coil
"Twisted" plasma shape
Toroidal magnetic field lines
External Coils and current induced in plasma
produce magnetic fields
Overview
TRL
Type of coils
Operation
Plasma
High
Simple coils
Limited discharge time
Instabilities due to plasma current
Complex twisted coils produce fields
Medium
Complex coils
Continuous operation
Stable plasma
Technical Study
Non-technical Study
Favorable
Mixed
Construction
complexity
Construction
cost
HighPerformance
Operation
Long Pulse
operation
Levelized cost
of Energy
Remote
maintenance
Competition
Collaboration &
workforce
Public support
IP Generation
Unfavorable
Stellarator
Tokamak
© 2025 Gauss Fusion GmbH - confidential
34
Characteristics of a fusion power plant
• What follows uses tokamak studies as the basis for analysis.
• Many of the technology issues would be similar for a stellarator.
• There is significant overlap also with technology for inertial fusion – although there are
significant differences too, of course.
© 2025 Gauss Fusion GmbH - confidential
35
Key components
Coils
Blanket
Divertor
Ports for maintenance,
diagnostics, heating,
etc.
Outside the vessel is the ordinary world, inside is the fusion world with
specific materials and structures
© 2025 Gauss Fusion GmbH - confidential
36
TECHNOLOGY ASPECTS
Tritium Breeding Blanket is a key component to run an FPP ensuring fuel
self-sufficiency
Technology concept
• Self-sufficiency in tritium production is critical for fusion power plants
due to its scarcity in nature and essential role in the fusion reaction
• Breeding blanket, a technology involving lithium materials that produce
tritium when hit by neutrons, is a solution to one of the most significant
challenges in the fusion industry - the short supply of fuel
Technology readiness level
• At its current technology readiness level of c.3, TBB must significantly
advance to reach level 6 or 7 before a fusion power plant can be
constructed
• With sufficient R&D, it will take around 10 years to ensure this
technology works
TBB has currently a low TRL
Current
machines
ITER
FPP
Gauss Fusion approach
Protect magnets & vacuum vessel from
neutron and gamma radiation
• Gauss Fusion introduces an industrial perspective to the development
of the TBB & fuel cycle, accelerating its advancement to an operationsready level
Produce the tritium necessary for
continued fusion reactions
Convert neutron energy into heat and
evacuate it to generate a cycle capable of
supplying electricity
• The company can significantly contribute to the development process
by leveraging connections with industrial companies for extensive,
integrated testing of this technology
Gauss Fusion aims to significantly enhance the TBB & fuel cycle development's efficiency and value by incorporating an industrial viewpoint right from the initial
stages
© 2025 Gauss Fusion GmbH - confidential
Source: CEA, KIT, ITER, IAEA
37
TRITIUM FUEL CYCLE AND BREEDER BLANKET
Potential Choice : Helium Cooled Pebble Bed – for early deployment
Technology rationale & gaps
• Lifetime 3-5 years with high availability
• Direct path to production unit
• RAFM steel as structural Material
• Helium as purge gas and coolant (80bar)
• Tungsten as amour material
• Li ceramic pebbles (60% enriched)
• Beryllium multiplier
Known gaps
• TBR > 1.1
• Design of components / Materials data
• Blanket will be ILW (Type B)
• Coolant loop design
• BB incorporates shielding
• Breeder material availability
• Temperature 400 C to 550 C
• Testing capabilities do not yet exist
Hernández, F.A., et al. Journal of Nuclear Engineering
4, 565–601. https://doi.org/10.3390/jne4030037
© 2025 Gauss Fusion GmbH - confidential
38
TRITIUM FUEL CYCLE AND BREEDER BLANKET
Design challenges en route to deployment
Stellarator shape
• Modular breeding blanket to cover various shapes
• Shielding to be adapted to meet lifetime requirements on VV / coils
• Consideration towards maintenance to be incorporated
Materials for TBB
• Breeding blanket materials will evolve during staged approach
• Testing of blanket modules to be performed in parallel to engineering
design
• Neutron source required for both materials / functional tests
© 2025 Gauss Fusion GmbH - confidential
39
Plasma exhaust
The trough in the base of the
tokamak is called the
divertor. It is the exhaust
system where power and
particles are extracted.
Probably the most
challenging part of ITER.
Power levels of 10-20 MW m-2 will fall here. ELMs can
