Tungsten 'too brittle' for nuclear fusion reactors

April 11, 2018, University of Huddersfield
Credit: University of Huddersfield

Scientists at the University of Huddersfield have been using world-class new facilities to carry out experiments that could aid the development of nuclear fusion reactors, widely regarded as the "Holy Grail" solution to future energy needs.

By simulating the damage caused by high energy neutrons and produced during the process, the Huddersfield researchers have discovered that – a favoured choice of metal within the reactor – is liable to become brittle, leading to failure.

"At this moment in time, even though tungsten is a leading candidate, we don't see how we can use it as a structural material. We can use it as a barrier, but not for anything structurally sound," states Dr. Robert Harrison, who is a Research Fellow at the University of Huddersfield's Electron Microscopy and Materials Analysis Research Group (EMMA).

The answer will be to develop a new alloy that combines tungsten – which has desirable properties of extreme hardness and exceptionally high melting temperature – with some other material that can prevent its embrittlement from radiation damage and nuclear transmutation reactions, which would have significant safety implications for the operation of the reactor.

Dr. Harrison and his colleagues have access to the University of Huddersfield's Microscope and Ion Accelerator for Materials Investigation (MIAMI) facilities. These combine ion irradiation with transmission . Newly-opened MIAMI-2 – developed with an award of £3.5 million from the Engineering and Physical Sciences Research Council – has dual ion beams and is one of the world's leading facilities of its kind.

Dr Robert Harrison. Credit: University of Huddersfield

By using both helium and tungsten ions to safely replicate the alpha particles created during a fusion reaction and the neutron bombardment, the EMMA researchers have been able to replicate the damage caused to tungsten. The findings are described in a new article in the journal Scripta Materialia, authored by Dr. Harrison with Dr. Jonathan Hinks and Professor Stephen Donnelly.

Progress is being made towards the development of , which fuses atoms rather than splits them as in a conventional fission reactor. Under construction in France is the International Experimental Fusion Reactor, which aims to be the first that produces more energy than it consumes.

At the Culham Centre for Fusion Energy in Oxfordshire, the Joint European Torus (JET), is the world's largest operational magnetic confinement plasma physics experiment, intended to open the way to future nuclear fusion grid energy.

Advocates for nuclear fusion state that it has the potential to generate almost limitless, clean that is "too cheap to meter." Research such as the University of Huddersfield investigation of tungsten could help bring the breakthrough closer.

Explore further: Metal cloud to protect fusion reactor walls

More information: R.W. Harrison et al. Influence of pre-implanted helium on dislocation loop type in tungsten under self-ion irradiation, Scripta Materialia (2018). DOI: 10.1016/j.scriptamat.2018.02.040

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21 comments

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EyeNStein
2.5 / 5 (2) Apr 11, 2018
Hydrogen/Deuterium also causes Tungsten to blister and flake off in the long term.
Lithium coated tungsten might do better for a steady state reactor.
ITER and JET use tungsten as they are long pulsed mode test reactors and poisoning the plasma is their biggest concern.
barakn
1.7 / 5 (3) Apr 11, 2018
Why would you coat the tungsten with lithium? The whole point is to have exposed surfaces covered with a material that has a high melting point and doesn't ionize easily.
Paulw789
3 / 5 (2) Apr 11, 2018
No material is going to hold up against the neutron radiation produced in D-T fusion.

All the money being spent on D-T fusion is wasted since they have no way to control the extreme high energy neutron radiation.

Fusion will have to be done with other elements and other isotopes that does not produce this kind of radiation.
mackita
1.8 / 5 (5) Apr 11, 2018
This is suspiciously too much effort before admitting the reality of cold fusion. The hot fusion researchers know quite well, that once cold fusion will get widespread, the subsidizations of their research will end. At least we know, that the ITER (which is also made of tungsten) will not be capable of prolonged run.
ekim
2.3 / 5 (3) Apr 11, 2018
No material is going to hold up against the neutron radiation produced in D-T fusion.

All the money being spent on D-T fusion is wasted since they have no way to control the extreme high energy neutron radiation.

Fusion will have to be done with other elements and other isotopes that does not produce this kind of radiation.

Or, they could surround the reaction in a liquid lead and lithium shell. The lead absorbs any radiation while the lithium absorbs the neutrons leading to a secondary fusion reaction producing more power and tritium, a valuable fuel in fusion reactors. This is the approach of General Fusion, a company out of Canada.
antialias_physorg
4.2 / 5 (5) Apr 11, 2018

All the money being spent on D-T fusion is wasted since they have no way to control the extreme high energy neutron radiation.

