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Click image above for Torulf Greek's animation of the Boron-Proton (a.k.a. Boron-Hydrogen) fusion reaction.

Hydrogen-Boron vs. Deuterium-Tritium

Posted by Admin on Jul 16, 2006 at 11:17 PM
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Nuclear fusion has the potential to generate power without the radioactive waste of nuclear fission, but that depends on which atoms you decide to fuse.  Conventional fusion approaches work with deuterium and tritium (DT), while focus fusion works with hydrogen and boron eleven (pB11).

The Conventional Approach - Deuterium-Tritium Fuel

Most fusion research today is focused on fusing deuterium and tritium. Deuterium has one proton and one neutron. Tritium has one proton and two neutrons. When they come together there are two protons and three neutrons. This unstable configuration then splits into a helium atom (two protons and two neutrons) and a high energy neutron. These neutrons create heat and radioactive materials just as in a fission reactor.

Deuterium and helium are not radioactive and occur in nature. Tritium, however, is radioactive and does not occur in nature. It must be created in the reactor by using neutrons. So deuterium-tritium fusion still has two of the disadvantages of nuclear fission:

  * Some of the fuel (tritium) is radioactive. (Note, Tritium has other drawbacks as well: It is in short supply and it can be used in nuclear weapons.)
  * The high energy neutrons can take ordinary materials in the reactor building and make them radioactive.

Deuterium-tritium fusion would produce much less radioactive waste than fission, but radioactive waste can be avoided altogether by choosing a better fuel.

The Clean Alternative - Hydrogen Boron Fuel

Boron-11 is an atom that contains five protons and six neutrons.  Boron exists naturally as 19.9% 10B isotope and 80.1% 11B isotope.  Boron-11 can fuse with a hydrogen atom (one proton, no neutrons.) This makes six protons and six neutrons which is exactly enough for three helium atoms with no left over neutrons. The helium atoms then fly off at high speeds carrying the fusion energy. So hydrogen-boron fusion can create energy without releasing neutrons.

Boron-11 is a common element that exists in the earth’s crust and seawater. You may even have some in your house if you own a box of Borax. Hydrogen is the most common element in the universe and is even part of water as demonstrated by the formula H2O. Helium is the second most common element in the universe and is what makes children’s balloons and blimps float. None of these materials is radioactive.

Hydrogen-Boron process eliminates radioactive waste

So, when a boron-11 atom fuses with a hydrogen atom the result is three helium atoms and energy, but no radioactive waste:

  * The fuel (boron and hydrogen) is not radioactive.
  * The reaction product (helium) is not radioactive.
  * The reaction releases no neutrons.

It is true that the hydrogen-boron reaction releases no neutrons, but as fusion progresses a greater number of helium atoms are created and occasionally a boron atom will fuse with a helium instead of a hydrogen. This produces a (non-radioactive) nitrogen atom and a neutron. However, this reaction releases very little energy and so the neutron is not the same as the high energy neutrons produced by fission or deuterium-tritium fusion. These low-energy neutrons can create a small amount of short-lived radioactive materials, but these materials decay so quickly that it would be safe to enter a room containing a focus fusion device seconds after it is turned off.

Additionally, at such high temperatures electrons do emit x-rays. These are exactly the same as the x-rays produced in your doctor’s office, or in the baggage scanning machines at the airport. X-rays can be dangerous if people are exposed to large doses, but they can be stopped by lead shielding. Our society has extensive experience using x-rays safely. Together these low energy neutrons, x-rays, and short-lived radioactive materials disappear quickly and do not generate radioactive waste.

Hydrogen-Boron process generates electricity directly

As noted, a conventional fusion reactor using deuterium-tritium fuel is designed to produce neutrons that create heat. This heat energy would require expensive turbines and generators to form electricity. In contrast to this, A focus fusion reactor using hydrogen-boron fuel would produce electricity directly.

The energy from fusion reactions is released mainly in the form of a high energy helium nuclei. In focus fusion reactors, these nuclei come out in the form of a tight pulsed beam, in other hydrogen-boron reactor types, they would come out as a broader stream.