provide power pulses.
Interactions with the wall can generate UFOs like
shooting stars as small particles of dust fall into the
plasma.
© 2025 Gauss Fusion GmbH - confidential
In a QI stellarator, magnetic islands
are created at the plasma edge, and
the divertor „cuts“ this island
W7-X
40
FUEL CYCLE
Plasma exhaust must be recirculated
Architecture Development – Work in Progress
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
He4
He4
H
H
D
D
T
T
T
Imp
Imp
TI m p
TI m p
Ne
Ne
HTO
HTO
H2O
H2O
He3
MONITOR
He3
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
He4
He4
H
H
D
D
T
T
T
He3
Imp
Imp
TI m p
TI m p
Ne
Ne
HTO
HTO
H2O
H2O
He3
MONITOR
T
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
TI m p
Imp
He4
He4
H
H
D
D
T
T
T
H2O
HTO
Ne
TI m p
T
Imp
D
H
He4
He3
H2O
HTO
Ne
H
He4
He3
H2O
HTO
Ne
TI m p
He3
H2O
H2O
H2O
HTO
HTO
HTO
Ne
Ne
Ne
TI m p
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
H
Heating, Ventilation, and Air Conditioning
He4
Ne
Imp
H
He4
He3
H2O
HTO
Ne
TI m p
T
Imp
D
H
He4
He3
H2O
HTO
Ne
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
Imp
D
D
T
T
TI m p
Ne
D
H
He4
He3
H
He4
Imp
Imp
TI m p
Ne
Imp
TI m p
Ne
HTO
TI m p
Ne
HTO
H2O
Ne
HTO
H2O
He3
HTO
H2O
He3
He4
H2O
He3
He4
H
He3
H2O
Emergency
Air Detritiation System
H
Imp
T
D
He4
Imp
TI m p
D
TI m p
START UP
T
H
HTO
H2O
HTO
Ne
TI m p
D
Imp
T
T
Ne
Imp
TI m p
E-ADS
Imp
Imp
He3
MONITOR
Imp
Imp
Imp
HTO
Ne
TI m p
TI m p
TI m p
H2O
HTO
Ne
HTO
Ne
He3
H2O
TI m p
D
H2O
HTO
He4
He3
Imp
T
He3
H2O
H
He4
T
He4
He3
D
H
D
HVAC (TFC)
H
D
He3 Storage & Export
T
D
T
T
D
H
He4
He3
He3
T
He4
D
H
H
D
He4
T
TI m p
D
T
He4
TI m p
D
Imp
HSE
H
Ne
TI m p
HTO
Ne
H2O
HTO
D
Imp
He3
H2O
He4
He3
H
He4
D
H
T
T
D
Imp
T
D
Imp
TI m p
T
T
TI m p
He3
HTO
Ne
Imp
Imp
TI m p
TI m p
Ne
He3
Imp
HTO
He4
TI m p
H2O
H
Ne
He3
D
H2O
He4
He4
HTO
HTO
H
H
H2O
H2O
D
D
He3
He3
MONITOR
T
T
MONITOR
T
T
He3
H
He4
He3
He4
HTO
HTO
H2O
H2O
H
PTS
Ne
Imp
Imp
TI m p
TI m p
Ne
Pure Tritium Storage
D
H
He4
He3
H2O
HTO
Ne
He4
He3
H2O
HTO
Ne
TI m p
T
D
H
He4
He3
H2O
HTO
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
T
D
H
He4
Imp
T
T
HTO
HTO
H2O
H2O
He3
He3
He4
He4
H
H
D
D
T
HTO
Ne
TI m p
H
He4
He3
H2O
HTO
Ne
TI m p
T
T
D
D
H
TI m p
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
H2O
HTO
Ne
TI m p
Imp
He3
H2O
HTO
Ne
Imp
TI m p
TI m p
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He4
MONITOR
TI m p
Imp
He3
Imp
He4
TI m p
H
Ne
Ne
D
HTO
HTO
H2O
T
He3
H
H2O
D
He3
HTO
HTO
H2O
H2O
He3
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
Imp
Imp
T
TI m p
D
T
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
Ne
TI m p
Imp
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
HTO
Ne
TI m p
Imp
He4
He4
He4
He3
He3
H2O
H2O
HTO
HTO
Ne
Ne
TI m p
T
T
D
H
H
TI m p
Imp
T
He3
D
Imp
D
He4
He3
H2O
HTO
Ne
TI m p
TI m p
TI m p
TI m p
Ne
Ne
Ne
HTO
HTO
HTO
H2O
H2O
H2O
Imp
Imp
He3
He3
He3
TI m p
TI m p
He4
He4
He4
Ne
H
H
H
ISS
Isotope Separation System
H
HTO
D
D
H2O
T
T
D
GDI
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
He3
H2O
Imp
WDS
T
He4
Water Detritiation System
D
D
H
H
He4
He4
He3
He3
Waste
Buildings
H2O
H2O
HTO
HTO
Ne
Ne
TI m p
TI m p
Imp
Imp
Imp
Imp
TI m p
H
TI m p
TI m p
Ne
D
Ne
Ne
HTO
T
HTO
HTO
H2O
Imp
H2O
H2O
He3
TI m p
He3
He3
He4
Ne
He4
He4
H
HTO
H
H
D
H2O
D
D
T
He3
T
T
Gas Distribution Injection
T
Imp
Imp
Imp
Imp
Imp
Ne
HTO
Imp
H
D
T
HTO
TI m p
Imp
TI m p
D
He4
He4
He4
H2O
Ne
Ne
H
H
H
H
Ne
HTO
HTO
He4
D
D
T
D
HTO
H2O
He3
T
T
PVT
Pressure Volume Temperature
T
He3
H2O
He3
Imp
Ne
TI m p
Imp
Imp
Imp
TI m p
TI m p
Ne
Ne
H2O
He4
Imp
TI m p
ESS
Emergency & Shutdown Storage
Imp
Ne
TI m p
H
TI m p
Ne
D
Imp
HTO
HTO
Ne
TI m p
Imp
H2O
HTO
He3
H2O
He4
He3
H
He4
D
H
T
HTO
Imp
TI m p
H2O
Ne
He3
HTO
He4
H2O
D
H
Imp
He3
T
T
He3
D
TI m p
He4
Imp
TI m p
T
Ne
H
T
HTO
He4
He3
T
Imp
He3
He4
He4
HTO
H2O
He3
Imp
TI m p
Ne
RESTART
VALIDATION
H
H
He4
D
H2O
He3
D
Ne
Imp
He3
He4
H
He4
Ne
He3
TI m p
H2O
Ne
HTO
HTO
Imp
H
He4
D
H
H
Imp
H2O
Ne
D
H
T
D
D
TI m p
He3
D
T
D
HTO
HTO
Ne
TI m p
T
Imp
He4
T
H
START UP
T
H2O
H2O
H
He4
He3
H2O
HTO
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
D
Stellarator
Building / Zone
T
He3
Imp
Imp
T
T
HVAC (STEL)
He4
TI m p
Imp
HPS
He 3 Purification System
T
Heating, Ventilation, and Air Conditioning
H
Heating, Ventilation, and Air Conditioning
Ne
TI m p
TI m p
TI m p
HTO
Ne
Imp
Imp
Ne
Ne
H2O
HTO
TI m p
TI m p
HTO
HTO
Tritium Purification System
Ne
Ne
H2O
H2O