You know how we control the neutron radiation in fission reactors? Ever seen these big concrete shells they build around these powerplants? There ya go - that's what they are there for.
EyeNStein
not rated yet Apr 11, 2018
The Neutron cross section of Tungsten is low and the extreme energy neutrons zip through it, But the plasma instabilities force D/T ions into the surface which embrittles and blisters the tungsten.
A FLiBe molten salt jacket around the reactor safely absorbs the neutrons huge energy which is why the ARC reactor design uses it.
The Lithiums' job is to react with stray edge plasma D/T and hold it for later reuse; as PPPL have proven.
cantdrive85
1 / 5 (1) Apr 11, 2018
How to vaporize a tungsten tipped Langmuir probe.
https://vimeo.com/255206366
ursiny33
5 / 5 (1) Apr 11, 2018
Its a waste of time , when mechanical motion can be produced by stationary and revolving like permanent field assemblies producing magnetic repulsion field forces which can be controlled by timed high voltage field envelopment contained in flat capacitors over the revolving field assemblies that are charged by induction circuitry from the motion and discharged to ground in timed mechanical sequences.
Thorium Boy
3 / 5 (2) Apr 11, 2018
They need a ceramic, not a metal.
Osiris1
not rated yet Apr 12, 2018
Use a different metal. Tungsten oxydizes and poisons plasma used in fusion.
mackita
not rated yet Apr 13, 2018
Ceramic is brittle as well, plasma fusion runs in vacuum, thus no oxidization...
gkam
1 / 5 (4) Apr 13, 2018
This is irrelevant. We do not need it.
TheGhostofOtto1923
5 / 5 (3) Apr 13, 2018
No material is going to hold up against the neutron radiation produced in D-T fusion
Typical smelly pessimist
This is irrelevant. We do not need it
Typical smelly psychopath.
Thorium Boy
not rated yet Apr 18, 2018
Many years ago, when they were considering Project Orion, the nuclear-bomb powered spacecraft, they wanted to find a way to keep the nuclear blasts from ablating the iron shell reflector that contained them. They found out that a repletishable oil layer was sufficient to protect the steel from ablation. I'm not clear on the mechanism, but that's something they could try.
granville583762
1 / 5 (1) Apr 19, 2018
Conservation of energy
Its all academic which material is used, the temperature is a 100million degrees - the energy of fusion is the energy needed to heat and compress hydrogen to the point of fusion.
Conservation of energy states you cannot get more out than you put in!
antialias_physorg
5 / 5 (1) Apr 19, 2018
Conservation of energy states you cannot get more out than you put in!

That's why applying a match to burn a pile of wood doesn't work, right?
EyeNStein
not rated yet Apr 19, 2018
Like I said Tungsten goes brittle:-..
https://www.pppl....rinceton
But its good for temporary test reactors as it doesn't easily vaporise and poison the plasma.
Beryllium is better but that poisons the physicists.

Lithium coating captures edge plasma D/T and even helps stabilise the H mode plasmas as it evaporates:-
https://www.pppl....ment-ltx

And for the ignorant who bash ITER as a project and want ARC built tomorrow, this is MIT's view:- https://www.youtu...uAx1COEk
( MIT's SPARC is likely to be actually built as its experimentally useful to advance fusion knowledge; and gives us our improving fusion triple product 'Moore's law' back. )

We also need to capture the neutrons in some Lithium or we cant breed our Tritium fuel.
granville583762
1 / 5 (1) Apr 19, 2018
By implication antialias_physorg you are saying nature has a method of using less energy to get hydrogen to the point of fusion than fusion releases when hydrogen fuses, you have just solved where all the mass and energy has come from!
antialias_physorg> Conservation of energy states you cannot get more out than you put in!

That's why applying a match to burn a pile of wood doesn't work, right?

granville583762
1 / 5 (1) Apr 20, 2018
The uncomfortable truth - fusion- reactors work but don't work. Other wise it is an over unity machine!
The energy to fuse hydrogen to helium is the energy of fusion that is released upon fusion!
By implication antialias_physorg you are saying nature has a method of using less energy to get hydrogen to the point of fusion than fusion releases when hydrogen fuses, you have just solved where all the mass and energy has come from!
antialias_physorg> Conservation of energy states you cannot get more out than you put in!

That's why applying a match to burn a pile of wood doesn't work, right?


holoman
not rated yet May 10, 2018
https://drive.goo...bTCKVo4G

Hydra Fusion Reactor

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