Since the nuclei are electrically charged, they already form an electric current. All that is needed is to capture this electric energy into an electric circuit. In focus fusion reactors, this can be done by allowing the pulsed beam to generate electric currents in a series of coils as it passes through them.

This is much the same way that a transformer works, stepping electric power down from the high voltage of a transmission line to the low voltage used in homes and factories. Such an electrical transformation can be highly efficient, probably around 80-90%.

What is most important is that it is exceedingly cheap and compact. The whole apparatus of steam turbine and electrical generator are eliminated. The energy from the x-rays can also be converted directly into electricity in a compact, cheap way. So hydrogen-boron fuel could potentially cut the cost of electric generation by a factor of 100.

The Challenge: B-11 requires higher ignition temperatures

So why, you may wonder, are researchers spending so much time on deuterium-tritium fusion when hydrogen-boron has clear advantages? The reason is that deuterium-tritium fusion is easier to ignite. It requires temperatures of only 100 million Kelvin while hydrogen-boron fusion requires 1 billion Kelvin.

Unfortunately, many fusion researchers have spent their careers developing a device called the tokamak which cannot reach the temperatures required for hydrogen-boron fusion.

Rather than looking for new ideas, the fusion research establishment has decided that the radioactive waste produced by deuterium-tritium fusion is acceptable.

However, there is a device which can reach 1 billion Kelvin - the Focus Fusion device.


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There are (8) comments.

I am wondering, after the hydrogen fuses with the boron 11 why does the resulting carbon 12 atom (which is stable) break into 3 helium atoms?

Rezwan's avatar

Hello Jaycub.  Perhaps this FAQ can explain it.  See especially the comments.

H.Nightroad's avatar

... i want to just say that if you catually bothered looking at everything you’d realize that the b-h fusion is so inefficient and has so many losses that it is not actually viable, the energy density for the b-h reaction is like 0.014 W/m3/kPa2 where as the energy density of the d-t fusion is like 34 W/m3/kPa2, this and the fact that the b-h fusion needs 10 times the temparture to achive a lesser amount of energy, and the fact that there is not too many actual ways to contain a fusion reaction that is at 1 billion degrees celcius… all of these facts point towards the fact that d-t fusion process is more effective and efficient than that of the b-h fusion process.

Rezwan's avatar

Hello Loki!  Thanks for the comments.  You’re right.  That’s not all!  On top of the higher temperature and density-confinement time product issue, the higher atomic charge of boron ions leads to the production of greater amounts of X-ray energy than DT - the emission of which cools the plasma, making plasma heating even more difficult.

These are serious technical challenges.  Lerner has some ideas about how to overcome them.  Some of us think that’s worth testing. 

If it fails, well, there’s always “effective and efficient” DT to fall back on.

If Boron 11 can’t be ignited when the device is completed this year (hopefully), has Helium 3 been considered for Focus Fusion as a backup. Helium 3 like Boron 11 would be aneutronic and has a much lower ignition temperature. Right now it is scarce but once we establish a base on the Moon we could mine it from the Luner soil. Later on, there is an abundance in the atmosphere of Saturn. This seems like a better “fall back” than DT.

Posted by DIGH on 6/17.

Plan C:
Use FF to generate neutrons and support a reaction in fission reactor which is burning nuclear waste.

In any case I am sure something good will come out of this.

Right! You’r talking about a fusion/fission hybrid. The neutrons would be absorbed by a blanket of thorium.
There are advantages with all thorium fission plants:

  Less radioactive waste
  The fuel is cheap and plentiful
  Most designs cannot go out of control
  Yes it can burn up high level radioactive waste

The molten salt reactor design was one of the most promising and a working prototype was running in the early seventies. Then they pulled the plug and shut it down. The design was never revived. Lets hope FF doesn’t meet the same fate.

Brian H's avatar

Observe the dangers of depending on government funding and bureaucratic decision-making.

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