H2O
HTO
HTO
H2O
H2O
He3
He3
He3
He3
He3
He4
He4
He4
He4
He4
H
H
He3
H
H
H
D
D
D
HVAC (WASTE)
He4
D
D
D
T
• Plasma exhaust includes D, T, H, He,
Ne, W…
T
T
Slight Tritium
into Atmosphere
via Chimney
that is Kick-ass
Imp
TPS
D
D
Imp
H
H2O
He4
He3
He3
He4
H2O
H
HTO
D
Ne
T
TI m p
Imp
TI m p
Imp
Ne
T
HTO
He4
H2O
H
He3
D
He4
T
H
T
Imp
D
Imp
TI m p
TIE
H
TI m p
D
T
H
T
D
Ne
STACK
Ne
T
T
T
Tritium Import Export
Imp
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
H
He4
He3
H2O
T
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
D
D
T
T
Imp
Imp
TI m p
TI m p
Ne
Ne
HTO
HTO
H2O
H2O
He3
He3
He4
He4
H
H
D
D
T
T
D
He4
H
HTO
HTO
H2O
H
H
He3
D
He4
He4
He4
He3
H
T
GDP
H2O
He4
He3
H2O
HTO
Ne
TI m p
Imp
Gas Distribution Pellets
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
He3
H
He4
He3
H2O
HTO
Ne
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
H2O
TI m p
Imp
He4
He3
H2O
HTO
Ne
TI m p
Imp
H
T
HTO
He3
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
HTO
H2O
He4
IRPR
Imp
GPS
H
Imp
H
Isotope Rebalencing and Protium Removal
TI m p
D
TI m p
D
He4
D
Imp
TI m p
He3
D
T
Ne
T
He3
He4
H
T
T
Ne
HTO
Pellet Injection System
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
TI m p
TI m p
Ne
Gas Puffing System
T
Imp
D
H
H2O
H
Imp
He3
H2O
HTO
Ne
Ne
TI m p
Imp
Imp
TI m p
TI m p
Ne
He4
Imp
HTO
H
TI m p
H2O
D
Ne
He3
T
HTO
He4
SPLITTER
HTO
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
HTO
Ne
TI m p
Imp
H2O
HTO
Ne
TI m p
Imp
D
D
T
He3
T
T
D
D
He3
H
HTO
HTO
H2O
H2O
He4
He4
H
PS-C
H
Pumping System - Cryostat
He4
Ne
He3
TI m p
TI m p
Ne
H2O
T
T
H
TI m p
He4
Ne
He3
HTO
He4
H2O
He3
He3
H2O
He4
HTO
H
Ne
D
He3
MONITOR
He3
D
T
H2O
T
T
He4
He4
H
H
Imp
Imp
D
D
TI m p
HTO
Ne
TI m p
HTO
Imp
H2O
T
He3
D
He4
H
H
He4
D
He3
T
H2O
Imp
TI m p
Ne
Ne
HTO
HTO
H2O
D
Imp
H2O
HTO
H2O
He3
H2O
He3
He4
He3
He4
H
He4
PIS
H
D
H
D
Imp
T
Ne
TI m p
TI m p
D
D
T
T
Ne
Ne
T
T
HTO
HTO
Imp
Imp
H2O
H2O
TI m p
TI m p
Ne
H
He3
D
Ne
T
Ne
• Must be “cleaned up” and re-injected
as efficiently as possible
T
TES
Tritium Extraction System
Imp
H2O
H2O
Imp
HTO
HTO
Ne
Ne
TI m p
TI m p
D
H
He4
He3
H2O
HTO
Ne
Imp
Imp
T
Imp
TI m p
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
D
H
HTO
H2O
He3
He4
ADS
Imp
TI m p
Ne
Air Detritiation System
T
Imp
Imp
D
D
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
He3
He3
T
T
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
D
D
Ne
T
HTO
HTO
D
D
H2O
H2O
T
T
He3
He3
He4
He4
Imp
Imp
H
H
TI m p
TI m p
Ne
Pumping System - Walls
T
HTO
HTO
H2O
H2O
He4
He4
H
PS-W
H
Rear
Surfaces
TI m p
TI m p
T
TBB Plasma
Ne
Ne
Service Vacuum System
T
Imp
TI m p
D
Ne
H
HTO
He4
H2O
He3
He3
H2O
He4
Ne
H
TI m p
D
Imp
Imp
TI m p
HTO
Ne
HTO
HTO
H2O
H2O
H2O
He3
He3
He3
He4
He4
He4
H
SVS
H
H
D
D
D
T
T
T
T
HTO
T
T
Ne
Imp
TI m p
TI m p
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Ne
TI m p
Ne
NST
H
EES
He4
He3
He3
HTO
HTO
Neon Storage Tanks
Ne
TI m p
Imp
T
D
H
He4
He3
Imp
Imp
D
H
He4
He3
T
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
HTO
Ne
Imp
TI m p
D
H
He4
He3
H2O
HTO
Ne
Imp
Imp
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
T
D
TI m p
Ne
HTO
H2O
He3
He4
H
MFP
Metal Foil Pump
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
He4
He3
H2O
HTO
Ne
TI m p
Imp
TI m p
Imp
Imp
T
D
H
T
D
H
He4
He3
H2O
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Ne
Imp
TI m p
TI m p
Imp
Ne
Imp
HTO
TI m p
H2O
Ne
He3
HTO
SPLITTER
He4
H2O
Imp
Imp
He3
TI m p
TI m p
VAC
PUMP
He4
Fuel Cycle Reactor Interface
H
H
Ne
Ne
D
D
HTO
HTO
T
T
H2O
H2O
Ne
He3
He3
HTO
He4
He4
H2O
FCRI
H
H
He3
D
Imp
Imp
TI m p
TI m p
Ne
Ne
D
He4
HTO
HTO
T
H
H2O
WDC
Water Divertor Cooling
Imp
D
He3
T
He4
T
H
T
TI m p
T
Ne
D
HTO
H
H2O
He4
He3
He3
He4
H2O
H
HTO
D
D
H2O
TI m p
HTO
TI m p
T
He3
Ne
Ne
Ne
H2O
TI m p
Imp
He4
HTO
He3
Imp
TI m p
HTO
He4
Ne
Water Detritiation Concentrator
Ne
H
H2O
H
H2O
HTO
H2O
D
He3
D
HTO
H2O
He3
T
He4
HTO
T
Imp
He3
He4
H2O
TI m p
TI m p
Imp
He4
T
T
H
He3
TI m p
Ne
Ne
Emergency & Shutdown Storage
TI m p
WDC
H
H
T
D
He4
HTO
H2O
H2O
Ne
D
D
WVS
T
H
T
Imp
HTO
T
T
Water Vessel Shielding
D
D
HTO
H
H2O
He4
He3
He3
He4
H2O
H
Ne
D
Imp
T
Imp
T
Ne
He3
D
T
Imp
TI m p
HTO
He4
He4
Ne
H2O
H
H
HTO
He3
D
D
H2O
He4
T
T
TI m p
TI m p
Imp
Ne
Imp
TI m p
HTO
Local Extraction Ventilation
Ne
H2O
H2O
He3
HTO
HTO
He3
He3
He4
Imp
H2O
He4
He4
H
H
H
H
D
D
D
T
• Minimise (and account) T inventory
T
D
TI m p
He3
Divertors
T
Ne
He4
T
Ne
HTO
TI m p
H2O
Imp
He3
He4
He4
He3
H
H2O
D
H
LEV
H
T
First
Wall
Imp
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
HTO
Ne
TI m p
Imp
T
T
Imp
Imp
TI m p
TI m p
Ne
Ne
HTO
HTO
H2O
H2O
He3
He3
He4
He4
H
H
D
D
T
IES
T
Imp
Imp
TI m p
TI m p
Ne
Ne
HTO
HTO
H2O
H2O
He3
He3
He4
He4
H
H
D
D
T
Impurity Extraction System
T
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
H
He4
Ne
TI m p
H2O
HTO
Ne
TI m p
Imp
Imp
D
D
HTO
H
HVAC (HOTCELL)
He4
T
He3
T
HTO
HTO
D
H2O
D
H
Imp
Imp
H2O
HTO
Ne
TI m p
T
Imp
D
He3
D
H
He4
He3
H2O
HTO
Ne
TI m p
H
Imp
Imp
He4
He3
H2O
HTO
Ne
Imp
TI m p
D
T
D
He4
H
SDS
TI m p
Imp
Imp
Ne
Solid Detritiation System
Imp
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
Imp
TI m p
T
D
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
T
T
D
D
H
H
Imp
He4
He4
He3
He3
HTO
Ne
TI m p
He4
Imp
H
TI m p
D
Ne
T
HTO
Imp
H2O
H2O
PRS
He3
Imp
HTO
HTO
H2O
TI m p
H
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
T
Imp
TI m p
HTO
He4
Ne
H2O
He3
HTO
He3
H2O
H2O
He4
HTO
He3
H
Ne
He4
D
TI m p
H
TI m p
TI m p
T
Imp
D
H-ADS
Hot-Cell Air Detritiation System
Ne
Ne
He3
TI m p
HTO
HTO
H2O
Ne
H2O
H2O
HTO
HTO
He3
He3
Ne
H2O
He4
Imp
He4
TI m p
He3
H
TI m p
H
Imp
He4
D
Ne
D
T
H
T
HTO
Imp
T
D
D
GDS-SCS
Gas Detritiation System
for
Secondary Containment Systems
H
T
H2O
TI m p
Imp
He4
Imp
He3
Ne
TI m p
He3
TI m p
HTO
Ne
H2O
Ne
He4
H2O
HTO
T
HTO
H
He3
H2O
D
H2O
D
He4
He3
H
He3
T
H
He4
He4
He4
D
H
He3
H
SCS
D
H2O
D
Secondary Containment Systems
HTO
TI m p
Ne
Ne
TI m p
HTO
Imp
H2O
T
Ne
Ne
Pebble Reprocessing System
T
T
D
D
He4
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
D
H
He4
He3
HTO
Ne
Imp
TI m p
HTO
Ne
Imp
HTO
Ne
TI m p
Imp
T
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
H
He4
TI m p
Imp
Imp
TI m p
He3
H2O
HTO
Ne
TI m p
Imp
He4
He3
H2O
HTO
Ne
TI m p
Imp
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
D
H
He4
He3
H2O
HTO
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
D
H
He4
He3
H2O
HTO
Ne
TI m p
He4
He3
H2O
HTO
Ne
TI m p
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
He4
H
D
T
H
H2O
HTO
Ne
TI m p
D
He4
He3
H2O
HTO
TI m p
H
D
Imp
Imp
D
Ne
Imp
He3
T
H
SCPS
TI m p
H2O
HTO
Ne
TI m p
Imp
GDS-APB
Gas Detritiation System
for
Active Permeation Barrier
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
HTO
T
H2O
Imp
Mechanical Power Plant
Buildings
Hot Cells &
Reprocessing
Building / Zone
D
D
T
T
He4
H
He3
HCS
Hot-Cell Containment Systems
He3
H
He4
He3
He4
HTO
HTO
H2O
H2O
H
PGS
Imp
Imp
TI m p
TI m p
Ne
Power Generation System
Ne
Ne
Ne
HTO
HTO
H2O
H
D
He4
Ne
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
T
He3
He3
He4
H2O
H
D
T
H
Secondary Coolant Purification System
T
D
D
T
D
Imp
T
SHTS
Secondary Heat Transfer System
T
TI m p
Imp
Ne
TI m p
HTO
Ne
Imp
Imp
HTO
TI m p
TI m p
H2O
Ne
Ne
He3
HTO
HTO
He4
H2O
H2O
H
He3
He3
D
He4
He4
T
T
H
H
Imp
D
D
TI m p
T
T
Ne
H2O
Imp
HTO
He3
TI m p
H2O
He4
Ne
He3
H
HTO
He4
D
H2O
H
APB
Active Permeation Barrier
T
He3
D
Imp
Imp
He4
T
TI m p
TI m p
H
SHL
Secondary Heat Loop
Ne
Ne
Imp
HTO
HTO
TI m p
H2O
H2O
Ne
He3
He3
HTO
He4
He4
H2O
H
H
He3
D
D
D
He4
T
T
T
H
Imp
T
D
H
He4
He3
TI m p
Imp
H2O
T
D
Imp
He3
T
T
TI m p
He4
PHTS
Primary Heat Transfer System
Ne
H
Imp
Imp
D
TI m p
TI m p
T
GDS-HCS
Gas Detritiation System
for
Hot-Cell Containment Systems
HTO
Ne
Imp
H2O
HTO
Ne
H2O
HTO
TI m p
H2O
He3
He3
H2O
Ne
He3
He4
He4
He3
HTO
He4
H
H
He4
Imp
H2O
H
D
D
H
TI m p
He3
D
T
T
D
Ne
He4
H2O
Imp
T
HTO
H
Imp
H2O
D
He3
H2O
He3
T
He4
He3
D
HTO
He4
T
Ne
H
HVAC (HTS)
H
H
T
Heating, Ventilation, and Air Conditioning
D
H2O
T
TI m p
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
Imp
Imp
TI m p
TI m p
Zeolite Regeneration System
Ne
Ne
Primary Coolant Purification System
Imp
Imp
T
TI m p
TI m p
Ne
TI m p
HTO
Ne
HTO
HTO
H2O
H2O
H2O
He3
He3
He3
ZRS
He4
He4
He4
H
H
H
D
D
D
T
T
T
Imp
Imp
Ne
Imp
HTO
TI m p
Imp
TI m p
H2O
Ne
TI m p
Ne
He3
HTO
He4
HTO
He3
T
He4
H2O
HTO
H2O
He4
T
PCPS
He3
He3
He4
H
T
H
He4
H2O
H
D
T
D
H
D
T
RHS
Remote Handling System
T
T
D
T
He3
T
Imp
TI m p
TI m p
Ne
FCRI Regeneration System
Ne
HTO
HTO
H2O
He4
Imp
He3
TI m p
He3
H
TI m p
He4
Ne
He4
D
Heating, Ventilation, and Air Conditioning
H2O
H
T
H
H2O
He4
He3
He3
He4
H2O
H
FRS
T
T
© 2025 Gauss Fusion GmbH - confidential
He3
T
D
T
D
Ne
• Complex, continuous process (ITER
and JET are batch-oriented)
D
T
T
D
H
He4
He3
H2O
HTO
Ne
TI m p
Imp
41
Superconducting magnets
• Reactor performance limited by magnet technology
(critical field, critical current, conductor heating).
• Superconductors also limited by manufacturing and
brittleness – need support structures.
20 m
• Must be shielded from radiation.
• Can be extremely large (manufacturing issues)
12 m
© 2025 Gauss Fusion GmbH - confidential
42
Stellarator coils
• „Modular“ coils (i.e. combined TF and PF) need to supply
plasma rotational transform
• Results in complex, hard to manufacture (and support)
shapes
• Must allow enough space for blanket/shielding between
plasma, VV, and coils
• Engineering effort required to simplify design and
assembly
© 2025 Gauss Fusion GmbH - confidential
43
Remote maintenance
All in-vessel systems will be contaminated by tritium and
radionuclides from neutron irradiation.
Maintenance must be carried out robotically, and
removed components stored in hot cells until recyclable.
Efficient operations to minimise downtime are vital to the
economics of the power plant.
EU-DEMO remote maintenance concept
© 2025 Gauss Fusion GmbH - confidential
Stellarator port/blanket segmentation concept
44
FUSION MATERIALS RESEARCH ESSENTIAL
Establish supply chain and know how
Making fusion sustainable
1
EUROFER supply chain & materials data
•
Supply chain for EUROFER is highly constrained
•
Start purchasing when choices are made
•
Allow for alternative steel options (Grade 91) for initial blanket after ALARA assessment
Lithium enrichment
Beryllium as multiplier material
2
•
GIGA would need ~300 t of Beryllium
Yearly production is on same level
•
Explore Pb as alternative
3
•
GIGA will need ~50-70 t of Enriched Lithium
~5000 t of Hg for ~10t/y production (ICOMAX)
•
Mercury production 1200 t per year
•
Exploration of new methods needed
Supply chains & R&D & environmental impact
Not just how we put it together, but what we make it out of.
Lowest swelling observed in body-centred cubic alloys (V alloys, ferritic steel). A key issue regarding BCC alloys is radiation
embrittlement. Also PFMs, HHF materials, tritium permeation barriers, rapid decay of waste…
Strong partnerships between industry, supply chain and research institutions are needed
© 2025 Gauss Fusion GmbH - confidential
45
EU power plant studies (PPCS, 2000s)
Looked at a range of power plants
Model A: water-cooled steel
Model B: Helium-cooled steel
Model C: Steel and SiC composite with He and LiPb coolant
Model D: SiC composite with LiPb coolant
Each developed in sufficient detail
that overall properties of safety,
waste, emissions, cost etc. could
be determined.
© 2025 Gauss Fusion GmbH - confidential
A, B, C: ~3000 MW fusion
D: ~2000 MW fusion
Full tritium cycle
1000 MW electricity
Steady-state
Maintenance: remote
handling optimized for high
availability
46
Potential harm from waste materials
Radiological hazard from fusion materials decays rapidly,
with a half-life of around 10 years. Real hazard depends
strongly on achievable impurity levels – this means
specific fusion material supply chains must be
developed.
Source: PPCS
Carbon-14 is produced naturally in the atmosphere by
cosmic ray bombardment of nitrogen.
Nitrogen in a fusion plant undergoes the same effect, but with
much larger fluxes
To keep C-14 production well below the natural level requires
nitrogen concentrations at or below 100 ppm.
This is true of some materials and not others, so choices can
be important
SS-316
OPSTAB
RAFM
© 2025 Gauss Fusion GmbH - confidential
600 ppm
3,000 ppm
<100 ppm
47
Tritium release
One of the main hazards in an accident.
Maximum possible release from an internal accident are few 10s of grammes.
Doses to local population are, in the worst case, too low for evacuation to be considered.
An external accident, e.g. enormous earthquake, could potentially release more but the
consequences of the event itself would be much more serious than any releases from the plant.
Bounding accident analysis, combines the worst outcome in each
area. Releases still small and doses to the public low.
Compared with approximately 4 mSv average background in EU
Source: PPCS, SEAFP
© 2025 Gauss Fusion GmbH - confidential
Model
Dose
A
1.2 mSv
B
18.1 mSv
48
Fusion costs
• Typical costs breakdown by system
• Costing studies also typically look at financing and project
management costs which can be 1/3 of total plant costs
• „Fuel/consumables costs“ (blanket, divertor) small fraction
of total
• Learning factors applied to fusion-specific components
© 2025 Gauss Fusion GmbH - confidential
49
Cost variation with key parameters
1
1
𝑐𝑜𝑒 ∝ 0.6 0.4 0.5 0.4 0.3
𝐴 𝑃𝑒 𝜂𝑡ℎ 𝛽𝑁 𝑁
technology
physics
coe is cost of electricity, A is
availability, ηth is conversion
efficiency, Pe unit size, βN
normalised β, N is normalised
density.
In one study (2000) we looked at the way that a number of key parameters affect the final cost of electricity.
Assumed Nb3Sn coils with conventional assumptions.
We could re-do this with a different parameter set, and calculate capital cost instead of cost of electricity. (This
has already done in a simplified analytic study.)
Caution – interactions become complex e.g. βN and H interact through I, B, n etc.
© 2025 Gauss Fusion GmbH - confidential
50
A FUSION POWER PLANT ISN’T JUST THE STELLARATOR
GIGA fusion power plant layout
Cooling Towers
Substation
Turbine
Building
Hot cell
Water
Treatment
Power supplies
Plasma
heating
systems
Offices
Stellarator
Building
Cryoplant
& Control
Tritium plant
Site access control
© 2025 Gauss Fusion GmbH - confidential
51
SITE SELECTION
Space, customers, logistics, regulation, and politics
Site selection activities need site requirements:
© 2025 Gauss Fusion GmbH - confidential
•
Logistics and hence max. component size
•
Regulation will always have local considerations and
choice of country fixes authority: early engagement
required and need to engage on design as it
proceeds, need to document design choices and
evaluation
•
Fusion regulation process cannot be fully specified
until there is an FPP design to test it against…
•
Safety principles and approach established early
52
SITE SELECTION
Space, customers, logistics, regulation, and politics
Each blue point is an area fulfilling
the filter criteria:
1
> 60 ha area
2
Electrical grid
3
Cooling
4
Urban areas “nearby”
Present estimate area: 1000 x 1260 m2
= 126 104 m2 = 126 ha
with
FPP core (1-5):
560x500 = 28 ha
Electricity:
700x500 = 35 ha
Grid (8):
700x300 = 21 ha
General use (14): 700x200 = 14 ha
Total:
100 ha
© 2025 Gauss Fusion GmbH - confidential
53
Conclusion
• Fusion requires a high temperature, around 100 million K.
• This is routinely achieved.
• To achieve high power gain the density must be sufficiently high and the
thermal insulation sufficiently good to reduce the required heating power.
• JET is around Q=1, ITER designed at Q=10, DEMO/FPP Q=20-40
• Fusion has a very large, widely distributed, fuel resource, enough for many
thousands of years of energy supply.
• Fusion power stations should have very good safety and environmental
properties. If made to work (with reasonable availability) they have the chance
to provide an economic source of energy.
© 2025 Gauss Fusion GmbH - confidential
54
Questions?
© 2025 Gauss Fusion GmbH - confidential
55
Coffee break
© 2025 Gauss Fusion GmbH - confidential
56
Basics of magnetic
confinement fusion and
fusion technology
© 2025 Gauss Fusion GmbH - confidential
57
A JET plasma lasts about 1 minute
Limited by heating of (resistive copper) magnets,
heating of inertially-cooled components.
© 2025 Gauss Fusion GmbH - confidential
58
What is a tokamak?
•
•
Leading current technology for (magnetic) fusion power
Derived from the Russian for toroidal magnetic chamber
from plasma current
1/
© 2025 Gauss Fusion GmbH - confidential
R toroidal field dependence
59
Why different magnetic field components?
A simplified description is that:
The poloidal field provides insulation (confinement)
The toroidal field provides stability
The additional vertical field provides equilibrium and shape
The additional radial field provides shape and stability
© 2025 Gauss Fusion GmbH - confidential
Plasma current
TF coils
PF coils
Plasma rotation,
profiles, heating
60
STELLARATOR HISTORY
Stellarators were one of the first magnetic confinement concepts
Inherently steady-state (no current drive, no transients)
•
Poor thermal particle orbits (neoclassical confinement)
•
Poor energetic particle orbits (alpha confinement)
Better Confinement
•
1
𝜈
𝜈
Banana
Plateau
PfirschSchlüter
Lyman Spitzer, Jr. standing next to the Model A
stellarator at Princeton.
More Reactor-like
© 2025 Gauss Fusion GmbH - confidential
61
THE STELLARATOR COMEBACK
Recently advances in theory are making stellarators attractive
•
Thermal particle confinement optimization (drift optimization) → Quasi-symmetries
•
Energetic particle confinement optimization
•
Turbulence optimization
Ions
Electrons
Normalized heat conduction in W7-X and LHD showing neoclassical optimization effect.
Beidler, C.D. et al., Nature 596 7871 (2021) 221.
© 2025 Gauss Fusion GmbH - confidential
62
STELLARATOR SHAPING
Shaping of magnetic flux surfaces defines the device physics
n=0
n=1
n=5
-4.02 MA
560 kA
0A
Eps_eff
= 0.002
Eps_eff = 0.00045
© 2025 Gauss Fusion GmbH - confidential
63
STELLARATOR PHYSICS
Optimization of the magnetic field shape is key
•
The magnetic coils determine the plasma shape
•
The plasma shape determines the plasma physics (geometric and magnetic field quantities)
•
Non-linear optimizers are used to design both plasma shapes and magnetic field coils
A stable quasi-isodynamic stellarator configuration (SQUID).
Goodman, A.G. et al., PRX Energy 3 2 (2024) 023010.
© 2025 Gauss Fusion GmbH - confidential
Coil centerlines for GIGA device with coilplasma distance.
64
Tokamak equilibrium
A current-carrying ring tends to expand under the
pressure of its own magnetic field.
I
In order to counteract the expansion force, an
external, vertical, magnetic field must be applied
F
𝐹 = 𝐼𝐵2𝜋𝑅
F
F
The plasma pressure, as well as the current,
applies an outward force.
Additional coils – vertical field coils – are
installed for this purpose.
F
I
© 2025 Gauss Fusion GmbH - confidential
65
Stability
A fusion plasma has almost no mass (0.01g in JET) but is subject to large
forces.
Instabilities can accelerate (grow) very fast.
Fortunately most gross instabilities involve moving the (locked in) magnetic flux
with the plasma and this is opposed by conducting structures so instabilities are
slowed down. As the plasma moves, currents are induced in the vessel
creating a magnetic field that pushes back on the plasma.
One key instability is the vertical instability.
Shaping the current ring, elongating it, makes it unstable to vertical
displacements.
Use coils above and below the plasma to pull on it and cause elongation.
Motion towards one coil leads to imbalance and instability.
Need fast (millisecond) feedback on RADIAL FIELD to stabilise.
© 2025 Gauss Fusion GmbH - confidential
66
Plasma stability
There are other possible instabilities, which are specific to plasmas as opposed to rigid current rings,
usually associated with plasma waves and resonances around the toroidal loop.
An example arises if we put too much current in the plasma loop, in which case the toroidal field is no
longer strong enough to suppress gross instabilities.
This can lead to a sudden loss of energy and can also couple to a loss of position control.
A resulting Vertical Displacement Event (VDE) is not good. The machine is operated so that it can
tolerate even the worst possible example.
In a VDE, the plasma can contact the vessel, driving further currents – known as halo currents – through
the vessel.
Instabilities due to pressure gradients in the edge can cause ELMs (edge localised modes) which dump
power into the divertor, like a grenade going off
© 2025 Gauss Fusion GmbH - confidential
67
Confinement / insulation
Magnetic fields cause charged particles to spiral around field lines.
Plasma particles are lost to the vessel walls only by relatively slow
diffusion across the field lines.
Only charged particles (D+, T+, He+…) are confined. Neutrons
escape and release energy.
A toroidal (ring shaped) device is a closed system intended to avoid
end losses.
© 2025 Gauss Fusion GmbH - confidential
68
Magnetic insulation
600 Larmor orbits to edge of JET
Time to escape by diffusion = collision time ×6002.
Collision time approx. 5 ms: confinement time ~6002 ×0.005 = 0.5 hrs.
Extremely high value.
A power of 10MW in a 100m2 device would give a central
temperature of 1011K, instead of 108K required for fusion.
Scaling with machine parameters
Confinement time ∝ a2B2T1/2/n
A larger machine with stronger magnetic field gives better confinement.
This level of confinement is not possible, even theoretically in a
tokamak. BUT WHY NOT?
© 2025 Gauss Fusion GmbH - confidential
69
Neoclassical effects
A toroidal device has extra flow of current and even different classes of particle
orbits. These give extra losses.
The pressure gradient is balanced by j×B force, but B varies substantially
across the plasma (1/R!), typically by a factor of 2.
This leads to additional currents and thermal losses.
Inboard
The magnetic field is stronger at smaller major radius, so particles
with low toroidal velocity are reflected. The increased orbit size
increases transport further. The existence of trapped particles is
very important.
Outboard
Inboard
|B|
Outboard
© 2025 Gauss Fusion GmbH - confidential
70
Trapped particles
Step size larger than Larmor orbit by factor of B/Bθ≈10, hence transport
approximately 100 times classical.
Only low parallel velocities are trapped so only a fraction of particles are trapped;
however the scattering between trapped and ‘passing’ occurs quickly.
In total, trapped particle transport (‘neoclassical’) ~50 times larger than classical.
This difference in trapped and passing particle confinement, and the scattering
between them, leads to a net imbalance in passing particle flows: the selfdriven “bootstrap” current.
Important for reducing current drive requirements (and hence recirculating and
exhaust powers) in future power plants.
© 2025 Gauss Fusion GmbH - confidential
71
Turbulent heat loss
In a real fluid there will be turbulence, as in water flowing
down a pipe.
Simple, laminar, calculations of flows are unlikely to be
correct and this turns out to be the case in tokamak
plasmas.
Turbulence may drive convective cells or increase the
effective collision frequency.
This leads to heat losses of around 10 times higher than
those predicted by simple theory.
This is often referred to as ‘anomalous transport’.
Simulation of turbulence in tokamak plasma
(plasma core is not simulated). (Source: Nathan
Howard, MIT)
© 2025 Gauss Fusion GmbH - confidential
72
H-mode
What is an H-mode?
At high power levels the thermal
insulation improves by forming
an edge “barrier”
Temperature
35
30
ELMy H-mode
The edge gradients can be so strong that
periodic relaxation instabilities occur – Edge
Localised Modes
T (keV)
25
20
L-mode
15
H-mode
10
5
0
0
This is an improvement on earlier performance (“Lmode”), we have also identified “advanced” modes
of operation.
© 2025 Gauss Fusion GmbH - confidential
0.2
0.4
0.6
0.8
1

73
ELMs
ELMs in MAST. Source: UK Atomic Energy Authority
© 2025 Gauss Fusion GmbH - confidential
74
Overall energy confinement
Simple classical theory would predict a level of thermal conductivity of
10-6 W m-1 K-1, 40,000 times lower than the insulation in a house.
Toroidal effects increase thermal conductivity by two orders to
approximately 400 times lower than a house.
Real experiments have higher thermal conductivity still, around 40
times lower than house insulation.
We can improve this through advanced modes of operation – but ITER
does not rely on these.
© 2025 Gauss Fusion GmbH - confidential
75
Plasma heating
Simply starting up a tokamak plasma and driving a current of ~3 MA (e.g. JET) raises the
temperature to around 3 keV or 30 million K (through resistive heating).
Maximum that can be achieved this way is ~3.3 keV; need >4.4 keV before alpha heating starts
overcoming radiation losses.
The main options beyond that are neutral beam injection (NBI) or radio frequency (RF) heating.
Both techniques work and have different strengths and weaknesses.
For a tokamak (and a stellarator, for MHD control purposes) we also want CURRENT DRIVE from
these systems
© 2025 Gauss Fusion GmbH - confidential
76
NBI
JET
NBI
injector
ITER high energy,
negative ion acceleration
NBI system.
© 2025 Gauss Fusion GmbH - confidential
77
RF heating
Because the particles in the plasma are charged they will interact with radio
waves, especially those that are at plasma resonant frequencies.
But for the same reason the propagation of radio waves in a plasma is very
complex.
With the different masses of ions and electrons there are a range of possibilities
for frequencies, interactive with ions (~50 MHz), electrons (~100 GHz) or (more
complex) at intermediate hybrid frequencies (~5 GHz).
These are usually called ICRH, ECRH, or LHCD – the latter usually considered as
a current drive rather than a heating scheme.
© 2025 Gauss Fusion GmbH - confidential
78
RF heating: ECRH
• Can be generated far from plasma and injected down a
mirroring waveguide (good for neutron shielding)
• ITER developing 170 GHz gyrotrons (6 T), suitable for FPP
• Higher frequency for higher fields only as concepts
© 2025 Gauss Fusion GmbH - confidential
79
RF heating: ICRH
• Reliable systems available
NBI beam duct
Limiters
LHCD antenna
ICH antennae
•
•
Divertor
Requires an antenna inside torus
Heats ions!
© 2025 Gauss Fusion GmbH - confidential
80
Pros and cons: plasma heating
NBI needs to generate ions, accelerate them to large energies, and re-neutralise
them. This tends to lead to large systems. At present high efficiency is hard to
achieve, especially at high energy.
RF systems tend to be more efficient in generation but can have difficulties
coupling waves to the plasma. For instance at ICRH frequencies, the waves can
only be injected by an antenna very close to the plasma otherwise little energy
gets in.
An enormous advantage of these systems is that they can also drive currents in
the plasma, allowing steady-state operation and control of the current profile for
improving stability, energy confinement, etc.
Ideally want delicate parts far from fusion plasma -> ECRH for FPP
© 2025 Gauss Fusion GmbH - confidential
81
Plasma currents
Plasma currents of many mega-amps are an important part of operating a large
tokamak.
Toroidal current supplies the plasma poloidal field which helps stabilise the
plasma.
At fusion temperatures the electrical resistivity is low, comparable to copper, so
(much) less than 1V is required to drive the current through transformer action.
However a transformer is intrinsically AC, so a steady-state (or DC) tokamak
relies on self-driven (bootstrap) currents and external current drive.
© 2025 Gauss Fusion GmbH - confidential
82
Ohmic current drive
But… resistivity decreases with temperature, while radiative losses increase.
Maximum temperature achievable ~3.3keV. Therefore we need additional
heating.
Also intrinsically a pulsed operation, therefore need additional current drive to
achieve steady-state.
© 2025 Gauss Fusion GmbH - confidential
83
Current drive
Instead of using the inductive effect of the transformer circuit, plasma current can
be driven by e.g.
Injected directed neutral beams
Injected travelling RF waves
In existing machines, the best current drive efficiencies allow up to 0.3A current to
be supported by 1W of power. This would be sufficient to support a power plant in
steady state, with approximately 30MA and 100MW.
This is expected to be harder in real power plants, but we need to confirm how
much harder (increasing T is beneficial; increasing n and R is not).
© 2025 Gauss Fusion GmbH - confidential
84
Current drive in JET
Plasma current maintained
with no applied voltage.
Litauden et al, “Towards fully non-inductive Current
Drive Operation in JET”, EFDA–JET–PR (01)65
© 2025 Gauss Fusion GmbH - confidential
85
INHERENTLY LONG PULSE
Stellarators are steady-state by nature
https://www.linkedin.com/posts/max-planck-institutefor-plasma-physics_fusionenergy-nuclearfusionscience-activity-6998650642382618627vIXI?utm_source=share&utm_medium=member_deskt
op
© 2025 Gauss Fusion GmbH - confidential
Figure 3. Time traces of the long pulse scenario with a total discharge length
of 480 s: ECR heating power and mean plasma density (top), diamagnetic
energy and toroidal bootstrap current (middle), and the divertor surface
temperature (bottom).
O. Grulke et al 2024 Nucl. Fusion 64 112002
86
Predicting future performance
Multi-machine database regression. Plus, increasingly, theory and simulation-based models.
© 2025 Gauss Fusion GmbH - confidential
87
STELLARATOR SCALING LAWS
GIGA does not require significant improvement in confinement
•
•
Physics of GIGA is within reach of existing databases 𝜏iss04 ≤ 1
Challenge is building coils
GIGA
GIGA
Adapted from A. Dinklage et al 2007
Nucl. Fusion 47 1265 (Fig 7)
© 2025 Gauss Fusion GmbH - confidential
Adapted from R. Wolf et al. 2019 Phys. Plasmas 26 082504 (Fig 14)
88
How do we build a thing like this?
What is Systems Engineering?
Process to develop something that’s too complex to build as a single entity
• Build the right system
• Build the system right
Why do Systems Engineering?
Sub-systems have individual & local idealities
• System optimisation
• Early incorporation structures Concept Phase approach
• Complexity & risk management beyond Concept Phase
•
Fundamentals of Systems Engineering
Stakeholder needs & objectives
• Systems & functionality decomposition
• Defining & controlling interfaces
• Defining various requirements
• Risk assessment
• Trade-offs & optimisation
• Technology Verification & Validation planning
•
© 2025 Gauss Fusion GmbH - confidential
89
MITIGATING PROJECT RISK
Choose the best available technologies, design around them
Make your unique project look as much like a previous one as possible
Make it as modular as possible
How Big Things Get Done – Bjorn Flyvbjerg
Downselection of materials and technologies:
•
HCPB-like blanket, 170 GHz gyrotrons, superconductors with a supply chain
•
Codified materials
•
Take safety and regulatory requirements into account from the start
•
Design in margin – the most optimised plant is the one that works
•
Steady-state is your friend, avoid cyclic loading
•
Economics dominated by availability
•
Larger components are harder to handle (logistics, assembly…)
© 2025 Gauss Fusion GmbH - confidential
90
TECHNOLOGY ASPECTS
Interdependent design requirements
© 2025 Gauss Fusion GmbH - confidential
91
SYSTEMS ENGINEERING AND INTEGRATED ANALYSIS
A stable, self-consistent design point for engineering confidence
© 2025 Gauss Fusion GmbH - confidential
92
OVERVIEW OF THE CONSTRUCTION AND ASSEMBLY PROCESS
Long manufacturing times require careful planning and prototyping
Procurement
© 2025 Gauss Fusion GmbH - confidential
Manufacturing
Prototype
93
STAGED COMMISSIONING
Leveraging the commissioning process for maximum data
© 2025 Gauss Fusion GmbH - confidential
94
GAUSS FUSION ROADMAP
Roadmap to build first FPP in Europe by 2040s
Phase 1 : Concept
Phase 2 : Engineering
2023-2025
2026-2032
Conceptual Design Report
Technical Design Report
Phase 3a : Construction
2031-2038
Pre CDR
Site selection
Phase 3a : Commissioning
2037-2044
Stage 1 H
Stage 2
D-T open
Operation
Stage 3
D-T closed
First Plasma First T bred First GWe
• Choice of Device: Stellarator
• Choice of TBM concept: HCPB
• Design of modular TBB
• Magnet system definition
• Design and test of demountable
coils
• Optimisation of the Stellarator
design for operation and
maintenance
© 2025 Gauss Fusion GmbH - confidential
• Blanket prototype
• VV prototype
• Magnet model coil
• Optimized ECRH system
• Integrated tritium fuel cycle test
• Procurement of long lead time
items
• Design remote maintenance
• Licensing process​
• Site preparation
• Licensing approval
• Major procurement activities
• Delivery of components
• Test and quality control
• Assembly and construction
• Test remote maintenance
• Start of staged commissioning
• Operational concept proven
• Control systems optimisation
• Start roll-out of fusion
fleet
95
ENABLING TECHNOLOGY DEVELOPMENT ON THE FIVE-YEAR HORIZON
Near-term milestones
HTS tape delivery!
Demountable cable joint
tested with LTS and
HTS conductors
2025
Validation of the demountable
coil test model
2026
Blanket modelling to
confirm concept
© 2025 Gauss Fusion GmbH - confidential
Manufacturing
demonstration of 3D
coil structural concept
2028
2027
½-size demountable
model coil tests
2029
Design for blanket
module complete
Assembly of module
structural prototype
Breeding blanket
module test
Design and Integration
of divertor with fuel
exhaust
Demonstration of
laser-based tritium
surface measurement
Demonstration of
Fuel Cycle Reactor
Interface
Images: Gauss Fusion, ENEA, ASI
96
Conclusions
A tokamak uses a combination of magnetic field coils and plasma currents to insulate the plasma, hold it in
equilibrium, and prevent gross instabilities.
Although there is always turbulence present in the plasma (as there is in flowing water), adequate insulation
is still achievable.
A combination of good insulation and high power heating allows high temperatures to be achieved.
A steady-state tokamak is feasible using external current drive methods as well as self-driven currents.
Stellarators are more complex from an engineering perspective, but inherently steady-state.
There are limits on plasma pressure due to confinement, equilibrium, and stability. A high fusion gain relies
on high pressure and high confinement time.
Steady progress made over last half-century but considerable engineering effort remains to achieve the goal.
We need to build on what ITER has started.
© 2025 Gauss Fusion GmbH - confidential
97
Questions?
© 2025 Gauss Fusion GmbH - confidential
98
Questionnaire
Thank you for your attention!
© 2025 Gauss Fusion GmbH - confidential
99